Journal articles: 'Cryogenics; Laser cooling'

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Lisiecki, A., D. Ślizak, and A. Kukofka. "Laser cladding of Co-based metallic powder at cryogenic conditions." Journal of Achievements in Materials and Manufacturing Engineering 1, no. 95 (July 2, 2019): 20–31. http://dx.doi.org/10.5604/01.3001.0013.7622.

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Purpose: of this paper was demonstration a novel technique of laser cladding by experimentally composed Co-based metallic powder and forced cooling of the substrate by liquid nitrogen under cryogenic conditions, at the temperature -190°C, for producing clad layers with enhanced microstructure characteristic and properties. Design/methodology/approach: Technological tests of laser cladding were conducted by means of a high power fibre laser HPFL with maximum output power 3.0 kW, and six-axis robot. The experimental Co-based powder was composed for providing high abrasive wear resistance, high resistance for impact load, and also for corrosion resistance at elevated temperature. The unique and novel technique of forced cooling of the substrate was provided by immersing the specimens in the liquid nitrogen bath. The three coaxial nozzle head was designed and custom made to provide precise deposition of the powder delivered into the laser beam irradiation region. The scope of the study included tests of conventional laser cladding at free cooling in ambient air in a wide range of processing parameters, and also trials of laser cladding under cryogenic conditions. The test clad layers produced by conventional laser cladding and by the novel technique of laser powder deposition under cryogenic conditions were investigated and compared. Findings: The obtained results indicate that the novel technique of forced cooling the substrate by liquid nitrogen bath provides lower penetration depth, as well as low dilution of the clad, and also provides higher hardness of the clads. Additionally, it is possible shaping the geometry of the individual bead, providing high reinforcement and low width. Research limitations/implications: The presented results are based just on preliminary test of the novel technique of laser cladding under cryogenic conditions. Therefore, further study and detailed analyse of the influence of the cooling rate on the quality, microstructure, and properties of the deposited coatings are required. Practical implications: The study is focused on practical application of the novel technique for manufacturing of wear resistance coatings characterised with enhanced performance compared to conventional range of application of the laser cladding. Originality/value: Novel technique of laser cladding at forced cooling under cryogenic conditions was demonstrated. The powder used for cladding trials was experimentally composed (not commercially available). The experimental stand custom made was used with custom made powder feeding rate, and also with custom made coaxial nozzle head.

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Lisiecki, Aleksander, and Dawid Ślizak. "Hybrid Laser Deposition of Fe-Based Metallic Powder under Cryogenic Conditions." Metals 10, no. 2 (January 28, 2020): 190. http://dx.doi.org/10.3390/met10020190.

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The purpose of this study was to demonstrate the novel technique of laser deposition of Fe-based powder under cryogenic conditions provided by a liquid nitrogen bath. Comparative clad layers were produced by conventional laser cladding at free cooling conditions in ambient air and by the developed process combining laser cladding and laser gas nitriding (hybrid) under cryogenic conditions. The influence of process parameters and cooling conditions on the geometry, microstructure, and hardness profiles of the clad layers was determined. The optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), and XRD test methods were used to determine the microstructure and phase composition. The results indicate that the proposed technique of forced cooling the substrate in a nitrogen bath during the laser deposition of Fe-based powder is advantageous because it provides favorable geometry of the clad, low dilution, a narrow heat-affected zone, a high hardness and uniform profile on the cross-sections, homogeneity, and refinement of the microstructure. The influence of the forced cooling on microstructure refinement was quantitatively determined by measuring the secondary dendrite arm spacing (SDAS). Additionally, highly dispersed nanometric-sized (200–360 nm) precipitations of complex carbides were identified in interdendritic regions.

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Chvykov, Vladimir. "Ti:Sa Crystals in Ultra-High Peak and Average Power Laser Systems." Crystals 11, no. 7 (July 20, 2021): 841. http://dx.doi.org/10.3390/cryst11070841.

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In this paper, Ti:Sa amplifiers with crystals of the different geometries are discussed. Benefits of using this active medium for a thin disk (TD) and slab amplifiers are evaluated numerically and tested experimentally. Thermal management for amplifiers with multi-kW average power and multi-J pulse energy has been demonstrated. The presented numerical simulations revealed the existing limitations for heat extraction in TD geometry in the sub-joule energy regime for higher repetition rate operation. Geometry conversion from TD to thin-slab (TS) and cross-thin-slab (XTS) configurations significantly increases the cooling efficiency with an acceptable crystal temperature for pump average power values up to few kW with room temperature cooling, and up to tens of kW with cryogenic cooling. The abilities to attain 0.3 J output energy and a greater than 50% extraction efficiency were demonstrated with a repetition rate exceeding 10 kHz with room temperature cooling and one order more of a repetition rate with cryogenic conditions with pulsed pumping. Direct diode pumping simulated for CW regimes demonstrated 1.4 kW output power with 34% extraction efficiency using room temperature cooling and more than 10 kW and ~40% efficiency with cryogenic cooling.

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Seletskiy, Denis V., Seth D. Melgaard, Stefano Bigotta, Alberto Di Lieto, Mauro Tonelli, and Mansoor Sheik-Bahae. "Laser cooling of solids to cryogenic temperatures." Nature Photonics 4, no. 3 (January 17, 2010): 161–64. http://dx.doi.org/10.1038/nphoton.2009.269.

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Perin, J. P., F. Millet, M. Divoky, and B. Rus. "Cryogenic cooling for high power laser amplifiers." EPJ Web of Conferences 59 (2013): 08005. http://dx.doi.org/10.1051/epjconf/20135908005.

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Lisiecki, Aleksander, and Dawid Ślizak. "Hybrid Laser Deposition of Composite WC-Ni Layers with Forced Local Cryogenic Cooling." Materials 14, no. 15 (August 2, 2021): 4312. http://dx.doi.org/10.3390/ma14154312.

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The purpose of this study was to demonstrate the effect of forced and localized cooling by nitrogen vapours stream under cryogenic conditions during laser deposition of WC-Ni powder on the geometry, microstructure of clad layers and dry sliding wear resistance of the coatings. For this purpose, comparative tests were performed by conventional laser cladding at free cooling conditions in ambient air and by the developed novel process of laser deposition with additional localized cooling of the solidifying deposit by nitrogen vapours stream. Due to presence of gaseous nitrogen in the region of the melt pool and solidifying deposit, the process was considered as combining laser cladding and laser gas nitriding (performed simultaneously), thus the hybrid process. The influence of the heat input and cooling conditions on the geometrical features, dilution rate, share of carbides relative to the matrix, and the fraction share of carbides, as well as hardness profiles on cross sections of single stringer beads was analysed and presented. The XRD, EDS analysis and the sieve test of the experimental powder were used to characterize the composite WC-Ni type powder. The OM, SEM, EDS and XRD test methods were used to study the microstructure, chemical and phase composition of clad layers. Additionally, ball-on-disc tests were performed to determine the wear resistance of representative coatings under dry sliding conditions. The results indicate that the novel demonstrated technique of localized forced cooling of the solidifying deposit has advantageous effect, because it provides approximately 20% lower penetration depth and dilution, decreases tendency for tungsten carbides decomposition, provides more uniform distribution and higher share of massive eutectic W2C-WC carbides across the coating. While the conventionally laser cladded layers show tendency for decomposition of carbide particles and resolidifying dendritic complex carbides mainly M2C, M3C and M7C3 containing iron, nickel, and tungsten, and with Ni/Ni3B matrix. The quantitative relationship between heat input, cooling conditions and the carbides grain size distribution as well as carbides share in relation to the matrix was determined.

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Heep, Thomas, Christian Bickert, and Eberhard Abele. "Application of Carbon Dioxide Snow in Machining of CGI using an Additively Manufactured Turning Tool." Journal of Manufacturing and Materials Processing 3, no. 1 (January 23, 2019): 15. http://dx.doi.org/10.3390/jmmp3010015.

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The application of conventional cooling lubricants for the tribological conditioning of machining processes involves high additional costs and health risks. The application of a cryogenic carbon dioxide (CO2) snow cooling strategy is an economical and environmentally sound alternative for oily cooling emulsions since it has a high cooling effect as well as a residue-free sublimation. This article introduces a laser additive manufactured tool holder with an integrated dual nozzle which enables CO2-snow jet application. Initially this work focuses on the characterization and the selection of a suitable nozzle geometry. The modular tool body features an adapted channel structure for process-reliable and targeted CO2-snow cooling for turning processes. This enables the simultaneous cooling of the rake and flank face with CO2-snow, as well as the application of cryogenic multi-component cooling of the rake face. In the context of this study, the focus lies on the technological evaluation of three different supply strategies during the continuous turning of compacted graphite iron CGI-450 at increased cutting speed. It was established that an efficient rake face cooling is indispensable to achieve a low thermal tool load, and thus lower crater wear behavior. Therefore, this study contributes to an improvement in cryogenic machining processes regarding the design of additively manufactured tool bodies for process-reliable CO2-snow cooling, as well as for the selection of supply strategies to minimize the thermomechanical tool load.

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Rybakov, A. S., E. I. Demikhov, E. A. Kostrov, V. S. Litvin, N. M. Sobolevsky, L. N. Latysheva, and N. G. Borisenko. "Cryogenic setup for MJ class laser targets." Laser and Particle Beams 37, no. 01 (March 2019): 25–29. http://dx.doi.org/10.1017/s0263034619000077.

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AbstractThe cryogenic system for maintaining a target at a constant temperature in the range 5–25 K after shutting off the pulse tube (PT) cryogenic refrigerator is developed and tested. The temperature stability at the sample is ±2 mK for at least 20 hours. The cryogenic setup consists of cryostat, PT cryocooler, liquid helium vessel, helium gas supply, thermo-radiation shield, thermal resistance. The system provides 0.25 W of cooling power at the target. The appropriate thermal resistance should be used for different temperatures. The designed operation mode is 3 minutes off and 15 minutes on. The deactivation of PT cryocooler allows to achieve the target position stability of 1 micrometer or less during the X-ray characterization. The effect of neutron-shield was estimated using Monte-Carlo simulation.

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Demirorer, Mete, Wojciech Suder, Supriyo Ganguly, Simon Hogg, and Hassam Naeem. "Development of laser welding of high strength aluminium alloy 2024-T4 with controlled thermal cycle." MATEC Web of Conferences 326 (2020): 08005. http://dx.doi.org/10.1051/matecconf/202032608005.

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An innovative process design, to avoid thermal degradation during autogenous fusion welding of high strength AA 2024-T4 alloy, based on laser beam welding, is being developed. A series of instrumented laser welds in 2 mm thick AA 2024-T4 alloys were made with different processing conditions resulting in different thermal profiles and cooling rates. The welds were examined under SEM, TEM and LOM, and subjected to micro-hardness examination. This allowed us to understand the influence of cooling rate, peak temperature, and thermal cycle on the growth of precipitates, and related degradation in the weld and heat affected area, evident as softening. Although laser beam welding allows significant reduction of heat input, and higher cooling rates, as compared to other high heat input welding processes, this was found insufficient to completely supress coarsening of precipitate in HAZ. To understand the required range of thermal cycles, additional dilatometry tests were carried out using the same base material to understand the time-temperature relationship of precipitate formation. The results were used to design a novel laser welding process with enhanced cooling, such as with copper backing bar and cryogenic cooling.

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Lizzul, Lucia, Rachele Bertolini, Andrea Ghiotti, and Stefania Bruschi. "Turning of Additively Manufactured Ti6Al4V: Effect of the Highly Oriented Microstructure on the Surface Integrity." Materials 14, no. 11 (May 26, 2021): 2842. http://dx.doi.org/10.3390/ma14112842.

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Additive manufacturing processes induce a high orientation in the microstructure of the printed part due to the strong thermal gradients developed during the process caused by the highly concentrated heat source that is used to melt the metal powder layer-by-layer. The resulting microstructural anisotropy may have an effect on the post-processing operations such as machining ones. This paper investigates the influence of the anisotropy in turning operations carried out on laser powder bed fused Ti6Al4V parts manufactured with different scanning strategies. The machinability under both transverse and cylindrical turning operations was assessed in terms of surface integrity, considering both surface and sub-surface aspects. The effect of the different cooling conditions, that is flood and cryogenic ones, was studied as well. The outcomes showed that the microstructural anisotropy had a remarkable effect on the machining operations and that the cryogenic cooling enhanced the effect of the anisotropy in determining the surface integrity.

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Heeg, B., G. Rumbles, M. D. Stone, A. Khizhnyak, and P. A. Debarber. "Feasibility evaluation of intracavity solid state laser cooling to cryogenic temperatures." Journal of Modern Optics 53, no. 8 (May 20, 2006): 1109–20. http://dx.doi.org/10.1080/09500340500499674.

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Tokita, S., J. Kawanaka, M. Fujita, T. Kawashima, and Y. Izawa. "Sapphire-conductive end-cooling of high power cryogenic Yb:YAG lasers." Applied Physics B 80, no. 6 (March 17, 2005): 635–38. http://dx.doi.org/10.1007/s00340-005-1779-4.

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Куницына, Е. В., М. А. Ройз, И. А. Андреев, Е. А. Гребенщикова, А. А. Пивоварова, M. Ahmetoglu (Afrailov), Е. В. Лебедок, Р. Ю. Микулич, Н. Д. Ильинская, and Ю. П. Яковлев. "Фотодиоды для регистрации излучения квантово-размерных дисковых лазеров, работающих на модах шепчущей галереи (2.2-2.3 мкм)." Физика и техника полупроводников 54, no. 7 (2020): 677. http://dx.doi.org/10.21883/ftp.2020.07.49515.9378.

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Photodiodes developed in the GaSb-InAs system were first used for investigation the spectral characteristics of single and coupled disk lasers emitting on whispering gallery modes at 2.2–2.3 µm. The capacity of the photodiodes with a diameter of photosensitive area of 2.0 mm was C=520 pF at U=−2 V, which corresponds to a time constant of tau=53 ns. It is shown that the parameters of the developed photodiodes make it possible to detect the emission of quantum-sized disk lasers at room temperature and not to use cryogenic cooling.

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Elokhin, V. A., A. N. Krutchinsky, and S. E. Ryabov. "Vibrational cooling of aniline molecules by laser evaporation from a cryogenic matrix." Chemical Physics Letters 170, no. 2-3 (July 1990): 193–96. http://dx.doi.org/10.1016/0009-2614(90)87114-7.

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NUNDY, UTPAL. "Benefits of cryogenic cooling on the operation of a pulsed CO2 laser." Pramana 82, no. 1 (January 2014): 147–52. http://dx.doi.org/10.1007/s12043-013-0654-9.

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Tokita, S., J. Kawanaka, M. Fujita, T. Kawashima, and Y. Izawa. "Sapphire-Conductive End-Cooling of High Power Cryogenic Yb: YAG Lasers." Review of Laser Engineering 36, Supplement (2008): 31–35. http://dx.doi.org/10.2184/lsj.36.31.

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17

Hori, Masaki. "Precision laser spectroscopy experiments on antiprotonic helium." EPJ Web of Conferences 181 (2018): 01001. http://dx.doi.org/10.1051/epjconf/201818101001.

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At CERN‘s Antiproton Decelerator (AD) facility, the Atomic Spectroscopyand Collisions Using Slow Antiprotons (ASACUSA) collaboration is carrying out precise laser spectroscopy experiments on antiprotonic helium (p̅He+ ≡ p̅+He2++e−) atoms. By employing buffer-gas cooling techniquesin a cryogenic gas target, samples of atoms were cooled to temperatureT = 1.5–1.7 K, thereby reducing the Doppler width in the single-photon resonance lines. By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as Mp̅/me = 1836.1526734(15). This agreed with the known proton-to-electron mass ratio with a precision of 8 . 1010. Further improvements in the experimental precision are currently being attempted. The high-quality antiproton beam provided by the future Extra Low Energy Antiproton Ring (ELENA) facility should further increase the experimental precision.

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Kuvshinskii, Mickail, Sergei Oreshkin, Sergei Popov, Valentin Rudenko, Ivan Yudin, Valentina Azarova, and Sergei Blagov. "Tests of Cryogenic Fabry–Perot Cavity with Mirrors on Different Substrates." Applied Sciences 9, no. 2 (January 10, 2019): 230. http://dx.doi.org/10.3390/app9020230.

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Experiments were performed with Fabry–Perot optical resonators in vacuum at low temperatures. Mirrors were applied on substrates of various optical materials. An infrared laser with a wavelength of 1.064 microns was used. The pump power at the maximum could reach 450 mW. The evolution of the optical properties of the FP cavity was traced in the temperature range 300–10 K. The main parameters measured were the integral characteristics of the FP resonances–sharpness (finesse) and contrast of interference. Three types of substrates were tested: a sitall, an optical glass with ultra low thermal expansion (ULE); sapphire; and calcium fluoride. During cooling, the degradation of the integral characteristics of the FP cavity was observed for the sitall mirrors due to the loss of the properties of ULE, and for sapphire mirrors due to the birefringence effect. The satisfactory constancy of the integral characteristics of the FP resonator on calcium fluoride was demonstrated in the entire temperature range studied.

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Semenov, K. O. "On the process of cooling of a laser target with formation of a cryogenic fuel layer in it." Nanostuctures. Mathematical Physics and Modelling 17, no. 2 (2017): 74–84. http://dx.doi.org/10.31145/2224-8412-2017-17-2-74-84.

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Chapman, Henry N. "X-Ray Free-Electron Lasers for the Structure and Dynamics of Macromolecules." Annual Review of Biochemistry 88, no. 1 (June 20, 2019): 35–58. http://dx.doi.org/10.1146/annurev-biochem-013118-110744.

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X-ray free-electron lasers provide femtosecond-duration pulses of hard X-rays with a peak brightness approximately one billion times greater than is available at synchrotron radiation facilities. One motivation for the development of such X-ray sources was the proposal to obtain structures of macromolecules, macromolecular complexes, and virus particles, without the need for crystallization, through diffraction measurements of single noncrystalline objects. Initial explorations of this idea and of outrunning radiation damage with femtosecond pulses led to the development of serial crystallography and the ability to obtain high-resolution structures of small crystals without the need for cryogenic cooling. This technique allows the understanding of conformational dynamics and enzymatics and the resolution of intermediate states in reactions over timescales of 100 fs to minutes. The promise of more photons per atom recorded in a diffraction pattern than electrons per atom contributing to an electron micrograph may enable diffraction measurements of single molecules, although challenges remain.

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López-Jaramillo, F. J., J. M. García-Ruiz, J. A. Gavira, and F. Otálora. "Crystallization and cryocrystallography inside X-ray capillaries." Journal of Applied Crystallography 34, no. 3 (May 22, 2001): 365–70. http://dx.doi.org/10.1107/s0021889801003697.

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This paper presents a modification of the gel acupuncture method to grow isolated crystals inside X-ray capillaries. Protein crystals are grown from 2–12 µl of gelled agarose–protein solution, cryoprotected and immobilized by the gel matrix. The same X-ray capillary that acts as a crystallization reactor is used to transport the crystals to the X-ray source and to collect data at both room temperature and 100 K, without any post-crystallization manipulation. To enhance the flash-cooling stage, two additional elements are proposed for inclusion in the cryosystems currently in use: a laser pointer to illuminate the crystal to be flash-cooled and a trap to divert the N2flow and switch from room temperature to 100 K without misalignment of the crystal. With the proposed implementation, data can be collected at different temperatures from the same crystal in exactly the same orientation. This permits the study, at lattice level, of changes in unit-cell parameters, mosaic spread and crystal quality induced by cryogenic temperatures and annealing techniques.

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Singh, Rupesh, Koushik Das, Junnosuke Okajima, Shigenao Maruyama, and Subhash C. Mishra. "Modeling skin cooling using optical windows and cryogens during laser induced hyperthermia in a multilayer vascularized tissue." Applied Thermal Engineering 89 (October 2015): 28–35. http://dx.doi.org/10.1016/j.applthermaleng.2015.06.006.

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Baloglu, Eyup Can, Tuba Okutucu Ozyurt, and Zafer Dursunkaya. "Investigation of Warpage Behavior of Silicon Semiconductor on a Silicon - Adhesive - Ceramic Integrated Structure at Cryogenic Temperatures--STUDENT BEST PAPER $1500." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2016, DPC (January 1, 2016): 001751–72. http://dx.doi.org/10.4071/2016dpc-wp45.

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Silicon wafer is widely used as a base material for readout integrated circuit (ROIC) of infrared sensors. There is a heterogeneous component assembly with the silicon wafer material. Warpage behavior of silicon readout integrated circuit is dependent on the material properties and geometrical properties of the integrated materials. Warpage behavior of the silicon material directly affects the warpage of the sensor which must be operated at cryogenic temperatures (around 80 K). There exist a great difference between the operation and storage temperatures (~ 300 K) of these devices. When different materials with different thermal expansion coefficients are used such devices, thermal stresses develop on the components and surface deformations named as “warpage” are observed on the materials. The measurement of excessive thermal stress or warpage formation on the sensor is vital for reliability issues. In this study, warpage behavior of silicon material is examined in the temperature range from room temperature down to cryogenic temperatures (80 K) and under vacuum conditions less than 1 mTorr. The silicon ROIC is integrated on an alumina ceramic by applying an adhesive between these two layers. After the application of the adhesive material, the integration of the silicon to ceramic is accomplished using a pick and place equipment. The warpage of silicon wafer is measured by a Fizeau Laser Interferometer which uses a 633 nanometer wavelength He – Ne laser. The warpage of the diced silicon is measured before and after the integration to the ceramic so that the effect of curing process of the adhesive is determined after which, the warpage of the silicon material is measured at atmospheric pressure and also under vacuum conditions at room temperature. The warpage of silicon material on the integrated structure is measured with increments of 10 K for both cooling from room temperature to 80 K and heating from 80 K to room temperature. In order to reach cryogenic temperatures, a liquid nitrogen cooled vacuum envelope is utilized. The envelope has an optical flat (made of BK7 material and 2.35 mm thick) for interferometric measurements. There are a total of five integrated structures for the warpage measurements. At each of these structures, the silicon material thickness is different. Comparison of the warpage behavior of the silicon material for different thicknesses are performed. Thermal cycling between room temperature and 80 K is also performed up to 5 cycles for each of the integrated structures. Thermal cycling effect on silicon warpage is discussed for silicon - alumina - adhesive trimaterial assembly structure.

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Griffin, Brendon. "Cryogenic cooling and in situ analysis of fluid inclusions in geological materials with an ultra-thin windowed Si(Li) detector in a SEM." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 207. http://dx.doi.org/10.1017/s0424820100134636.

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The determination of fluid compositions in geological processes is an essential but difficult problem. Many techniques have been developed based on the optical microscope. These are indirect analytical techniques, determining fluid composition by analogy. More sophisticated spectroscopic techniques, e.g. laser microprobes, are relatively inaccessible through high capital cost. Scanning electron microscopes [SEM’s] and electron microprobes have been used to identify the non-volatile components by decrepitating near-surface inclusions with an energetic electron beam and then analysing the residual.It is found that application of the cryo-SEM to the study of fluid inclusions with the common availability of windowless and low absorbance windowed Si(Li) detectors is a convenient and low cost technique. Suitable slabs (<1 mm) are frozen and then fractured. No coating is applied, to minimise element interference. The fresh surfaces are inspected using backscattered electron [BSE] imaging and exposed inclusions analysed.Studies of inclusions in quartz, fluorite and sphalerite have determined the presence of carbon dioxide, water and various daughter salts, including halite (NaCl) and hydrophilite (CaCl2).

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Goodman, William A. "3D Printed and Additively Manufactured RoboSiC™ for Space, Cryogenic, Laser and Nuclear Environments." International Symposium on Microelectronics 2018, no. 1 (October 1, 2018): 000099–103. http://dx.doi.org/10.4071/2380-4505-2018.1.000099.

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Abstract Goodman Technologies has been directly responsive to, and focused on, 3D printing and additive manufacturing techniques, and what it takes to manufacture in zero-gravity. During a NASA Phase I SBIR project, using a small multi-printhead machine, we showed that it was possible to formulate and 3D print silicon carbide into shapes appropriate for lightweight mirrors and structures at the production rate of 1.2 square-meter/day. Gradient lattice coupons with feature sizes on the order of 0.8mm were printed and were easily machined to very fine tolerances, ten-thousandths of an inch by Coastline Optics in Camarillo, CA. To further elaborate on the list of achievements, in Phase I, Team GT demonstrated three different ceramization techniques for 3D printing low areal cost, ultra-lightweight Silicon Carbide (SiC) mirrors and structures, radiation shielding, and electronics, several of which could be employed in microgravity The Goodman Technologies briefing presented at 2017 Mirror Technology Days “3D Printed Silicon Carbide Scalable to Meter-Class Segments for Far-Infrared Surveyor: NASA Contract NNX17CM29P along with sample coupons resulted in extreme interest from both Government and the Contractor communities. Our materials, which we call RoboSiC™, is suited for many other applications including heat sinks and radiation shielding for space electronics, and we have already started to make the first parts for these applications. The successful Phase I project suggests that we will meet or exceed all NASA requirements for the primary mirror of a Far-IR Surveyor such as the Origins Space Telescope (OST) and have a high probability solution for the LUVOIR Surveyor in time for the 2020 Decadal Survey. Results indicate that printing on the ground will achieve an areal density of 7.75 kg/square-meter (~39% of a James Webb Space Telescope (JWST) beryllium segment), a cost to print of $60K/segment, and an optical surface that has nanometer-scale tolerances. Printing in the microgravity environment of space we have the potential to achieve an areal density of 1.0–2.0 kg/square meter (<10% of a JWST beryllium segment), with a cost to print of ~$10K/segment. The areal density is 2–15 times better than the NASA goal of 15 kg/square meter, and the costs are substantially better than the NASA goal of $100K/square meter. The encapsulated gradient lattice construction provides a uniform CTE throughout the part for dimensional stability, incredible specific stiffness, and the added benefit of cryo-damping. For the extreme wavefront control required by the Large UV/Optical/IR Surveyor (LUVOIR) the regularly spaced lattice construction should also provide deterministic mapping of any optical distortions directly to the regular actuator spacing of a deformable mirror (DM). Some of our processes will also allow for direct embedding of electronics for active structures and segments. Encapsulation of the lattice structures will allow for actively cooling with helium for unprecedented low emissivity and thermal control. Several decades of experience and testing with SiC have shown that our materials will survive, nay thrive in, the most extreme Space, Cryogenic, Laser and Nuclear Environments.

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Marciniak, A., C. Joblin, G. Mulas, V. Rao Mundlapati, and A. Bonnamy. "Photodissociation of aliphatic PAH derivatives under relevant astrophysical conditions." Astronomy & Astrophysics 652 (August 2021): A42. http://dx.doi.org/10.1051/0004-6361/202140737.

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Context. The interaction of polycyclic aromatic hydrocarbons (PAHs) with vacuum ultraviolet (VUV) photons triggers the emission of the well-known aromatic infrared bands (AIBs), but other mechanisms, such as fragmentation, can be involved in this interaction. Fragmentation leads to selection effects that favor specific sizes and structures. Aims. Our aim is to investigate the impact of aliphatic bonds on the VUV photostability of PAH cations in a cryogenic and collisionless environment with conditions applicable for photodissociation regions (PDRs). Methods. The studied species are derived from pyrene (C16H10) and coronene (C24H12) and contain aliphatic bonds either in the form of methyl or ethyl sidegroups or of superhydrogenation. Their cations are produced by laser desorption ionization and isolated in the cryogenic ion cell of the PIRENEA setup, where they are submitted to VUV photons of 10.5 eV energy over long timescales (~1000 s). The parent and fragment ions are mass-analyzed and their relative intensities are recorded as a function of the irradiation time. The fragmentation cascades are analyzed with a simple kinetics model from which we identify fragmentation pathways and derive fragmentation rates and branching ratios for both the parents and their main fragments. Results. Aliphatic PAH derivatives are found to have a higher fragmentation rate and a higher carbon to hydrogen loss compared to regular PAHs. On the other hand, the fragmentation of PAHs with alkylated sidegroups forms species with peripheral pentagonal cycles, which can be as stable as, or even more stable than, the bare PAH cations. This stability is quantified for the main ions involved in the fragmentation cascades by the comparison of the fragmentation rates with the photoabsorption rates derived from theoretical photoabsorption cross sections. The most stable species for which there is an effective competition of fragmentation with isomerization and radiative cooling are identified, providing clues on the structures favored in PDRs. Conclusions. This work supports a scenario in which the evaporation of nanograins with a mixed aliphatic and aromatic composition followed by VUV photoprocessing results in both the production of the carriers of the 3.4 μm AIB by methyl sidegroups and in an abundant source of small hydrocarbons at the border of PDRs. An additional side effect is the efficient formation of stable PAHs that contain some peripheral pentagonal rings. Our experiments also support the role of isomerization processes in PAH photofragmentation, including the H-migration process, which could lead to an additional contribution to the 3.4 μm AIB.

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Calendron, Anne-Laure, Joachim Meier, Michael Hemmer, Luis E. Zapata, Fabian Reichert, Huseyin Cankaya, Damian N. Schimpf, et al. "Laser system design for table-top X-ray light source." High Power Laser Science and Engineering 6 (2018). http://dx.doi.org/10.1017/hpl.2018.5.

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We present possible conceptual designs of a laser system for driving table-top free-electron lasers based on terahertz acceleration. After discussing the achievable performances of laser amplifiers with Yb:YAG at cryogenic and room temperature and Yb:YLF at cryogenic temperature, we present amplification modules with available results and concepts of amplifier chains based on these laser media. Their performances are discussed in light of the specifications for the tasks within the table-top light source. Technical and engineering challenges, such as cooling, control, synchronization and diagnostics, are outlined. Three concepts for the laser layout feeding the accelerator are eventually derived and presented.

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Le Garrec, Bruno. "Challenges of high power diode-pumped lasers for fusion energy." High Power Laser Science and Engineering 2 (August 1, 2014). http://dx.doi.org/10.1017/hpl.2014.33.

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Abstract This paper reviews the different challenges that are encountered in the delivery of high power lasers as drivers for fusion energy. We will focus on diode-pumped solid-state lasers and we will highlight some of the main recent achievements when using ytterbium, cryogenic cooling and ceramic gain media. Apart from some existing fusion facilities and some military applications of diode-pumped solid-state lasers, we will show that diode-pumped solid-state lasers are scalable to inertial fusion energy (IFE)’s facility level and that the all-fiber laser scheme is very promising.

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29

Bellec, Morgane, Alain Girard, Guillaume Balarac, Ulrich Bieder, François Millet, and Nicolas Luchier. "Effect of Turbulence on the Wavefront of an Ultrahigh Intensity Laser Beam." Journal of Fluids Engineering 143, no. 3 (December 11, 2020). http://dx.doi.org/10.1115/1.4049113.

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Abstract Ultrahigh intensity lasers face thermal management issues that limit their repetition rates. The key challenge is to efficiently evacuate the heat deposited in the amplifier by the optical pumping without impacting the output laser beam quality. The amplifier can have a multislab geometry where the laser beam crosses successive amplifying slabs and the cooling channels that separate them. This work investigates numerically how a cryogenic cooling of the amplifier by turbulent channel flows may affect the wavefront of the laser beam. To this end, large eddy simulations (LESs) representative of the amplifier cooling are performed using TrioCFD, a code developed by the CEA. First, validation simulations are carried out for heated channel flows, allowing comparisons to direct numerical simulation (DNS) results from the literature. Then, LESs of an open turbulent channel flow cooling two slabs are conducted using conjugated heat transfer between the solid and the fluid. The phase distortions, mean and fluctuations, induced by the inhomogeneous and turbulent temperature field are computed directly from the LES. A moderate although non-negligible effect of the turbulence on the laser wavefront was found. This optical effect increases when the slab heating increases. A comparison to the Sutton model, widely used in aero-optic studies, was performed, and its applicability was found limited for this problem. For the first time, TrioCFD is used to address the question of the beam impact of the cooling of laser amplifiers, and it has proven to be a valuable tool for such application.

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30

Zhao, Yi, and Xin Zhang. "Investigation upon Mechanical Properties of Thin Film Silicon Under Cryogenic Temperature." MRS Proceedings 851 (2004). http://dx.doi.org/10.1557/proc-851-nn5.6.

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ABSTRACTThin film silicon material has an extensive application in cooling satellite instrumentation under cryogenic environment. The performance and reliability of the cooling system heavily depends on mechanical behavior of the thin films. In this paper, we built an experimental setup and used compressive gas to actuate a silicon thin film under both room temperature and cryogenic temperature. The elastic modulus was derived from the film's deflection using laser Michelson interferometer. Stress distribution was obtained using Micro Raman spectroscopy. It was found that Young's modulus derived from the deflection increases with decreasing temperature. Compressive stress concentrated at edge centers of the film and tensile stress occurred at the center. There is a good match between the theoretical predications and experimental observations.

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31

Lucianetti, Antonio, Magdalena Sawicka, Ondrej Slezak, Martin Divoky, Jan Pilar, Venkatesan Jambunathan, Stefano Bonora, Roman Antipenkov, and Tomas Mocek. "Design of a kJ-class HiLASE laser as a driver for inertial fusion energy." High Power Laser Science and Engineering 2 (May 1, 2014). http://dx.doi.org/10.1017/hpl.2014.15.

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Abstract We present the results of performance modeling of a diode-pumped solid-state HiLASE laser designed for use in inertial fusion energy power plants. The main amplifier concept is based on a He-gas-cooled multi-slab architecture similar to that employed in Mercury laser system. Our modeling quantifies the reduction of thermally induced phase aberrations and average depolarization in ${\mathrm{Yb}}^{{3+}}$ :YAG slabs by a combination of helium cryogenic cooling and properly designed (doping/width) cladding materials.

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McCann, Patrick J., and Yurii Selivanov. "IV-VI Semiconductor Mid-IR Lasers." MRS Proceedings 891 (2005). http://dx.doi.org/10.1557/proc-0891-ee01-05.

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ABSTRACTMid-IR lasers fabricated from narrow bandgap IV-VI semiconductors are proven devices for molecular spectroscopy applications. Wide single-mode tunability, low waste heat generation, and large spectral coverage from about 1000 cm−1 (10 µm) to about 2500 cm−1 (4 µm) have allowed development of laser absorption spectroscopy instrumentation for fast and sensitive measurement of specific gas phase molecules. For example, IV-VI mid-IR lasers with emission in the 5.2 µm spectral range have recently enabled the development of breath analysis instruments for real-time measurement of exhaled nitric oxide (eNO). Laser tunability with current ramping is sufficient for simultaneous measurement of exhaled carbon dioxide (eCO2), a capability that allows highly accurate determination of eNO concentrations in the low ppb range, a sensitivity required for assessing airway inflammation in patients with asthma. After discussing emerging medical diagnostic applications this paper reviews recent progress in the development of liquid-nitrogen-free cryogenic cooling systems for IV-VI mid-IR lasers. A description of continuing research on the development of improved IV-VI lasers, where the primary objective is to fabricate devices with continuous wave (cw) operation at room temperature is then presented. Theoretical and experimental analysis of (111)-oriented multiple quantum well (MQW) IV-VI materials show that it should be possible to reduce lasing thresholds significantly. In addition, results from transferring IV-VI materials from low thermal conductivity growth substrates to higher thermal conductivity copper show that new laser packaging methods can significantly improve active region heat dissipation. Together, these new materials and device packaging methods promise to enable the fabrication of IV-VI mid-IR lasers with cw operation at room temperature.

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33

Partin, Dale L. "Preparation and Applications of Lead Chalcogenide Diode Lasers." MRS Proceedings 90 (1986). http://dx.doi.org/10.1557/proc-90-47.

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ABSTRACTLead chalcogenide diode lasers are useful for spectroscopic and fiber optics applications in the mid-infrared (2.5-30 μm) wavelength range. These devices have previously required cryogenic cooling (<100 K) for CW operation. This limitation has been overcome through the use of a new, lattice-matched alloy system, Pb1-xEuxSeyTe1-y as well as the introduction of advanced, quantum well active region device structures grown by molecular beam epitaxy (MBE). Operating temperatures have been increased to 175 K CW (at 4.4 μm) and to 270 K pulsed (at 3.9 μm). Thermal leakage currents out of the device active region appear to be limiting device performance. This has led to the study of band offsets in PbEuSeTe/PbTe heterojunctions as well as to exploration of alternative high energy band gap alloys of PbTe with Ge, Yb, Ca, Sr, and Ba. The status of this work and examples of ultrahigh resolution studies done with these tunable laser sources will be included.

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Weber, J. K. R., C. J. Benmore, M. C. Wilding, J. Neuefeind, and J. B. Parise. "Instrumentation for structure measurements on highly non-equilibrium materials." Diamond Light Source Proceedings 1, SRMS-7 (February 2011). http://dx.doi.org/10.1017/s2044820110000080.

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Containerless techniques (levitation) completely eliminate contact with the sample. This unique sample environment allows deep supercooling of many liquids and avoids contamination of high-temperature melts. Recent experiments at the Advanced Photon Source (APS) high-energy beamline 11 ID-C used aerodynamic levitation with laser beam heating and acoustic levitation with cryogenic cooling. By using these two methods, liquids were studied over much of the temperature range from −40 to +2500°C. This paper briefly describes the instrumentation and its use and is illustrated with examples of measurements on molten oxides and low-temperature liquids.

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Venkatasubramanian, Rama, Brooks O'Quinn, Edward Siivola, Kip Coonley, Pratima Addepally, Mary Napier, and Thomas Colpitts. "Superlattice Thin-film Thermoelectric Materials and Devices." MRS Proceedings 793 (2003). http://dx.doi.org/10.1557/proc-793-s2.3.

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ABSTRACTThin-film nano-structured materials offer the potential to enhance the performance of thermoelectrics, with near-term capabilities like small-footprint coolers for lasers and microprocessors. Our recent focus has been to transition the enhanced figure-of-merit (ZT) in p-type Bi2Te3/Sb2Te3 and n-type Bi2Te3/Bi2Te3-xSex superlattices to performance at the module level with several device demonstrations. We have been able to obtain a best ZT of ∼2 in a p-n couple, the fundamental cooling or power conversion unit in an operational module. In addition, we have been able to demonstrate p-n couple ZT of as much as 1.6 from heat-to-power efficiency data. The thermal interface resistances between the active device and the external heat source have been optimized. A power level of 38 mW per couple for a ΔT of about 107K, with 4-micron-thick element, was obtained. This translates to an active power density of ∼54 W/cm2 and a mini-module power density of ∼10.5 W/cm2. In short, power devices with thin-film superlattices are a real possibility. In the cooling arena, we have been able to obtain over 50K active cooling with thin-film modules, useable in several laser and microprocessor cooling needs. This is in spite of severe thermal management issues that had to be overcome noting that the “true” hot-side temperature, and hence the “true” ΔT, across the device are much higher. Even so, we have p-n superlattice couples that show twice the cooling ΔTmax, compared to the best bulk p-n couples at cryogenic temperatures. Some of the challenges that remain to be addressed in the full development of this materials technology and thoughts on further progress in nano-structured materials are presented.

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Journal articles on the topic 'Cryogenics; Laser cooling'

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