Journal articles: 'Tokamak'

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El-zmeter, Nour El-Houda, Benjamin Schmiga, Brendan Boyd-Weetman, and Alicia Murphy. "Analysis of Tokamak fusion device parameters affecting the efficiency of Tokamak operation." PAM Review Energy Science & Technology 4 (June 5, 2017): 87–102. http://dx.doi.org/10.5130/pamr.v4i0.1444.

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Nuclear Power has been available as a relatively clean and reliable energy source for several decades. While tokamak engines have been in existence almost as long as successful fission-powered nuclear generators, they have not yet reached operational success for energy generation. This meta study collates key fusion device parameters and determines ideas on the applicability of fusion devices for energy. This paper supports the argument that toroidal tokamaks are not limited by volume whereas spherical designs have a potential volume limit, spherical tokamaks use a lower magnetic field current than toroidal tokamaks. Further scientific and engineering progress is required before tokamak devices can be a viable technology to be used for energy generation.

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Whyte, Dennis. "Small, modular and economically attractive fusion enabled by high temperature superconductors." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2141 (February 4, 2019): 20180354. http://dx.doi.org/10.1098/rsta.2018.0354.

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The advantages of high magnetic fields in tokamaks are reviewed, and why they are important in leading to more compact tokamaks. A brief explanation is given of what limits the magnetic field in a tokamak, and why high temperature superconductors (HTSs) are a game changer, not just because of their higher magnetic fields but also for reasons of higher current density and higher operating temperatures. An accelerated pathway to fusion energy is described, defined by the SPARC and ARC tokamak designs. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

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Windridge, Melanie. "Smaller and quicker with spherical tokamaks and high-temperature superconductors." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2141 (February 4, 2019): 20170438. http://dx.doi.org/10.1098/rsta.2017.0438.

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Research in the 1970s and 1980s by Sykes, Peng, Jassby and others showed the theoretical advantage of the spherical tokamak (ST) shape. Experiments on START and MAST at Culham throughout the 1990s and 2000s, alongside other international STs like NSTX at the Princeton Plasma Physics Laboratory, confirmed their increased efficiency (namely operation at higher beta) and tested the plasma physics in new regimes. However, while interesting devices for study, the perceived technological difficulties due to the compact shape initially prevented STs being seriously considered as viable power plants. Then, in the 2010s, high-temperature superconductor (HTS) materials became available as a reliable engineering material, fabricated into long tapes suitable for winding into magnets. Realizing the advantages of this material and its possibilities for fusion, Tokamak Energy proposed a new ST path to fusion power and began working on demonstrating the viability of HTS for fusion magnets. The company is now operating a compact tokamak with copper magnets, R 0 ∼ 0.4 m, R / a ∼ 1.8, and target I p = 2MA, B t0 = 3 T, while in parallel developing a 5 T HTS demonstrator tokamak magnet. Here we discuss why HTS can be a game-changer for tokamak fusion. We outline Tokamak Energy's solution for a faster way to fusion and discuss plans and progress, including benefits of smaller devices on the development path and advantages of modularity in power plants. We will indicate some of the key research areas in compact tokamaks and introduce the physics considerations behind the ST approach, to be further developed in the subsequent paper by Alan Costley. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

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Pankratov, Igor M., and Volodymyr Y. Bochko. "Nonlinear Cone Model for Investigation of Runaway Electron Synchrotron Radiation Spot Shape." 3, no. 3 (September 28, 2021): 18–24. http://dx.doi.org/10.26565/2312-4334-2021-3-02.

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The runaway electron event is the fundamental physical phenomenon and tokamak is the most advanced conception of the plasma magnetic confinement. The energy of disruption generated runaway electrons can reach as high as tens of mega-electron-volt and they can cause a catastrophic damage of plasma-facing-component surfaces in large tokamaks and International Thermonuclear Experimental Reactor (ITER). Due to its importance, this phenomenon is being actively studied both theoretically and experimentally in leading thermonuclear fusion centers. Thus, effective monitoring of the runaway electrons is an important task. The synchrotron radiation diagnostic allows direct observation of such runaway electrons and an analysis of their parameters and promotes the safety operation of present-day large tokamaks and future ITER. In 1990 such diagnostic had demonstrated its effectiveness on the TEXTOR (Tokamak Experiment for Technology Oriented Research, Germany) tokamak for investigation of runaway electrons beam size, position, number, and maximum energy. Now this diagnostic is installed practically on all the present-day’s tokamaks. The parameter v┴/|v||| strongly influences on the runaway electron synchrotron radiation behavior (v|| is the longitudinal velocity, v┴ is the transverse velocity with respect to the magnetic field B). The paper is devoted to the theoretical investigation of runaway electron synchrotron radiation spot shape when this parameter is not small that corresponds to present-day tokamak experiments. The features of the relativistic electron motion in a tokamak are taken into account. The influence of the detector position on runaway electron synchrotron radiation data is discussed. Analysis carried out in the frame of the nonlinear cone model. In this model, the ultrarelativistic electrons emit radiation in the direction of their velocity v→ and the velocity vector runs along the surface of a cone whose axis is parallel to the magnetic field B. The case of the small parameter v┴/|v||| (v┴/|v|||<<1, linear cone model) was considered in the paper: Plasma Phys. Rep. 22, 535 (1996) and these theoretical results are used for experimental data analysis.

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Manheimer, Wallace. "Comment on ‘The advanced tokamak path to a compact net electric fusion pilot plant’." Nuclear Fusion 62, no. 12 (October 18, 2022): 128001. http://dx.doi.org/10.1088/1741-4326/ac88e4.

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Abstract This comment (letter) examines a recent GA concept which they hope will lead to a tokamak fusion pilot plant. As tokamaks are now the closest configuration to practical magnetic fusion, if they cannot do a pilot plant, almost certainly no other device can either. The conclusion is that constructing a tokamak fusion pilot plant at this time is enormously risky, and is almost certainly tremendous waste of scarce fusion resources, which could be better used on other efforts in the fusion effort.

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Hirsch, Robert L., and Roger H. Bezdek. "Public Acceptance of ITER-Tokamak Fusion Power." European Journal of Energy Research 1, no. 4 (October 8, 2021): 8–12. http://dx.doi.org/10.24018/ejenergy.2021.1.4.18.

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One of the U.S. Electric Power Research Institute’s criteria for practical fusion power is public acceptance. In this analysis we consider the potential public acceptance of ITER-tokamak fusion power. Because ITER-like reactors are not likely to be commercially ready before mid-century, a forecast of public acceptance is very difficult. We break “the public” down into four entities: 1) Rank and file consumers, 2) Governments [local, state, & federal including regulators], 3) NGOs including environmental groups, and 4) Electric utilities. We assert that ITER-tokamaks will be evaluated in the context of fission power because both are nuclear processes. We observe that ITER-tokamak fusion will present radioactive hazards and be extremely expensive. Three possible futures for fission nuclear mid-century are: 1) full acceptance, 2) middling acceptance, and 3) rejection. If fission power is accepted mid-century, then ITER-tokamak fusion stands the best chance of being publicly acceptable, its largest drawback being very high cost. If fission power is of middling acceptance, then ITER-tokamak fusion might be marginally more acceptable because of its much shorter life radioactive waste. If fission power is unacceptable, then ITER-tokamak fusion acceptance will be very difficult.

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KROETZ, T., CAROLINE G. L. MARTINS, M. ROBERTO, and I. L. CALDAS. "Set of wires to simulate tokamaks with poloidal divertor." Journal of Plasma Physics 79, no. 5 (April 12, 2013): 751–57. http://dx.doi.org/10.1017/s0022377813000391.

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AbstractSimple wire models have been proposed to simulate magnetic configurations in tokamaks. Here we consider electric currents in five parallel infinite wires to obtain double-null magnetic surfaces with specific choices of magnetic axis positions, triangularity, and elongation. As an example, we choose the position and the electric current of each wire to obtain magnetic surfaces similar to those expected in the tokamak international thermonuclear experimental reactor. Moreover, we also integrate the perturbed field line differential equation to simulate chaotic layers near the hyperbolic points and deposition patterns at the divertor plate observed in tokamaks. To simulate that, we add to the model a perturbing error field, due to asymmetries in the tokamak coils, and introduce a random collisional term to the field line mapping to reproduce escape pattern alterations due to particle collisions.

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Podpaly, Y. A., J. E. Rice, P. Beiersdorfer, M. L. Reinke, J. Clementson, and H. S. Barnard. "Tungsten measurement on Alcator C-Mod and EBIT for future fusion reactors1This article is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas." Canadian Journal of Physics 89, no. 5 (May 2011): 591–97. http://dx.doi.org/10.1139/p11-038.

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Tungsten will be an important element in nearly all future fusion reactors because of its presence in plasma facing components. This makes tungsten a good candidate for a diagnostic element for ion temperature and toroidal velocity measurement, and it makes understanding tungsten emissions important for tokamak power balance. The effect of tungsten on tokamak plasmas is investigated at the Alcator C-Mod tokamak using VUV, bolometry, and soft X-ray spectroscopy. Tungsten was present in Alcator C-Mod as a plasma facing component and through laser blow-off impurity injection. Quasi-continuum emission previously seen at other tokamaks has been identified. Theoretical predictions are presented of tungsten emission that could be expected in future Alcator C-Mod measurements. Furthermore, spectra of highly charged tungsten ions have been studied at the SuperEBIT electron beam ion trap. This emission could prove useful for spectroscopic diagnostics of future high-temperature fusion reactor plasmas.

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Garrido, Izaskun, Aitor J. Garrido, Jesús A. Romero, Edorta Carrascal, Goretti Sevillano-Berasategui, and Oscar Barambones. "Low EffortLiNuclear Fusion Plasma Control Using Model Predictive Control Laws." Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/527420.

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One of the main problems of fusion energy is to achieve longer pulse duration by avoiding the premature reaction decay due to plasma instabilities. The control of the plasma inductance arises as an essential tool for the successful operation of tokamak fusion reactors in order to overcome stability issues as well as the new challenges specific to advanced scenarios operation. In this sense, given that advanced tokamaks will suffer from limited power available from noninductive current drive actuators, the transformer primary coil could assist in reducing the power requirements of the noninductive current drive sources needed for current profile control. Therefore, tokamak operation may benefit from advanced control laws beyond the traditionally used PID schemes by reducing instabilities while guaranteeing the tokamak integrity. In this paper, a novel model predictive control (MPC) scheme has been developed and successfully employed to optimize both current and internal inductance of the plasma, which influences the L-H transition timing, the density peaking, and pedestal pressure. Results show that the internal inductance and current profiles can be adequately controlled while maintaining the minimal control action required in tokamak operation.

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Stepanenko, A. A. "Effect of electromagnetic wave reflection from conducting surfaces on blob dynamics in the tokamak scrape-off layer." Physics of Plasmas 30, no. 4 (April 2023): 042301. http://dx.doi.org/10.1063/5.0140097.

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Electromagnetic dynamics of blobs in hot scrape-off-layer plasmas of the tokamak are affected by excitation of the Alfvén waves and their subsequent propagation to the machine first wall along open magnetic field lines. In this study, the interaction of electromagnetic perturbations with the conducting tokamak wall and the resulting impact of these perturbations on the motion of filaments at the tokamak edge are analyzed. The model describing blob dynamics is presented. To describe the reflection of the Alfvén waves from the tokamak wall, the new form of sheath boundary conditions for the parallel current and electrostatic potential at the plasma–sheath interface is proposed. It is demonstrated that depending on the wall resistivity, the waves can be either absorbed or reflected by the wall, influencing the excitation of electromagnetic fluctuations inside the filament plasma. The theoretical conclusions of the study are supported with the BOUT++ numerical modeling of blob dynamics at the edge of the DIII-D and NSTX tokamaks. It is shown that taking the reflective boundary conditions into account leads to the excitation of the standing Alfvén waves in the filament, periodically canceling the electrostatic currents inside the blob.

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Voronin A.V., Goryainov V. Yu., Zabrodsky V. V., Sherstnev E. V., Kornev V. A., Aruev P. N., Kurskiev G. S., Zhubr N. A., and Tukachinsky A. S. "Plasma electron temperature measurement by foil soft-X-Ray spectrometer installed on TUMAN-3M and Globus-M2 tokamaks." Technical Physics 67, no. 15 (2022): 2377. http://dx.doi.org/10.21883/tp.2022.15.55263.188-21.

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Technical solution were presented for a foil spectrometer installed on the Globus-M2 and TUMAN-3M tokamaks for measuring the electron plasma temperature. Measurements have been carried out of the time dependence of the plasma temperature in the central region of tokamaks. Using of integrated photodetectors and unique beryllium foils with a thickness of 14-80 μm made it possible to increase the sensitivity of the spectrometer. An important quality of the foils used were the increased values of strength, plasticity, homogeneity, and the absence of surface and internal defects. The combined use of the spectrometer with Thomson scattering diagnostics made it possible to carry out regular temperature measurements in the Globus-M2 tokamak with a high spatial and temporal resolution. The influence of impurities is estimated on the measurement of the electron temperature of the plasma. Keywords: foil spectrometry, tokamak, plasma, continuum, bremsstrahlung, electron temperature, soft-X-Ray, Si-photodiode.

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Punjabi, Alkesh, Arun Verma, and Allen Boozer. "Tokamak divertor maps." Journal of Plasma Physics 52, no. 1 (August 1994): 91–111. http://dx.doi.org/10.1017/s0022377800017797.

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A mapping method is developed to investigate the problem of determination and control of heat-deposition patterns on the plates of a tokamak divertor. The deposition pattern is largely determined by the magnetic field lines, which are mathematically equivalent to the trajectories of a single-degree-of-freedom time-dependent Hamiltonian system. Maps are natural tools to study the generic features of such systems. The general theory of maps is presented, and methods for incorporating various features of the magnetic field and particle motion in divertor tokamaks are given. Features of the magnetic field include the profile of the rotational transform, single- versus double-null divertor, reverse map, the effects of naturally occurring low M and N, and externally imposed high-M, high-N perturbations. Particle motion includes radial diffusion, pitch angle and energy scattering, and the electric sheath at the plate. The method is illustrated by calculating the stochastic broadening in a single- null divertor tokamak. Maps provide an efficient, economic and elegant method to study the problem of motion of plasma particles in the stochastic scrape-off layer.

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Sadakov, Sergey, Fabio Villone, Daniel Iglesias, Luis Maqueda, Jesus Almenara-Rescalvo, Guglielmo Rubinacci, and Salvatore Ventre. "Practical Model for the Calculation of Lateral Electromagnetic Loads in Tokamaks at Asymmetric Vertical Displacement Events (AVDEs)." Plasma 7, no. 1 (March 13, 2024): 178–200. http://dx.doi.org/10.3390/plasma7010012.

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This paper describes a new practical numerical model for the calculation of lateral electromagnetic (EM) loads in tokamaks during asymmetric vertical displacement events (AVDEs). The model combines key features of two recently reported trial models while avoiding their drawbacks. Their common basic feature is the superposition of two patterns of halo current: one perfectly symmetric and another perfectly anti-symmetric. This model combines the following features that have not been combined before (a) a helically distorted halo layer wrapping around core plasma, and (b) halo-to-wall interception belts slipping along plasma-facing walls. This combination almost doubles the lateral net forces. An AVDE creates significant lateral net moments. Being relatively modest at VDEs, the lateral moments become a dominant component of EM loads at AVDEs. The model carefully tracks the balance of net EM loads (zero total for the tokamak), as a necessary condition for the consequent numerical simulation of the tokamak’s dynamic response. This balance is needed as well for the development of tokamak monitoring algorithms and simulators. In order to decouple from the current uncertainties in the interpretation and simulation of AVDE physics, the model does not simulate AVDE evolution but uses it as an input assumption based on the existing interpretation and simulation of AVDE physics. This means the model is to be used in a manner of parametric study, at widely varied input assumptions on AVDE evolution and severity. Parametric results will fill a library of ready-for-use waveforms of asymmetric EM loads (distributed and total) at tokamak structures and coils, so that the physics community may point to specific variants for subsequent engineering analysis. This article presents the first practical contribution to this AVDE library.

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Menard, J. E., B. A. Grierson, T. Brown, C. Rana, Y. Zhai, F. M. Poli, R. Maingi, W. Guttenfelder, and P. B. Snyder. "Fusion pilot plant performance and the role of a sustained high power density tokamak." Nuclear Fusion 62, no. 3 (February 7, 2022): 036026. http://dx.doi.org/10.1088/1741-4326/ac49aa.

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Abstract Recent U.S. fusion development strategy reports all recommend that the U.S. should pursue innovative science and technology to enable construction of a fusion pilot plant (FPP) that produces net electricity from fusion at low capital cost. Compact tokamaks have been proposed as a means of potentially reducing the capital cost of a FPP. However, compact steady-state tokamak FPPs face the challenge of integrating a high fraction of self-driven current with high core confinement, plasma pressure, and high divertor parallel heat flux. This integration is sufficiently challenging that a dedicated sustained-high-power-density (SHPD) tokamak facility is proposed by the U.S. community as the optimal way to close this integration gap. Performance projections for the steady-state tokamak FPP regime are presented and a preliminary SHPD device with substantial flexibility in lower aspect ratio (A = 2–2.5), shaping, and divertor configuration to narrow gaps to an FPP is described.

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Garrido, I., A. J. Garrido, M. G. Sevillano, and J. A. Romero. "Robust Sliding Mode Control for Tokamaks." Mathematical Problems in Engineering 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/341405.

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Nuclear fusion has arisen as an alternative energy to avoid carbon dioxide emissions, being the tokamak a promising nuclear fusion reactor that uses a magnetic field to confine plasma in the shape of a torus. However, different kinds of magnetohydrodynamic instabilities may affect tokamak plasma equilibrium, causing severe reduction of particle confinement and leading to plasma disruptions. In this sense, numerous efforts and resources have been devoted to seeking solutions for the different plasma control problems so as to avoid energy confinement time decrements in these devices. In particular, since the growth rate of the vertical instability increases with the internal inductance, lowering the internal inductance is a fundamental issue to address for the elongated plasmas employed within the advanced tokamaks currently under development. In this sense, this paper introduces a lumped parameter numerical model of the tokamak in order to design a novel robust sliding mode controller for the internal inductance using the transformer primary coil as actuator.

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Saperstein, A. R., J. P. Levesque, M. E. Mauel, and G. A. Navratil. "Halo current rotation scaling in post-disruption plasmas." Nuclear Fusion 62, no. 2 (January 6, 2022): 026044. http://dx.doi.org/10.1088/1741-4326/ac4186.

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Abstract Halo current (HC) rotation during disruptions can be potentially dangerous if resonant with the structures surrounding a tokamak plasma. We propose a drift-frequency-based scaling law for the rotation frequency of the asymmetric component of the HC as a function of toroidal field strength and plasma minor radius (f rot ∝ 1/B T a 2). This scaling law is consistent with results reported for many tokamaks and is motivated by the faster HC rotation observed in the HBT-EP tokamak. Projection of the rotation frequency to ITER and SPARC parameters suggest the asymmetric HC rotation will be on the order of 10 Hz and 60 Hz, respectively.

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Federici, Fabio, Matthew L. Reinke, Bruce Lipschultz, Andrew J. Thornton, James R. Harrison, Jack J. Lovell, and Matthias Bernert. "Design and implementation of a prototype infrared video bolometer (IRVB) in MAST Upgrade." Review of Scientific Instruments 94, no. 3 (March 1, 2023): 033502. http://dx.doi.org/10.1063/5.0128768.

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A prototype infrared video bolometer (IRVB) was successfully deployed in the Mega Ampere Spherical Tokamak Upgrade (MAST Upgrade or MAST-U), the first deployment of such a diagnostic in a spherical tokamak. The IRVB was designed to study the radiation around the lower x-point, another first in tokamaks, and has the potential to estimate emissivity profiles with spatial resolution beyond what is achievable with resistive bolometry. The system was fully characterized prior to installation on MAST-U, and the results are summarized here. After installation, it was verified that the actual measurement geometry in the tokamak qualitatively matches the design; this is a particularly difficult process for bolometers and was done using specific features of the plasma itself. The installed IRVB measurements are consistent both with observations from other diagnostics, including magnetic reconstruction, visible light cameras, and resistive bolometry, as well as with the IRVB-designed view. Early results show that with conventional divertor geometry and only intrinsic impurities (for example, C and He), the progression of radiative detachment follows a similar path to that observed for large aspect ratio tokamaks: The peak of the radiation moves along the separatrix from the targets to the x-point and high-field side midplane with a toroidally symmetric structure that can eventually lead to strong effects on the core plasma inside the separatrix.

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Sadakov, Sergey, Fabio Villone, Guglielmo Rubinacci, and Salvatore Ventre. "Simple Parametric Model for Calculation of Lateral Electromagnetic Loads in Tokamaks at Asymmetric Vertical Displacement Events (AVDE)." Plasma 5, no. 3 (July 25, 2022): 306–23. http://dx.doi.org/10.3390/plasma5030024.

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This paper describes a family of relatively simple numerical models for calculation of asymmetric electromagnetic (EM) loads at all tokamak structures and coils at asymmetric vertical plasma displacement events (AVDE). Unlike currently known AVDE studies concentrated on plasma physics, these models have a practical purpose to calculate detailed time-dependent patterns of AVDE-induced EM loads everywhere in the tokamak. They are built to intrinsically assure good-enough EM load balance (opposite net forces and torques for the Vacuum Vessel and the Magnets with zero total for the entire tokamak), as needed for consequent simulation of the tokamak’s dynamic response to AVDE, as well as for the development of tokamak monitoring algorithms and tokamak simulators. To achieve these practical goals, the models work in a manner of parametric study. They do not intervene in details of plasma physics, but run at widely varied input assumptions on AVDE evolution and severity. Their outputs will fill a library of ready-for-use lateral EM loads for multiple variants of AVDE evolution and severity. The tokamak physics community can select any variant from the library, and engineers can pick ready-for-use AVDE loads. Investigated here, EM models represent one already known approach and one newly suggested. The latter attempts to reflect the helical pattern of halo currents in plasma and delivers richer outcomes and, thus, can be preferred as the single practical model for parametric calculations.

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Liang, Chen, Zhuang Ma, Zhen Sun, Xiaoman Zhang, Xin You, Zhuang Liu, Guizhong Zuo, Jiansheng Hu, and Yan Feng. "Demonstration of object location, classification, and characterization by developed deep learning dust ablation trail analysis code package using plasma jets." Review of Scientific Instruments 94, no. 2 (February 1, 2023): 023506. http://dx.doi.org/10.1063/5.0123614.

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Based on deep learning, a Dust Ablation Trail Analysis (DATA) code package is developed to detect dust ablation trails in tokamaks, which is intended to analyze a large amount data of tokamak dusts. To validate and benchmark the DATA code package, 2440 plasma jet images are exploited for the training and test of the deep learning DATA code package, since plasma jets resemble the shape and size of dust ablation clouds in tokamaks. After being trained by 1920 plasma jet images, the DATA code package is able to locate 100% plasma jets, classify plasma jets with the accuracy of >99.9%, and output image skeleton information for classified plasma jets. The DATA code package trained by the plasma jet images is also used to analyze the dust ablation trails captured in the Experimental Advanced Superconducting (EAST) tokamak with the satisfactory performance, further verifying its applicability in the fusion dust ablation investigation. Based on its excellent performance presented here, it is demonstrated that our DATA code package is able to automatically identify and analyze dust ablation trails in tokamaks, which can be used for further detailed investigations, such as the three-dimensional reconstruction of dusts and their ablation trails.

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Cerovsky, J., O. Ficker, V. Svoboda, E. Macusova, J. Mlynar, J. Caloud, V. Weinzettl, and M. Hron. "Progress in HXR diagnostics at GOLEM and COMPASS tokamaks." Journal of Instrumentation 17, no. 01 (January 1, 2022): C01033. http://dx.doi.org/10.1088/1748-0221/17/01/c01033.

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Abstract Scintillation detectors are widely used for hard X-ray spectroscopy and allow us to investigate the dynamics of runaway electrons in tokamaks. This diagnostic tool proved to be able to provide information about the energy or the number of runaway electrons. Presently it has been used for runaway studies at the GOLEM and the COMPASS tokamaks. The set of scintillation detectors used at both tokamaks was significantly extended and improved. Besides NaI(Tl) (2 × 2 inch) scintillation detectors, YAP(Ce) and CeBr3 were employed. The data acquisition system was accordingly improved and the data from scintillation detectors is collected with appropriate sampling rate (≈300 MHz) and sufficient bandwidth (≈100 MHz) to allow a pulse analysis. Up to five detectors can currently simultaneously monitor hard X-ray radiation at the GOLEM. The same scintillation detectors were also installed during the runaway electron campaign at the COMPASS tokamak. The aim of this contribution is to report progress in diagnostics of HXR radiation induced by runaway electrons at the GOLEM and the COMPASS tokamaks. The data collected during the 12th runaway electron campaign (2020) at COMPASS shows that count rates during typical low-density runaway electron discharges are in a range of hundreds of kHz and detected photon energies go up to 10 MeV (measured outside the tokamak hall). Acquired data from experimental campaigns from both machines will be discussed.

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Dlougach, Eugenia, Alexander Panasenkov, Boris Kuteev, and Arkady Serikov. "Neutral Beam Coupling with Plasma in a Compact Fusion Neutron Source." Applied Sciences 12, no. 17 (August 23, 2022): 8404. http://dx.doi.org/10.3390/app12178404.

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FNS-ST is a fusion neutron source project based on a spherical tokamak (R/a = 0.5 m/0.3 m) with a steady-state neutron generation of ~1018 n/s. Neutral beam injection (NBI) is supposed to maintain steady-state operation, non-inductive current drive and neutron production in FNS-ST plasma. In a low aspect ratio device, the toroidal magnetic field shape is not optimal for fast ions confinement in plasma, and the toroidal effects are more pronounced compared to the conventional tokamak design (with R/a > 2.5). The neutral beam production and the tokamak plasma response to NBI were efficiently modeled by a specialized beam-plasma software package BTR-BTOR, which allowed fast optimization of the neutral beam transport and evolution within the injector unit, as well as the parametric study of NBI induced effects in plasma. The “Lite neutral beam model” (LNB) implements a statistical beam description in 6-dimensional phase space (106–1010 particles), and the beam particle conversions are organized as a data flow pipeline. This parametric study of FNS-ST tokamak is focused on the beam-plasma coupling issue. The main result of the study is a method to achieve steady-state current drive and fusion controllability in beam-driven toroidal plasmas. LNB methods can be also applied to NBI design for conventional tokamaks.

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Menard, J. E. "Compact steady-state tokamak performance dependence on magnet and core physics limits." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2141 (February 4, 2019): 20170440. http://dx.doi.org/10.1098/rsta.2017.0440.

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Compact tokamak fusion reactors using advanced high-temperature superconducting magnets for the toroidal field coils have received considerable recent attention due to the promise of more compact devices and more economical fusion energy development. Facilities with combined fusion nuclear science and Pilot Plant missions to provide both the nuclear environment needed to develop fusion materials and components while also potentially achieving sufficient fusion performance to generate modest net electrical power are considered. The performance of the tokamak fusion system is assessed using a range of core physics and toroidal field magnet performance constraints to better understand which parameters most strongly influence the achievable fusion performance. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

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SAADAT, SH, M. SALEM, M. GHORANNEVISS, and P. KHORSHID. "Stochastic modeling of plasma mode forecasting in tokamak." Journal of Plasma Physics 78, no. 2 (November 11, 2011): 99–104. http://dx.doi.org/10.1017/s0022377811000456.

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AbstractThe structure of magnetohydrodynamic (MHD) modes has always been an interesting study in tokamaks. The mode number of tokamak plasma is the most important parameter, which plays a vital role in MHD instabilities. If it could be predicted, then the time of exerting external fields, such as feedback fields and Resonance Helical Field, could be obtained. Autoregressive Integrated Moving Average (ARIMA) and Seasonal Autoregressive Integrated Moving Average are useful models to predict stochastic processes. In this paper, we suggest using ARIMA model to forecast mode number. The ARIMA model shows correct mode number (m = 4) about 0.5 ms in IR-T1 tokamak and equations of Mirnov coil fluctuations are obtained. It is found that the recursive estimates of the ARIMA model parameters change as the plasma mode changes. A discriminator function has been proposed to determine plasma mode based on the recursive estimates of model parameters.

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Mitrishkin, Yuri V., Valerii I. Kruzhkov, and Pavel S. Korenev. "Methodology of Plasma Shape Reachability Area Estimation in D-Shaped Tokamaks." Mathematics 10, no. 23 (December 5, 2022): 4605. http://dx.doi.org/10.3390/math10234605.

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This paper suggests and develops a new methodology of estimation for a multivariable reachability region of a plasma separatrix shape on the divertor phase of a plasma discharge in D-shaped tokamaks. The methodology is applied to a spherical Globus-M/M2 tokamak, including the estimation of a controllability region of a vertical unstable plasma position on the basis of the experimental data. An assessment of the controllability region and the reachability region of the plasma is important for the design of tokamak poloidal field coils and the synthesis of a plasma magnetic control system. When designing a D-shaped tokamak, it is necessary to avoid the small controllability region of the vertically unstable plasma, because such cases occur in practice at a restricted voltage on a horizon field coil. To make the estimations mentioned above robust, PID-controllers for vertical and horizontal plasma position control were designed using the Quantitative Feedback Theory approach, which stabilizes the system and provides satisfactory control indexes (stability margins, setting time, overshoot) during plasma discharges. The controllers were tested on a series of plasma models and nonlinear models of current inverters in auto-oscillation mode as actuators for plasma position control. The estimations were made on these models, taking into account limitations on control actions, i.e., voltages on poloidal field coils. This research is the first step in the design of the plasma shape feedback control system for the operation of the Globus-M2 spherical tokamak. The developed methodology may be used in the design of poloidal field coil systems in tokamak projects in order to avoid weak achievability and controllability regions in magnetic plasma control. It was found that there is a strong cross-influence from the PF-coils currents and the CC current on the plasma shape; hence, these coils should be used to control the plasma shape simultaneously.

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Bishop, Chris M., Paul S. Haynes, Mike E. U. Smith, Tom N. Todd, and David L. Trotman. "Real-Time Control of a Tokamak Plasma Using Neural Networks." Neural Computation 7, no. 1 (January 1995): 206–17. http://dx.doi.org/10.1162/neco.1995.7.1.206.

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In this paper we present results from the first use of neural networks for real-time control of the high-temperature plasma in a tokamak fusion experiment. The tokamak is currently the principal experimental device for research into the magnetic confinement approach to controlled fusion. In an effort to improve the energy confinement properties of the high-temperature plasma inside tokamaks, recent experiments have focused on the use of noncircular cross-sectional plasma shapes. However, the accurate generation of such plasmas represents a demanding problem involving simultaneous control of several parameters on a time scale as short as a few tens of microseconds. Application of neural networks to this problem requires fast hardware, for which we have developed a fully parallel custom implementation of a multilayer perceptron, based on a hybrid of digital and analogue techniques.

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Costley, A. E. "Towards a compact spherical tokamak fusion pilot plant." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2141 (February 4, 2019): 20170439. http://dx.doi.org/10.1098/rsta.2017.0439.

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The question of size of a tokamak fusion reactor is central to current fusion research especially with the large device, ITER, under construction and even larger DEMO reactors under initial engineering design. In this paper, the question of size is addressed initially from a physics perspective. It is shown that in addition to size, field and plasma shape are important too, and shape can be a significant factor. For a spherical tokamak (ST), the elongated shape leads to significant reductions in major radius and/or field for comparable fusion performance. Further, it is shown that when the density limit is taken into account, the relationship between fusion power and fusion gain is almost independent of size, implying that relatively small, high performance reactors should be possible. In order to realize a small, high performance fusion module based on the ST, feasible solutions to several key technical challenges must be developed. These are identified and possible design solutions outlined. The results of the physics, technical and engineering studies are integrated using the Tokamak Energy system code, and the results of a scoping study are reviewed. The results indicate that a relatively small ST using high temperature superconductor magnets should be feasible and may provide an alternative, possibly faster, ‘small modular’ route to fusion power. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

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O’Shea, Finn H., Semin Joung, David R. Smith, and Ryan Coffee. "Automatic identification of edge localized modes in the DIII-D tokamak." APL Machine Learning 1, no. 2 (June 1, 2023): 026102. http://dx.doi.org/10.1063/5.0134001.

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Fusion power production in tokamaks uses discharge configurations that risk producing strong type I edge localized modes. The largest of these modes will likely increase impurities in the plasma and potentially damage plasma facing components, such as the protective heat and particle divertor. Machine learning-based prediction and control may provide for the automatic detection and mitigation of these damaging modes before they grow too large to suppress. To that end, large labeled datasets are required for the supervised training of machine learning models. We present an algorithm that achieves 97.7% precision when automatically labeling edge localized modes in the large DIII-D tokamak discharge database. The algorithm has no user controlled parameters and is largely robust to tokamak and plasma configuration changes. This automatically labeled database of events can subsequently feed future training of machine learning models aimed at autonomous edge localized mode control and suppression.

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Nowak vel Nowakowski, P., D. Makowski, B. Jabłoński, P. Szajerski, Santosh P. Pandya, R. O’Connor, R. Tieulent, and R. Barnsley. "Evaluation of optical transmission across the ITER hard x-ray monitor system designed for the first plasma scenarios." Review of Scientific Instruments 93, no. 10 (October 1, 2022): 103512. http://dx.doi.org/10.1063/5.0101802.

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Hard x-ray (HXR) spectroscopy is applied for diagnostics of runaway electrons in nuclear fusion reactors. The scintillation counter is one of the most commonly used types of detectors for HXR spectroscopy. It consists of a detector that emits light when excited by HXR radiation (scintillator) directly coupled to a PMT (Photomultiplier Tube) that converts light pulses into an electrical signal. This type of detector is commonly used in existing tokamaks, such as Joint European Torus (JET), Experimental Advanced Superconducting Tokamak (EAST), Compact Assembly (COMPASS), and Axially Symmetric Divertor Experiment (ASDEX-U). In all these cases, the scintillator is directly coupled to the PMT to provide the best possible light transmission efficiency. The Hard X-ray Monitor (HXRM) is one among the first plasma diagnostic systems at ITER that provides information about the energy distribution of runaway electrons inside a tokamak by HXR spectroscopy. This system also uses a scintillator and a PMT as a detector. Due to the heavy shielding of the blanket modules, vacuum vessel, and port-plugs, it is not possible to assemble the scintillator outside the tokamak vacuum vessel. The PMT detector cannot be installed in the close vicinity of the tokamak due to either the significant magnetic field or temperature. A possible solution is to decouple the scintillator from the PMT and place the PMT inside the port-cell. Light pulses will be transmitted to the PMT via a 12 m long optical fiber bundle. Evaluation of the optical transmission was carried out to assess the performance of the HXR monitor and verify possible problems related to the PMT pulse discrimination under low light conditions.

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Sorokina, Daria, Ilya Senichenkov, Elena Vekshina, and Vladimir Rozhansky. "Testing of the SOLPS-ITER code at Globus-M2 spherical tokamak with detached divertor." MATEC Web of Conferences 245 (2018): 13003. http://dx.doi.org/10.1051/matecconf/201824513003.

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In according to a present understanding of Scrape-Off Layer (SOL) physics, future thermonuclear devices like ITER, DEMO and beyond, require high radiation regimes in order to reduce heat loads on tokamak divertor. Recent experiments at ASDEX Upgrade, JET and other tokamaks demonstrated that such regimes might be achieved by the seeding of the radiative impurities. In the present paper the modeling of the high radiation regimes and the transition to the detachment at the Globus-M2 spherical tokamak is performed by the SOLPS-ITER transport code. The obtained modeling results for GLobus-M2 tokamak demonstrate the trend similar to what is observed at larger machines, e.g. AUG and JET. The significant reduction of peak power density at the outer target plate and transition to the detachment with High Field Side High Density (HFSHD) formation at the inner plate was achieved with impurity seeding rate almost equal to the deuterium puff (in el/sec). However, unlike AUG, further increasing of the seeding rate leads not to a formation of the radiative X-point, but to a radiative collapse. This is caused by smaller machine size, which allows the impurity neutrals to penetrate easier into the confined region. It was noticed that starting with attached divertor the inner target transits to the detachment earlier than the outer one.

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30

Hu, Youjun, Matthew Miecnikowski, Yang Chen, and Scott Parker. "Fully Kinetic Simulation of Ion-Temperature-Gradient Instabilities in Tokamaks." Plasma 1, no. 1 (May 31, 2018): 105–18. http://dx.doi.org/10.3390/plasma1010010.

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The feasibility of using full ion kinetics, instead of gyrokinetics, in simulating low-frequency Ion-Temperature-Gradient (ITG) instabilities in tokamaks has recently been demonstrated. The present work extends the full ion kinetics to the nonlinear regime and investigates the nonlinear saturation of a single-n ITG instability due to the E × B trapping mechanism (n is the toroidal mode number). The saturation amplitude predicted by the E × B trapping theory is found to agree with the saturation level observed in the simulation. In extending to the nonlinear regime, we developed a toroidal Boris full orbit integrator, which proved to be accurate in capturing both the short-time scale cyclotron motion and long time scale drift motion, with good kinetic energy conservation and toroidal angular momentum conservation in tokamak equilibrium magnetic fields. This work also extends the previous work from analytic circular magnetic equilibria to general numerical magnetic equilibria, enabling simulation of realistic equilibria reconstructed from tokamak experiments.

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CHEN, Z. Y., B. N. WAN, Y. J. SHI, H. J. JU, J. X. ZHU, and H. F. LIANG. "Resonant interaction of runaway electrons with magnetic field ripple in tokamak plasmas." Journal of Plasma Physics 75, no. 5 (October 2009): 669–74. http://dx.doi.org/10.1017/s0022377809007843.

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AbstractThe toroidal magnetic field of tokamaks is generated by a finite number of coils, which slightly modulates the magnetic field and runaway electrons experience this modulation. The resonant interaction between runaway electrons and the magnetic field ripple has been observed in the HT-7 tokamak. The maximum energy of runaways in the edge region could be blocked by the resonance of gyromotion with the nth harmonic of the magnetic field ripple. This resonant interaction is favorable for the control of runaway energy.

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32

Segura, Javier Lopez, Nicolas Urgoiti Moinot, and Enzo Lazzaro. "Simulation of a high proton temperature plasma toroidal magnetic trap to be used in proton-11B fusion." Journal of Technological and Space Plasmas 1, no. 1 (November 20, 2019): 12–20. http://dx.doi.org/10.31281/jtsp.v1i1.6.

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Several tokamaks structures containing 500 keV protons to be used in P-B11 fusion were simulated. In order to find the optimal confinement configuration, the simulation was helped by an evolutionary algorithm running 145,000 simulations. The results are presented in this paper. According to the simulations the tokamak structure can be operated to reach ignition using the proposed plasma mode that includes the use of low electron temperature and high thermal energy protons in the plasma (500 keV).

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Rastovic, Danilo. "Fractional variational problems and particle in cell gyrokinetic simulations with fuzzy logic approach for tokamaks." Nuclear Technology and Radiation Protection 24, no. 2 (2009): 138–44. http://dx.doi.org/10.2298/ntrp0902138r.

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In earlier Rastovic's papers [1] and [2], the effort was given to analyze the stochastic control of tokamaks. In this paper, the deterministic control of tokamak turbulence is investigated via fractional variational calculus, particle in cell simulations, and fuzzy logic methods. Fractional integrals can be considered as approximations of integrals on fractals. The turbulent media could be of the fractal structure and the corresponding equations should be changed to include the fractal features of the media.

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34

Shukla, Braj Kishore, Jatin Patel, Harshida Patel, Dharmesh Purohit, Hardik Mistry, and K. G. Parmar. "ECRH experiments on Tokamaks SST-1 & Aditya-U and ECRH upgradation plan for SST-1." EPJ Web of Conferences 277 (2023): 02005. http://dx.doi.org/10.1051/epjconf/202327702005.

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A 42GHz-500kW ECRH system [1-6] is used to carry out various experiments related to plasma breakdown and ECR heating on tokamaks SST-1 and Aditya-U. The system has been upgraded with new anode modulator power supply to launch two ECRH pulses to carry out breakdown and heating simultaneously. In SST-1, ECRH system is used routinely for plasma breakdown at fundamental harmonic, approximately 150kW power is launched for 70ms to 150ms duration and consistent plasma start-up is achieved in SST-1. In the recent experiments, second EC pulse is also launched at the plasma flat-top to heat the plasma, some heating signatures are seen but more experiments will be carried out to confirm the plasma heating with ECRH. In Aditya-U tokamak, simultaneous plasma breakdown and heating experiments are carried out successfully [2]. In the first pulse around 100kW power in fundamental O-mode is launched for 70ms duration for the breakdown at low-loop voltage and around 150kW ECRH power for 50ms duration is launched in second EC pulse to heat the plasma. In case of Aditya-U, plasma heating is observed clearly as soft X-ray signal increases sharply with ECRH. In AdityaU tokamak, deuterium plasma experiments have been carried out and ECRH launched at the flat-top of deuterium plasma current. In deuterium plasma also ECR heating is observed as soft X-ray signal increases with ECH power. For SST-1, ECRH system is being upgraded with another 82.6GHz system, this system would be used to carry out plasma heating and start-up at second harmonic. The 82.6GHz system is already connected with the SST-1 tokamak, the old 82.6GHz-200kW Gyrotron will be upgraded to 400kW system to carry out effective heating experiments on SST-1 at higher ECRH power. The paper discusses the recent results of ECRH experiments carried out on tokamaks SST-1 & Aditya-U and presents the upgradation plan of EC system for SST-1.

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35

Konkov, A. E., P. S. Korenev, Yu V. Mitrishkin, I. M. Balachenkov, and E. O. Kiselev. "Real-Time Plasma Magnetic Control System with Equilibrium Reconstruction Algorithm in the Feedback for the Globus-M2 Tokamak." Физика плазмы 49, no. 12 (December 1, 2023): 1348–56. http://dx.doi.org/10.31857/s0367292123600760.

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To control the plasma shape during a tokamak discharge, it is necessary to calculate the plasmashape in real-time. The rate requirements for the shape calculations are especially high for tokamaks with asmall radius, such as Globus-M2 (St. Petersburg, Russia). A real-time magnetic plasma control system forthe Globus-M2 tokamak with flux and current distribution identification (FCDI) algorithm for the plasmaequilibrium reconstruction in feedback is presented. The control system contains discrete one-dimensionaland matrix proportional-integral-derivative controllers synthesized by the matrix inequality method usingthe plasma LPV model calculated on experimental data, and carries out the coordinated control of the plasmaposition and shape as well as the compensation for the scattered field of the central solenoid. The FCDI algorithmis improved for the operation in the real-time mode, and makes it possible to reconstruct the plasmashape in 20 μs. The digital control system with a feedback algorithm was simulated on a real-time test bench,consisting of two Speedgoat Performance Real-Time Target Machines (RTTM), and demonstrated the averageTask Execution Time (TET) value in 67 μs.

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Takase, Y., M. Kikuchi, T. Maekawa, M. Matsukawa, M. Nagata, S. Nishio, Y. Ono, K. N. Sato, and K. Tobitaa. "Tokamak and Spherical Tokamak Research in Japan." Fusion Science and Technology 51, no. 2T (February 2007): 46–51. http://dx.doi.org/10.13182/fst07-a1311.

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37

Sadowski, Marek J. "Selected methods of electron-and ion-diagnostics in tokamak scrape-off-layer." Nukleonika 60, no. 2 (June 1, 2015): 199–206. http://dx.doi.org/10.1515/nuka-2015-0039.

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Abstract This invited paper considers reasons why exact measurements of fast electron and ion losses in tokamaks, and particularly i n a scrape-off-layer and near a divertor region, are necessary in order to master nuclear fusion energy production. Attention is also paid to direct measurements of escaping fusion products from D-D and D-T reactions, and in particular of fast alphas which might be used for plasma heating. The second part describes the generation of so-called runaway and ripple-born electrons which might induce high energy losses and cause severe damages of internal walls in fusion facilities. Advantages and disadvantages of different diagnostic methods applied for studies of such fast electrons are discussed. Particular attention is paid to development of a direct measuring technique based on the Cherenkov effect which might be induced by fast electrons in appropriate radiators. There are presented various versions of Cherenkov-type probes which have been developed by the NCBJ team and applied in different tokamak experiments. The third part is devoted to direct measurements of fast ions (including those produced by the nuclear fusion reactions) which can escape from a high-temperature plasma region. Investigation of fast fusion-produced protons from tokamak discharges is reported. New ion probes, which were developed by the NCBJ team, are also presented. For the first time there is given a detailed description of an ion pinhole camera, which enables irradiation of several nuclear track detectors during a single tokamak discharge, and a miniature Thomson-type mass-spectrometer, which can be used for ion measurements at plasma borders.

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38

Zohm, Hartmut. "On the size of tokamak fusion power plants." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2141 (February 4, 2019): 20170437. http://dx.doi.org/10.1098/rsta.2017.0437.

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Figures of merit for future tokamak fusion power plants (FPPs) are presented. It is argued that extrapolation from present-day experiments to proposed FPPs must follow a consistent development path, demonstrating the largest required leaps in intermediate devices to allow safe extrapolation to an FPP. This concerns both plasma physics and technology. At constant plasma parameters, the figures of merit depend on both major radius R and magnetic field B . We propose to use the term ‘size’ for a combination of R and B to avoid ambiguities in scaling arguments. Two routes to FPPs are discussed: the more conventional one increasing R , based on the assumption that B is limited by present technology; and an alternative approach assuming the availability of new technology for superconducting coils, allowing higher B . It is shown that the latter will lead to more compact devices, and, assuming a criterion based on divertor impurity concentration, is in addition more favourable concerning the exhaust problem. However, in order to obtain attractive steady-state tokamak FPPs, the required plasma parameters still require considerable progress with respect to present experiments. A credible strategy to arrive at these must hence be shown for both paths. In addition, the high-field path needs a demonstration of the critical technology items early on. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

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39

Donnelly, I. J., and B. E. Clancy. "Kinetic theory of Alfvén waves in plasmas with force-free currents." Journal of Plasma Physics 45, no. 2 (April 1991): 213–28. http://dx.doi.org/10.1017/s0022377800015658.

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Equations are derived for the kinetic-theory analysis of small-amplitude Alfvén waves in cylindrical plasmas carrying force-free currents. The equations, which include ion Larmor-radius effects to second order, are applicable to reversed-field pinches as well as to tokamaks. Fourier mode amplitudes are derived for model antennas with radial current feeds, and a quantitative analysis is made of the antenna resistance and the wave density fields in a small tokamak during Alfvén-wave heating. The effect of the plasma current on the wave thermal energy flux is discussed.

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40

Song, Yuxuan. "The progress and current status of Tokamak: a systematic review." E3S Web of Conferences 292 (2021): 02067. http://dx.doi.org/10.1051/e3sconf/202129202067.

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Nuclear fusion energy is an ideal energy source for the future due to the clean and efficient features, first proposed by Russian scientists in the 1950s. With the successful construction and operation of a batch of tokamak devices globally, a series of major achievements have been realized in magnetic confinement fusion (MF). On this basis, the recent progress and current status of tokamak devices are systematically reviewed from academic literatures and official websites. To better demonstrate, the principle of MF and the history of a tokamak are introduced firstly. Subsequently, developments of four typical state-of-art tokamak facilities (JT60, FTFR, JET, EAST) are discussed detailly. These results offer a guideline for tokamak device construction and MCF realization.

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41

Shu, Shuangbao, Tianqi Wu, Ziqiang Yang, Jianhua Yang, Yuzhong Zhang, Ziyi Wang, and Huajun Liang. "Measurements of emissivity and temperature for polarized long-wavelength infrared light from tungsten under simulating tokamak conditions." Review of Scientific Instruments 93, no. 11 (November 1, 2022): 113532. http://dx.doi.org/10.1063/5.0101504.

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Tungsten is regarded as the baseline first wall material in tokamaks. This work provides a polarized method for measuring the emissivity and temperature of the tungsten using an infrared camera and a polarizer under simulating tokamak conditions. In the experiment, a polarizer with an adjustable polarization direction is set up in front of an infrared camera. A rotatable fixture is used to fix the sample and change the angle between the surface and the normal. The sample is rotated from 0° to 80°, and the polarized emissivity first increases and then decreases with increasing rotation angle. The uncertainty in emissivity resulting from this polarized method and non-polarized method is analyzed. To compare the effects of the polarized method and the non-polarized method, the rotation angle is adjusted to 0°, and a fitting model is used to describe the relationship between emissivity and temperature. Errors between the calculated temperature and measured temperature are used as a scale, and the polarized method improves the accuracy of temperature measurement. This polarized method provides a technical way to measure the emissivity and temperature in a tokamak and can be applied in other similar applications.

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42

Montani, Giovanni, Nakia Carlevaro, and Brunello Tirozzi. "On the Turbulent Behavior of a Magnetically Confined Plasma near the X-Point." Fluids 7, no. 5 (April 29, 2022): 157. http://dx.doi.org/10.3390/fluids7050157.

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We construct a model for the turbulence near the X-point of a Tokamak device and, under suitable assumptions, we arrive to a closed equation for the electric field potential fluctuations. The analytical and numerical analysis is focused on a reduced two-dimensional formulation of the dynamics, which allows a direct mapping to the incompressible Navier-Stokes equation. The main merit of this study is to outline how the turbulence near the X-point, in correspondence to typical operation conditions of medium and large size Tokamaks, is dominated by the enstrophy cascade from large to smaller spatial scales.

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43

Буланин, В. В., В. К. Гусев, Г. С. Курскиев, В. Б. Минаев, М. И. Патров, А. В. Петров, Ю. В. Петров, and А. Ю. Яшин. "Применение метода многочастотного допплеровского обратного рассеяния для исследования альфвеновских мод в токамаке." Письма в журнал технической физики 45, no. 21 (2019): 44. http://dx.doi.org/10.21883/pjtf.2019.21.48474.17982.

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The results of the study of toroidal Alfven modes (TAE) using the multi-frequency Doppler backscattering (DBS) in the Globus-M tokamak are presented. The article is focused on the presentation of the Alfven mode registration method for multichannel probing. The possible causes of the observed oscillations of the poloidal plasma rotation velocity at the Alfvén oscillation frequencies are discussed in detail. The data on the spatial distribution of Alfvén modes revealed by multi-frequency DBS are given. The recommendations for the further development of the DBS with the aim of a more detailed study of TAE in tokamaks were determined.

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44

Catto, Peter J., and R. D. Hazeltine. "Isothermal tokamak." Physics of Plasmas 13, no. 12 (December 2006): 122508. http://dx.doi.org/10.1063/1.2403090.

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45

Agnew, Harold M. "Tokamak Applications." Physics Today 38, no. 7 (July 1985): 13. http://dx.doi.org/10.1063/1.2814627.

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46

Shanny, Ramy A., and Harold P. Furth. "Tokamak History." Physics Today 38, no. 8 (August 1985): 78. http://dx.doi.org/10.1063/1.2814675.

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47

Galambos, J. D., L. J. Perkins, S. W. Haney, and J. Mandrekas. "Commercial tokamak reactor potential with advanced tokamak operation." Nuclear Fusion 35, no. 5 (May 1995): 551–73. http://dx.doi.org/10.1088/0029-5515/35/5/i06.

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48

Kurnaev, V. A., V. E. Nikolaeva, S. A. Krat, E. D. Vovchenko, A. V. Kaziev, A. S. Prishvitsyn, G. M. Vorob'ev, T. V. Stepanova, and D. S. Gvozdevskaya. "Systems of in situ diagnostics of plasma-surface interaction in MEPHIST-1 tokamak." Izvestiya vysshikh uchebnykh zavedenii. Fizika 64, no. 1 (2021): 118–24. http://dx.doi.org/10.17223/00213411/64/1/118.

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In the Institute for Laser and Plasma Technologies of NRNU MEPhI a compact spherical tokamak MEPhIST (MEPhI-Spherical Tokamak) for educational, demonstration and research purposes is under development and construction. The creation of plasma diagnostics systems involves several stages, determined by the successive complication of the plasma researchtasks, the upgrading of the device and the development of educational and methodological material for laboratory work to be put at the tokamak. Working out in situ methods of plasma-surface interaction analysis is one of the main scientific and technological goals of this tokamak. The complex of diagnostics described in the paper provides complementary information about the processes occurring at plasma with surface contact, is a set of very informative and well-tested diagnostic tools that allow students to obtain visual and reliable information about the processes occurring in the discharge chamber of the tokamak.

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Воронин, А. В., В. Ю. Горяинов, В. В. Забродский, Е. В. Шерстнев, В. А. Корнев, П. Н. Аруев, Г. С. Курскиев, Н. А. Жубр, and А. С. Тукачинский. "Измерение электронной температуры плазмы фольговым рентгеновским спектрометром, установленным на токамаках ТУМАН-3М и Глобус-М2." Журнал технической физики 91, no. 12 (2021): 1922. http://dx.doi.org/10.21883/jtf.2021.12.51758.188-21.

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Technical solution were presented for a foil spectrometer installed on the Globus-M2 and TUMAN-3M tokamaks for measuring the electron plasma temperature. Measurements have been carried out of the time dependence of the plasma temperature in the central region of tokamaks. Using of integrated photodetectors and unique beryllium foils with a thickness of 14–80 µm made it possible to increase the sensitivity of the spectrometer. An important quality of the foils used were the increased values of strength, plasticity, homogeneity, and the absence of surface and internal defects. The combined use of the spectrometer with Thomson scattering diagnostics made it possible to carry out regular temperature measurements in the Globus-M2 tokamak with a high spatial and temporal resolution. The influence of impurities is estimated on the measurement of the electron temperature of the plasma.

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Yashin, Alexander, Alexander Belokurov, Leonid Askinazi, Alexander Petrov, and Anna Ponomarenko. "The Influence of Fast Particles on Plasma Rotation in the TUMAN-3M Tokamak." Atoms 10, no. 4 (October 1, 2022): 106. http://dx.doi.org/10.3390/atoms10040106.

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In most present-day tokamaks, the majority of the heating power comes from sources such as neutral-beam injection (NBI) and other types of auxiliary heating which allow for the transfer of energy to the plasma by a small population of externally introduced fast particles. The behavior of the fast ions is important for the overall plasma dynamics, and understanding their influence is vital for the success of any future magnetic confinement devices. In the TUMAN-3M tokamak, it has been noted that the loss of fast particles during NBI can lead to dramatic changes in the rotation velocity profiles, as they are responsible for the negative radial electric field on the periphery.

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Journal articles on the topic 'Tokamak'

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