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Journal articles on the topic "Runaway Electron"

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Breizman, B. N., and D. I. Kiramov. "Marginal stability constraint on runaway electron distribution." Physics of Plasmas 30, no. 2 (February 2023): 022301. http://dx.doi.org/10.1063/5.0130558.

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High-frequency kinetic instabilities of the strongly anisotropic runaway electrons (RE) can enhance the pitch-angle scattering of the runaways significantly. This wave-induced scattering can easily prevail over runaway scattering on high-Z impurities. In a steady state, collisional damping balances the kinetic drive of the unstable waves, keeping the RE distribution function at marginal stability. The marginal stability constraint limits the achievable RE densities and the shape of the RE distribution function. In this study, we consider whistler and compressional Alfvén waves as the primary source of enhanced elastic scattering of the runaways. By balancing the anomalous Doppler resonance drive with the collisional wave damping, we find the RE distribution function in the ultra-relativistic range of the phase space. We also derive an expression for the spectral energy density of the waves. We show that the power needed to compensate for the wave dissipation is negligible compared to the work of the electric field. The latter is in balance with the synchrotron losses of the runaway electrons.
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Vlainic, Milos, Ondrej Ficker, Jan Mlynar, and Eva Macusova. "Experimental Runaway Electron Current Estimation in COMPASS Tokamak." Atoms 7, no. 1 (January 16, 2019): 12. http://dx.doi.org/10.3390/atoms7010012.

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Runaway electrons present a potential threat to the safe operation of future nuclear fusion large facilities based on the tokamak principle (e.g., ITER). The article presents an implementation of runaway electron current estimations at COMPASS tokamak. The method uses a theoretical method developed by Fujita et al., with the difference in using experimental measurements from EFIT and Thomson scattering. The procedure was explained on the COMPASS discharge number 7298, which has a significant runaway electron population. Here, it was found that at least 4 kA of the plasma current is driven by the runaway electrons. Next, the method aws used on the set of plasma discharges with the variable electron plasma density. The difference in the plasma current was explained by runaway electrons, and their current was estimated using the aforementioned method. The experimental results are compared with the theory and simulation. The comparison presented some disagreements, showing the possible direction for the code development. Additional application on runaway electron energy limit is also addressed.
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YANG, JIN-WEI, YI-PO ZHANG, XU LI, XIAN-YING SONG, GUO-LIANG YUAN, MIN LIAO, LI-QUN HU, SHI-YAO LIN, and QING-WEI YANG. "Suppression of runaway electrons during electron cyclotron resonance heating on HL-2A tokamak." Journal of Plasma Physics 76, no. 1 (September 10, 2009): 75–85. http://dx.doi.org/10.1017/s0022377809990250.

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AbstractThe statistical analysis of heating effect and the cross-correlation analysis of both electron temperature and loop voltage have been done during electron cyclotron resonance heating (ECRH). The behavior of runaway electrons in the flat-top phase during ECRH are analyzed using experimental data. It is shown that the runaway population is indeed suppressed or even quenched when the toroidal electric field ET is reduced below the threshold electric field Eth by high-power and long-duration ECRH. The physical mechanism of runaway suppression is explored by the resonant interaction between the electron cyclotron waves and the energetic runaway electrons.
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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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Lisenkov, V. V., Yu I. Mamontov, and I. N. Tikhonov. "Numerical investigation of a high-pressure gas medium preionization by runaway electrons." Journal of Physics: Conference Series 2064, no. 1 (November 1, 2021): 012021. http://dx.doi.org/10.1088/1742-6596/2064/1/012021.

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Abstract A comparative simulation of the generation and acceleration of runaway electrons in the discharge gap during the initiation of the discharge by nanosecond and subnanosecond pulses is carried out. We used a numerical model based on the PIC-MCC method. Calculations were carried out for N2 6 atm pressure. Numerical simulation of a formation process of the electron avalanche initiated by an electron field-emitted from the top of the cathode microspike was carried out taking into account the motion of each electron in the avalanche. Characteristic runaway electron trajectories, runaway electron energy gained during the motion through the discharge gap, times required for runaway electrons to reach the anode were calculated. We compared our results with calculations using well-known differential equation of electron acceleration using braking force in Bethe approximation. We solved this equation also for braking force based on real (experimental) ionization cross section. The reasons for the discrepancy in the calculation results are discussed.
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KOMIRENKO, S. M., K. W. KIM, V. A. KOCHELAP, and M. A. STROSCIO. "HIGH-FIELD ELECTRON TRANSPORT CONTROLLED BY OPTICAL PHONON EMISSION IN NITRIDES." International Journal of High Speed Electronics and Systems 12, no. 04 (December 2002): 1057–81. http://dx.doi.org/10.1142/s0129156402001927.

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We have investigated the problem of electron runaway at strong electric fields in polar semiconductors focusing on the nanoscale nitride-based heterostructures. A transport model which takes into account the main features of electrons injected in short devices under high electric fields is developed. The electron distribution as a function of the electron momenta and coordinate is analyzed. We have determined the critical field for the runaway regime and investigated this regime in detail. The electron velocity distribution over the device is studied at different fields. We have applied the model to the group-III nitrides: InN, GaN and AlN. For these materials, the basic parameters and characteristics of the high-field electron transport are obtained. We have found that the transport in the nitrides is always dissipative. However, in the runaway regime, energies and velocities of electrons increase with distance which results in average velocities higher than the peak velocity in bulk-like samples. We demonstrated that the runaway electrons are characterized by the extreme distribution function with the population inversion. A three-terminal heterostructure where the runaway effect can be detected and measured is proposed. We also have considered briefly different nitride-based small-feature-size devices where this effect can have an impact on the device performance.
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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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Zubarev, Nikolay M., Olga V. Zubareva, and Michael I. Yalandin. "Features of Electron Runaway in a Gas Diode with a Blade Cathode." Electronics 11, no. 17 (September 2, 2022): 2771. http://dx.doi.org/10.3390/electronics11172771.

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Conditions for electron runaway in a gas diode with a blade cathode providing a strongly inhomogeneous distribution of the electric field in the interelectrode gap have been studied theoretically. It has been demonstrated that the character of electron runaway differs qualitatively for cathodes with a different rounding radius of the edges. In the case of a relatively large edge radius (tens of microns or more), the conditions for the transition of electrons to the runaway mode are local in nature: they are determined by the field distribution in the immediate vicinity of the cathode where the electrons originate from. Here, the relative contribution of the braking force acting on electrons in a dense gas reaches a maximum. This behavior is generally similar to the behavior of electrons in a uniform field. For a cathode with a highly sharpened edge, the relative contribution of the braking force is maximum in the near-anode region. As a consequence, the runaway condition acquires a nonlocal character: it is determined by the electron dynamics in the entire interelectrode gap.
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Zhang, Cheng, Jianwei Gu, Ruexue Wang, Hao Ma, Ping Yan, and Tao Shao. "Simulation of runaway electron inception and breakdown in nanosecond pulse gas discharges." Laser and Particle Beams 34, no. 1 (November 23, 2015): 43–52. http://dx.doi.org/10.1017/s0263034615000944.

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AbstractNanosecond pulse discharges can provide high reduced electric field for exciting high-energy electrons, and the ultrafast rising time of the applied pulse can effectively suppress the generation of spark streamer and produce homogeneous discharges preionized by runaway electrons in atmospheric-pressure air. In this paper, the electrostatic field in a tube-plate electrodes gap is calculated using a calculation software. Furthermore, a simple physical model of nanosecond pulse discharges is established to investigate the behavior of the runaway electrons during the nanosecond pulse discharges with a rise time of 1.6 ns and a full-width at half-maximum of 3–5 ns in air. The physical model is coded by a numerical software, and then the runaway electrons and electron avalanche are investigated under different conditions. The simulated results show that the applied voltage, voltage polarity, and gas pressure can significantly affect the formation of the avalanche and the behavior of the runaway electrons. The inception time of runaway breakdown decreases when the applied voltage increases. In addition, the threshold voltage of runaway breakdown has a minimum value (10 kPa) with the variation of gas pressure.PACS: 52.80.-s
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Babich, Leonid P. "Relativistic runaway electron avalanche." Uspekhi Fizicheskih Nauk 190, no. 12 (April 2020): 1261–92. http://dx.doi.org/10.3367/ufnr.2020.04.038747.

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Dissertations / Theses on the topic "Runaway Electron"

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DAL, MOLIN ANDREA. "Reconstruction of the velocity space of runaway electrons by spectral measurements of the hard x-ray emission in tokamaks." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/304289.

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La crescita delle instabilità del plasma può causare un'improvvisa perdita di energia termica e magnetica. In questi eventi disruttivi, gli elettroni possono venire accelerati a energie relativistiche e ottenere una frazione significativa dell'energia immagazzinata nel campo magnetico del tokamak. A queste velocità, le collisioni Coulombiane con il plasma di background diventano trascurabili e l'accelerazione dei runaway electrons è limitata solamente da effetti relativistici e perdite radiative. Quando il confinamento viene perso, il fascio energetico di runaway electrons può collidere con le componenti all'interno della camera da vuoto causando gravi danni. Gli eventi non mitigati di runaway electrons possono forzare lunghi periodi di arresto della durata di diversi mesi per consentire le riparazioni. Evitare questi scenari estremi è fondamentale per il successo di tokamak come ITER. Durante le disruzioni, i runaway electrons possono essere accelerati fino a energie nell'ordine di diversi MeV. Uno dei meccanismi che limitano questa accelerazione è l'emissione di radiazione di bremsstrahlung, causata dall'interazione delle particelle relativistiche con il plasma di background. A causa dell’elevata energia di questi elettroni, lo spettro della radiazione bremsstrahlung si estende fino a diversi MeV, nell’ intervallo di energia dei raggi X duri. Questo lavoro illustra come si possa ricostruire lo spazio di velocità dei runaway electrons dall'emissione di bremsstrahlung misurata. Nella prima metà di questo lavoro vengono discussi lo sviluppo, la caratterizzazione e l'implementazione di nuovi spettrometri a raggi X duri ottimizzati per la misura di bremsstrahlung da runaway electrons. Un nuovo spettrometro HXR compatto, con capacità di conteggio superiori a 1 Mcps, è stato sviluppato per il sistema Gamma-Ray Imager del tokamak DIII-D. Questo rivelatore si basa su un cristallo scintillatore YAP: Ce accoppiato con un fotomoltiplicatore di silicio. L'energia del rivelatore ha un ampio intervallo dinamico superiore a 20 MeV e una risoluzione energetica di circa il 9% a 661,7 keV. Il design di questo dispositivo è stato guidato dai risultati sperimentali raccolti a DIII-D con un precedente prototipo, basato su un cristallo scintillatore LYSO: Ce accoppiato con un fotomoltiplicatore di silicio. In questa sezione della tesi viene inoltre presentato lo sviluppo del Runaway Electron GAmma-Ray Detection System (REGARDS). REGARDS è un nuovo spettrometro HXR portatile a progettato per la misurazione della bremsstrahlung dei runaway electrons. Il rivelatore è basato su un cristallo scintillatore LaBr3: Ce accoppiato a un tubo fotomoltiplicatore. Il sistema ha un ampio intervallo dinamica per la spettroscopia HXR con un limite in energia superiore superiore a 20 MeV e una risoluzione energetica di circa il 3% a 661,7 keV. Il guadagno del rivelatore HXR di REGARDS è monitorato da un sistema di controllo esterno. REGARDS è stato utilizzato presso i tokamaks AUG e COMPASS. Nella seconda metà di questa tesi viene discussa l'analisi degli esperimenti di runaway electrons eseguiti presso i tokamaks AUG e JET. Un modello completo dell'emissione di bremsstrahlung è stato creato utilizzando il codice GENESIS e la funzione di risposta degli spettrometri HXR è stata generata utilizzando MCNP. La regolarizzazione di Tikhonov viene utilizzata per ricostruire la funzione di distribuzione dell'energia dei runaway electrons dalle misurazioni. Le funzioni di distribuzione di energia dei runaway electrons ricostruite consentono una descrizione quantitativa del fascio durante la scarica. Le informazioni raccolte con queste tecniche sono cruciali per comprendere la formazione di runaway electrons, per validare i modelli da principi primi e per valutare l'efficacia di diverse tecniche di mitigazione degli runaway electrons come la massive gas injection, la shattered pellet injection e la resonant magnetic perturbation.
The growth of plasma instabilities can cause a sudden loss of thermal and magnetic energy. In this disruptive event, electrons can be accelerated to relativistic energies and gain a significant fraction of the energy stored in the tokamak magnetic field. At these velocities, Coulomb collisions with background plasma become negligible and the acceleration of the runaway electrons is only limited by relativistic effects and radiative losses. When the post-disruption magnetic field is lost, the energetic runaway electron beam can collide with the in-vessel plasma-facing components causing severe and localized damage. Unmitigated runaway electron events can hinder operation by forcing long shutdown periods of several months to allow repairs. The avoidance of these extreme scenarios is paramount to the success of large-scale tokamaks. The threat posed by runaway electrons is a primary focus of the fusion community. Extensive modelling and experimental campaigns are currently ongoing in most large and medium-scale tokamaks. During disruptions, runaway electrons can be accelerated up to energies in the order of several MeVs. One of the mechanisms that limit this acceleration is the emission of bremsstrahlung radiation caused by the interaction of the relativistic particles with the background plasma. Due to the extreme energy these electrons can reach, the bremsstrahlung radiation spectrum extends to several MeVs, in hard X-ray energy range. This work illustrates how information on the runaway electron velocity space can be extracted from the measured bremsstrahlung X-ray emission. In the first half of this work, the development, characterization and implementation of novel hard x-ray spectrometers optimized for runaway electron bremsstrahlung measurement are discussed. A new compact HXR spectrometer with high counting rate capabilities in excess of 1 MCps was developed for the array configuration of the tokamak DIII-D Gamma-Ray Imager system. This detector is based on a YAP:Ce scintillator crystal coupled with a silicon photomultiplier. The detector energy has a wide dynamic range in excess of 20 MeV and an energy resolution of approximately 9% at 661.7 keV. The design of this device was informed by the experimental results collected at DIII-D with a previous prototype based on a LYSO:Ce scintillator crystal coupled with a silicon photomultiplier. In this section, the development of the Runaway Electron GAmma-Ray Detection System (REGARDS) is also presented. REGARDS is a novel portable hard X-ray spectrometer designed for RE bremsstrahlung measurement. The detector is based on a LaBr3:Ce scintillator crystal coupled with a photomultiplier tube. The system has a wide dynamic range for HXR spectroscopy with an upper energy bound in excess of 20 MeV and an energy resolution of approximately 3% at 661.7 keV. REGARDS HXR detector gain is monitored by an external gain control system. REGARDS was deployed at the tokamaks AUG and COMPASS. In the second half of this thesis, analysis of the runaway electron experiments performed at the tokamaks AUG and JET is discussed. A full model of the bremsstrahlung emission is created using the GENESIS code and the HXR spectrometers response function is generated using MCNP. Tikhonov regularization is used to reconstruct the runaway energy distribution function from the measurements. The reconstructed runaway electron energy distribution functions allow for a quantitative description of the runaway electron beam throughout the discharge. The information collected with these techniques is crucial to understand runaway electron formation, to validate first-principle models and to evaluate the effectiveness of different runaway electron mitigation techniques such as massive gas injection (MGI), shattered pellet injection (SPI) and magnetic resonant perturbation (RMP).
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Sommariva, Cristian. "Test particles dynamics in 3D non-linear magnetohydrodynamics simulations and application to runaway electron formation in tokamak disruptions." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0512/document.

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La thèse étudie la dynamique des Electrons Découplés (DE) dans une disruption plasma déclenchée par injection massive de gaz dans le tokamak JET et simulée par le code JOREK. Cette investigation est permise par l’implémentation d’un module de suivi des particules tests relativistes dans JOREK. L’étude montre que les électrons peuvent ‘survivre’dans le chaos magnétique caractérisant la phase dite de ‘Disjonction Thermique’ (DT) de cette disruption (simulée) grâce à la reformation des surfaces magnétiques fermées. Deuxièmement, l’accélération des électrons causée par les champs électriques dus aux fluctuations magnétohydrodynamiques (MHD) pendant la DT est analysée. Cela montre que les électrons peuvent être accélérés par ces champs et devenir DE, après reconfinement, pendant la phase dite de ‘Disjonction de Courant’. Une étude préliminaire sur les dépendances entre le courant des DE et l’activité MHD dans les expériences de disruption du tokamak ASDEX Upgrade est également reportée
In view of better understanding Runaway Electron (RE) generation processes during tokamak disruptions, this work investigates test electron dynamics during a JET disruption simulated with the JOREK code. For this purpose, a JOREK module computing relativistic test particle orbits in the simulated fields has been developed and tested. The study shows that a significant fraction of pre-disruption thermal electrons remain confined in spite of the magnetic chaos characterizing the Thermal Quench (TQ) phase. This finding, which is related to the prompt reformation of closed flux surfaces after the TQ, supports the possibility of the so-called “hot tail” RE generation mechanism. In addition, it is found that electrons may be significantly accelerated during the TQ due to the presence of strong local electric field (E) fluctuations related to magnetohydrodynamic (MHD) activity. This phenomenon, which has virtually been ignored so far, may play an important role in RE generation. In connection to this modelling work, an experimental study on ASDEX Upgrade disruptions has been performed, suggesting that strong MHD activity reduces RE production
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PANONTIN, ENRICO. "Development of Nuclear Radiation Based Tomography Methods for Runaway Electrons and Fast Ions in Fusion Plasmas." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/383194.

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Lo studio degli ioni ed elettroni veloci è fondamentale per il successo della prossima generazione di tokamak di grande dimensione, come ITER, che mirano a dimostrare la possibilità di produrre energia attraverso la fusione termonucleare. Siano essi accelerati dal riscaldamento ausiliario o nati da reazioni di fusione, gli ioni possono raggiungere energie nell’ordine dei MeV. Questa energia viene poi trasmessa al plasma attraverso collisioni, aumentandone l’energia media e il rateo delle reazioni di fusione. È quindi cruciale migliorare il confinamento degli ioni veloci e sviluppare schemi di riscaldamento efficienti. Gli elettroni, invece, possono raggiungere velocità relativistiche se accelerati da campi elettrici induttivi generati durante disruzioni di plasma. Questi elettroni runaway rappresentano una minaccia per l'integrità strutturale dei tokamak di grandi dimensioni e necessitano di essere mitigati. Questa tesi tratta di metodi di deconvoluzione applicati alla ricostruzione della distribuzione delle particelle veloci a partire dall’emissione di radiazione nel range di energia del MeV. La deconvoluzione è stata declinata in due modi: unfolding della distribuzione di velocità degli elettroni runaway a partire dalla loro radiazione di bremsstrahlung, e tomografia della distribuzione di densità di ioni veloci o elettroni runaway a partire dalla misura dei loro profili di emissione fatta con linee di vista multiple. Questi algoritmi sono stati implementati in una libreria Python open source. Quattro algoritmi per l’unfolding sono stati implementati: singular value decomposition, maximum likelihood - expectation maximization, regolarizzazione di Tikhonov and di Poisson. La matrice di probabilità necessaria per svolgere queste inversioni è stata calcolata usando il codice GENESIS per stimare la probabilità di emettere fotoni di bremsstrahlung, e il codice MCNP per calcolare la funzione di risposta del detector. Queste funzioni di risposta sono state calcolate per tutte le diagnostiche hard X-ray installate nei tokamak Joint European Torus ed ASDEX Upgrade. I quattro metodi sono stati comparati su spettri sintetici e sperimentali, questi ultimi misurati ad ASDEX Upgrade. Maximum likelihood - expectation maximization si è dimostrato il più accurato sia nella ricostruzione della distribuzione in energia degli elettroni runaway, sia nel calcolo della loro energia media e massima. È stata inoltre studiato l’effetto del taglio a basse energie applicato ai dati sperimentali e il numero minimo di conteggi nello spettro necessario per svolgere una ricostruzione. In vista di una futura ricostruzione in 2D della distribuzione delle velocità degli elettroni runaway, sono state calcolate le matrici di probabilità come funzioni dell’energia e del pitch degli elettroni per tutte le diagnostiche hard X-ray installate a JET. I risultati sono presentati col formalismo delle weight-function, che permette di studiare la sensitività del detector a elettroni con energia e pitch differenti. Le matrici riportate mostrano un picco di sensitività per particelle aventi pitch-angolo uguale all’angolo racchiuso tra linea di vista del detector e il campo magnetico.
Fast particles, both electrons and ions, play an important role for the success of the next generation of large tokamak devices, such as ITER, that will prove the feasibility of magnetically confined thermonuclear fusion as an energy source. Ions accelerated by external heating or born in fusion reactions can reach energies in the MeV range. Their primary role is to sustain the plasma temperature and the fusion reaction rate, thus lots of efforts have been put into the development of efficient heating schemes and in the improvement of their confinement. On the other hand, during fast terminations of plasma pulses on tokamaks, electrons can accelerate to relativistic velocities, entering the runaway regime. Runaway electrons have enough energy to seriously damage the plasma facing components of large tokamaks, thus mitigation techniques are under study in view of ITER operations. This thesis focuses on the implementation of deconvolution techniques for the reconstruction of the fast particles distributions from their emission in the MeV energy range. The problem was approached from two different perspectives: the unfolding of the runaway electrons velocity-space distribution from spectroscopic measurements of their bremsstrahlung emission, and the tomographic reconstruction of the density distribution of both fast ions and runaway electrons from the integrated measurement of their emission performed with multiple lines of sight. These algorithms were implemented in an open source Python library. Four deconvolution algorithms were implemented for the unfolding of runaway electrons energy distribution: singular value decomposition, maximum likelihood - expectation maximization, Tikhonov regularization and Poissonian regularization. The transfer matrix necessary for this inversion was calculated using the GENESIS code for estimating the probability of bremsstrahlung emission and the MCNP code for computing the detector response function. The detector response function was calculated for all the hard X-rays diagnostics systems installed at the Joint European Torus and ASDEX Upgrade tokamaks. The performance of the four methods wes then compared over both synthetic and experimental spectra, the latter being measured at ASDEX Upgrade. Maximum likelihood - expectation maximization was found to be the most accurate in the reconstruction of both the runaway electrons energy distribution and their average and maximum energies. The robustness of the four methods against experimental limitations, such as low-energy cut and low statistics, was also investigated. In the path towards the generalization of these unfolding algorithms to the reconstruction of the runaway electrons 2D velocity-space distribution, the transfer matrices in energy and pitch were calculated for all the hard X-ray diagnostics installed at JET. The weight-function formalism was adopted, which allows studying the sensitivity of the detectors to different energy and pitch regions. The matrices showed a sensitivity peak in the pitch axis which is determined by the angle between the line of sight and the magnetic field. Finally, the gamma camera upgrade installed at the Joint European Torus, with its 10 by 9 lines of sight that observe a poloidal section of the tokamak from two perpendicular projections, allows reconstructing the spatial distribution of fast particles. A tomographic algorithm that makes use of smoothing along the magnetic field lines was implemented. This tomography was first applied to recent three-ion radio frequency heating experiments in D-3He mixed plasmas, during which the gamma camera was able to detect the 16.4 MeV γ-rays from 3He(D,γ)5Li reactions. The spatial distribution of the α-particles born in 3He(D,p)4He reactions was reconstructed and the results were used to validate TRANSP simulations. The tomographic algorithm was also applied to the reconstruction of the runaway electrons spatial profiles during plasma disruptions.
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Lvovskiy, Andrey [Verfasser], Bernhard [Akademischer Betreuer] Unterberg, and Henning [Akademischer Betreuer] Soltwisch. "Development of a multichannel dispersion interferometer for measurements of the plasma density distribution after massive gas injection and during the runaway electron phase in TEXTOR / Andrey Lvovskiy. Gutachter: Bernhard Unterberg ; Henning Soltwisch." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1089006519/34.

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Esarey, Eric Hans. "Stabilization of the tearing mode by turbulent diffusion and runaway electrons." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/14987.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1986.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 208-212.
by Eric Hans Esarey.
Ph.D.
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[Verfasser], Kunaree Wongrach. "Studies of Runaway Electrons during disruptions in the TEXTOR tokamak / Kunaree Wongrach." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2015. http://d-nb.info/1080297774/34.

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Pandya, Santosh. "Development and performance assessment of ITER diagnostics for runaway electrons based on predictive modelling." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0036.

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Dans les tokamaks, Sous l'application champ de électrique, les électrons sont accélérés et en même temps, ils subissent une force de friction due aux collisions avec les autres particules du plasma. Cependant, une fraction de la population totale d'électrons peuvent surmonter la force de friction et atteindre une vitesse proche de la vitesse lumière. Ces électrons relativistes sont découplés du plasma et sont appelés électrons runaway (ER). Ils peuvent apparaître lors des différentes phases d'une décharge de plasma. Par exemple, dans la phase de démarrage ou alors pendant les disruptions, au cours desquelles une fraction importante du courant plasma peut être convertie en ER ayant une énergie pouvant atteindre quelques dizaines de MeV. Les ER créés pendant la phase de perturbation peuvent causer des dommages aux premiers composants murs si un dépôt localisé de forte puissance se produit. ITER étant un tokamak de grande taille et un projet coûteux, la génération d'ER n'est pas souhaitable. La viabilité de la machine nécessite que les ER soient détectés en temps réel. La thèse fournit une étude détaillée dans cette direction pour le développement des deux principaux diagnostics sur ITER impliqués dans les mesures de paramètres pour les ER, à savoir, le moniteur de rayons X durs qui détecte le rayonnement de bremsstrahlung et les caméras visibles et infrarouges qui détectent le rayonnement synchrotron. Une solution de conception unique a été proposée pour le moniteur HXRM et est développée ici et optimisée. Pour les caméras, une modélisation des signaux est effectuée pour la première fois. Pour ce faire, un code de calcul a été développé et validé sur différents tokamaks
In tokamaks, under the application of the electric field, a small fraction of the total electrons population can overcome collisional drag force and attain high velocity close to the speed of light. These relativistic electrons are called Runaway-Electrons (REs). The REs can occur during different phases of a plasma discharge. REs created during the disruptions phase can form a high energetic RE-beam that poses a risk to damage the first wall components if localized high power deposition takes place. ITER being a large size tokamak and an expensive project, generation of REs is not desirable during any phases of a plasma discharge. Detection of these REs and measurements of its parameters are important for the tokamak operation. Hence, RE diagnostics have to be in place to aid the commissioning of the disruption mitigation system and also for the post-event analysis to improve the reliability of RE avoidance. The present thesis gives a detailed study in this direction for the development of the two principal ITER Diagnostics involved in RE parameter measurements, namely the Hard X-Ray Monitor (HXRM) that detects bremsstrahlung radiation and the Visible and Infrared Cameras that detect synchrotron radiation. A unique design solution has been given for the HXRM and is developed, R&D tests were performed and optimized in line with this understanding. For the cameras, it is predicted for the first time which images and signal intensity can be expected. To achieve this, a simple but comprehensive code has been developed and validated on tokamaks that can predict RE parameters and corresponding diagnostic signals which may have further uses also in the context of RE avoidance
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Duchez, Wilfried. "Role of electric field profiles in continuous microwave processing of thermal runaway materials." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-02132009-171150/.

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Forster, Michael [Verfasser], Oswald [Akademischer Betreuer] Willi, Ulrich [Akademischer Betreuer] Samm, and Thomas [Akademischer Betreuer] Klinger. "Runaway electrons in disrupions and perturbed magnetic topologies of Tokamak plasmas / Michael Forster. Gutachter: Oswald Willi ; Ulrich Samm ; Thomas Klinger." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2012. http://d-nb.info/1027368921/34.

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Mohammed, Abdul Haq. "DUAL PURPOSE COOLING PLATES FOR THERMAL MANAGEMENT OF LI-ION BATTERIES DURING NORMAL OPERATION AND THERMAL RUNAWAY." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1518535925672781.

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Books on the topic "Runaway Electron"

1

Entrop, Ingeborg. Confinement of relativistic runaway electrons in tokamak plasmas. Eindhoven: University of Eindhoven, 1999.

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Crutcher, Chris. The Crazy Horse Electric Game. New York: HarperCollins, 2009.

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Crutcher, Chris. The Crazy Horse Electric game. New York: HarperTempest, 2003.

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Crutcher, Chris. The Crazy Horse Electric game. New York: Greenwillow Books, 1987.

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Jennings, Patrick. Faith and the electric dogs. New York: Scholastic, 1996.

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Faith and the electric dogs. New York: Scholastic, 1996.

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Faith and the electric dogs. New York: Scholastic, 1998.

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Riding the runaway horse: The rise and decline of Wang Laboratories. Boston: Little, Brown, 1992.

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Allen, Charlotte Vale. Grace notes. Waterville, Me: Thorndike Press, 2002.

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Allen, Charlotte Vale. Grace notes. Richmond: Mira, 2003.

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Book chapters on the topic "Runaway Electron"

1

Holman, Gordon D. "Acceleration of Runaway Electrons and Joule Heating in Solar Flares." In Unstable Current Systems and Plasma Instabilities in Astrophysics, 191–96. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-6520-1_16.

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Yang, Minglei, Guannan Zhang, Diego del-Castillo-Negrete, Miroslav Stoyanov, and Matthew Beidler. "A Sparse-Grid Probabilistic Scheme for Approximation of the Runaway Probability of Electrons in Fusion Tokamak Simulation." In Lecture Notes in Computational Science and Engineering, 245–64. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-81362-8_11.

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Niemer, K. A., J. G. Gilligan, C. D. Croessmann, and A. C. England. "THEORETICAL ANALYSIS OF A RUNAWAY ELECTRON SUPPRESSION DEVICE." In Fusion Technology 1990, 346–50. Elsevier, 1991. http://dx.doi.org/10.1016/b978-0-444-88508-1.50052-9.

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Bartels, H. W. "RUNAWAY ELECTRONS ON PLASMA FACING COMPONENTS." In Fusion Technology 1992, 181–85. Elsevier, 1993. http://dx.doi.org/10.1016/b978-0-444-89995-8.50027-8.

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Trollope, Anthony. "Chapter 34 the silverbridge election." In The Prime Minister. Oxford University Press, 2011. http://dx.doi.org/10.1093/owc/9780199587193.003.0037.

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About a month after this affair with the runaway horse Arthur Fletcher went to Greshambury, preparatory to his final sojourn at Silverbridge, for the week previous to his election. Greshambury, the seat of Francis Gresham, Esq., who was a great man in...
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BOLT, H., E. ZOLTI, H. CALEN, and A. MORTSELL. "EFFECTS OF RUNAWAY ELECTRONS ENERGY DEPOSITION ON PLASMA FACING COMPONENTS." In Fusion Technology 1990, 406–10. Elsevier, 1991. http://dx.doi.org/10.1016/b978-0-444-88508-1.50064-5.

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Lalinde, Iñaki, Alberto Berrueta, Juan José Valera, Joseba Arza, Pablo Sanchis, and Alfredo Ursúa. "Perspective Chapter: Thermal Runaway in Lithium-Ion Batteries." In Lithium-Ion Batteries - Recent Advanced and Emerging Topics [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106539.

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Lithium-ion batteries (LIBs) are becoming well established as a key component in the integration of renewable energies and in the development of electric vehicles. Nevertheless, they have a narrow safe operating area with regard to the voltage and temperature conditions at which these batteries can work. Outside this area, a series of chemical reactions take place that can lead to component degradation, reduced performance and even self-destruction. The phenomenon consisting of the sudden failure of an LIB, causing an abrupt temperature increase, is known as thermal runaway (TR) and is considered to be the most dangerous event that can occur in LIBs. Therefore, the safety of LIBs is one of the obstacles that this technology must overcome in order to continue to develop and become well established for uses in all types of applications. This chapter presents a detailed study of the general issues surrounding this phenomenon. The origin of the problem is identified, the causes are detailed as well as the phases prior to TR. An analysis is made of the most relevant factors influencing this phenomenon, and details are provided of detection, prevention and mitigation measures that could either prevent the TR or reduce the consequences.
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Conference papers on the topic "Runaway Electron"

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Beloplotov, D. V., V. F. Tarasenko, and D. A. Sorokin. "Influence of a voltage pulse rise time and pressure of air and nitrogen on the parameters of runaway electron beams." In 8th International Congress on Energy Fluxes and Radiation Effects. Crossref, 2022. http://dx.doi.org/10.56761/efre2022.s5-p-000702.

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The generation of runaway electron beams with different high-voltage generators has been studied. The current of runaway electron beams generated during breakdown in air and nitrogen at a pressure range of 25–100 kPa was measured. It has been shown the conditions for electron runaway are easily realized at voltage pulse rise time of up to 200 ns. It has been found that to measure electron beam current at minimum voltages (tens of kilovolts) and a long rise time of the voltage pulse, anodes from a grid with a small cell size should be used. It follows from this work and the results of our previous studies that the generation of a runaway electron initiates the formation of a streamer, the development of which leads to an initial drop in the voltage across the gap.
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Tsap, Yu, A. Stepanov, and Yu Kopylova. "Flare energy release and avalanche ionization of plasma by runaway electrons in lower solar atmosphere." In ASTRONOMY AT THE EPOCH OF MULTIMESSENGER STUDIES. Proceedings of the VAK-2021 conference, Aug 23–28, 2021. Crossref, 2022. http://dx.doi.org/10.51194/vak2021.2022.1.1.133.

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The analysis of the electron acceleration by the quasi-stationary sub-Dreiser electric fields in the lower solar atmospherehas been done. It has been shown that the Dreiser electric field turned out to be several orders of magnitude larger thancoronal values due to the inelastic collisions between electrons and hydrogen atoms. The ionization of hydrogen atoms givesrise to the resulting secondary electrons, which become runaway under the action of sub-Dreiser electric fields. This causesan further avalanche-like ionization of the plasma and leads to the acceleration of the large number of fast electrons up torelativistic energies at small (. 100 km) distances.
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Maltsev, A. N., and S. N. Garagaty. "Dense gas discharge with runaway electrons as electron and ion beam source." In The 33rd IEEE International Conference on Plasma Science, 2006. ICOPS 2006. IEEE Conference Record - Abstracts. IEEE, 2006. http://dx.doi.org/10.1109/plasma.2006.1707012.

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Mamontov, Y., G. Mesyats, K. Sharypov, V. Shpak, S. Shunailov, M. Yalandin, N. Zubarev, and O. Zubareva. "Runaway electrons in an air gap in the presence of a magnetic field." In 8th International Congress on Energy Fluxes and Radiation Effects. Crossref, 2022. http://dx.doi.org/10.56761/efre2022.s5-o-019701.

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The divergence of the runaway electron flow generated in an air-filled discharge gap with a sharp conical cathode can be essentially reduced by applying a guiding axial magnetic field, which opens up prospects for the practical use of formed dense paraxial bunches of fast electrons. In the present work, we consider factors that determine the radial scale of the bunch. Our analysis shows that the main factor is the diffusion of electrons across the magnetic field lines due to collisions with gas molecules. Calculations of the dependence of the runaway electron beam radius on the magnitude of the applied magnetic field, taking this phenomenon into account, agree with the experimental data.
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Panchenko, Alexei N., Mikhail I. Lomaev, Nikolai A. Panchenko, Viktor F. Tarasenko, and Alexei I. Suslov. "Laser action in runaway electron pre-ionized diffuse discharges." In XII International Conference on Atomic and Molecular Pulsed Lasers, edited by Victor F. Tarasenko and Andrey M. Kabanov. SPIE, 2015. http://dx.doi.org/10.1117/12.2218049.

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Apollonov, Victor V., and Vladimir A. Yamschikov. "Runaway electron beams for pumping UV-range gas lasers." In Advanced High-Power Lasers and Applications, edited by Marek Osinski, Howard T. Powell, and Koichi Toyoda. SPIE, 2000. http://dx.doi.org/10.1117/12.380854.

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Starikovskiy, Andrey, Nickolay Aleksandrov, and Mikhail N. Shneider. "Runaway Electron Generation by Decelerating Streamers in Inhomogeneous Atmosphere." In AIAA AVIATION 2021 FORUM. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2021. http://dx.doi.org/10.2514/6.2021-3108.

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Celestin, Sebastien, Bagrat Mailyan, and Ashot Chilingarian. "Modeling the runaway electron distributions in thunderstorm ground enhancements." In 2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS). IEEE, 2014. http://dx.doi.org/10.1109/ursigass.2014.6929894.

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Sharypov, K., E. Osipenko, V. Shpak, S. Shunailov, M. Yalandin, and N. Zubarev. "Parameters of a paraxial magnetized bunch of runaway electrons." In 8th International Congress on Energy Fluxes and Radiation Effects. Crossref, 2022. http://dx.doi.org/10.56761/efre2022.s5-p-031801.

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The methods for diagnosing of a dense paraxial magnetized bunch of run-away electrons (RAEs) in a coaxial air-filled diode with a sharp conical cathode and elongated distance to the anode constriction are described. Spatiotemporal characteristics of the bunch are specified. Investigations tools include luminescence screen and collector-type probe of electron current. The lasts equipped with collimators to measure radial distribution of the current density. Fast response probes confirm that paraxial RAE bunch has the width of about 10 ps, and behind the collimator with diameter of 0.7 mm the current density achieves ≈1 kA/cm2.
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Tsventoukh, Mikhail M. "Runaway electron beam generation and disruption at pulsed gas discharge." In 2015 IEEE International Conference on Plasma Sciences (ICOPS). IEEE, 2015. http://dx.doi.org/10.1109/plasma.2015.7179847.

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Reports on the topic "Runaway Electron"

1

McDevitt, Christopher Joseph, and Xianzhu Tang. Runaway Electron Generation Processes in Tokamak Geometry. Office of Scientific and Technical Information (OSTI), March 2020. http://dx.doi.org/10.2172/1605109.

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Boozer, Allen. Simulation Center for Runaway Electron Avoidance and Mitigation. Final report. Office of Scientific and Technical Information (OSTI), December 2018. http://dx.doi.org/10.2172/1487244.

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Hollmann, Eric. A laser inverse compton scattering diagnostic to study runaway electron dynamics during tokamak disruptions. Office of Scientific and Technical Information (OSTI), November 2021. http://dx.doi.org/10.2172/1829731.

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Evans, Todd. A LASER INVERSE COMPTON SCATTERING DIAGNOSTIC TO STUDY RUNAWAY ELECTRON DYNAMICS DURING TOKAMAK DISRUPTIONS. Office of Scientific and Technical Information (OSTI), December 2021. http://dx.doi.org/10.2172/1837231.

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Holland, Christopher, and Charlson C. Kim. Simulation Center for Runaway Electron Avoidance and Mitigation (SCREAM) - NIMROD DIII-D Shattered Pellet Injection Disruption Mitigation and RE Modeling. Final report. Office of Scientific and Technical Information (OSTI), September 2019. http://dx.doi.org/10.2172/1560382.

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Xiaoyin Guan, Hong Qin, and Nathaniel J. Fisch. Phase-space Dynamics of Runaway Electrons In Tokamaks. Office of Scientific and Technical Information (OSTI), August 2010. http://dx.doi.org/10.2172/988884.

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None, None. Hyper-Velocity Nanoparticle Plasma Jet as Fast Probe for Runaway Electrons in Tokamak Disruptions. Office of Scientific and Technical Information (OSTI), March 2019. http://dx.doi.org/10.2172/1503918.

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Freiberg, Beatrice, and William Dickens. The Impact of the Runaway Office on Union Certification Elections in Clerical Units. Cambridge, MA: National Bureau of Economic Research, August 1985. http://dx.doi.org/10.3386/w1693.

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