Hui Chen, D. T. Woods, N. Lemos, M. Rosen, O. Landen, J. Milovich, M. B. Schneider, C. Trosseille, J. Delora-Ellefson, M. Hardy, N. Hash, D. Hinkel, J. Holder, N. Izumi, N. Masters, W. Montgomery, J. D. Moody, K. Newman, S. Rogers, J. S. Ross, V. Smalyuk, C. Weber, T. Zobrist
In a National Ignition Facility (NIF) cylindrical hohlraum, any specular reflection (“glint”) off the wall from the outer cone (incident angle of 50° and 44° relative to the surface of the wall) laser beam will irradiate the capsule poles. If the glint power is sufficiently large during the picket (early time) of the laser pulse, it may seed high-mode perturbations on the capsule surface that can grow during the implosion. To quantify the glint power on the capsule during the picket by the outer beams, we performed dedicated experiments on NIF using a flat witness foil as a surrogate for the capsule in a half-hohlraum target. We found that the measured glint power is approximately comparable to simulations using a nominal electron conduction flux limiter of f = 0.15, and over an order of magnitude lower than that predicted using f = 0.03 in the wall. Based on our current understanding, we conclude that the glint from the outer beams plays an insignificant role in capsule drive asymmetry.
在国家点火装置（NIF）的圆柱形光室中，外锥体（相对于光室壁表面的入射角为 50° 和 44°）激光束在光室壁上的任何镜面反射（"闪烁"）都会照射到光室的两极。如果在激光脉冲的拾取期间（早期）闪烁功率足够大，则可能会在胶囊表面产生高模扰动，这些扰动会在内爆期间增长。为了量化外光束拾取期间胶囊上的熠射功率，我们在 NIF 上进行了专门的实验，使用平面见证箔片作为半红外目标中胶囊的替代物。我们发现，测得的闪烁功率与使用 f = 0.15 的额定电子传导通量限制器进行的模拟结果大致相当，而比使用 f = 0.03 的壁预测值低一个数量级以上。根据我们目前的理解，我们得出结论：外束的闪烁在太空舱驱动不对称中的作用微乎其微。
{"title":"Measurement of early time outer laser beam reflection inside a cylindrical hohlraum at the National Ignition Facility","authors":"Hui Chen, D. T. Woods, N. Lemos, M. Rosen, O. Landen, J. Milovich, M. B. Schneider, C. Trosseille, J. Delora-Ellefson, M. Hardy, N. Hash, D. Hinkel, J. Holder, N. Izumi, N. Masters, W. Montgomery, J. D. Moody, K. Newman, S. Rogers, J. S. Ross, V. Smalyuk, C. Weber, T. Zobrist","doi":"10.1063/5.0201962","DOIUrl":"https://doi.org/10.1063/5.0201962","url":null,"abstract":"In a National Ignition Facility (NIF) cylindrical hohlraum, any specular reflection (“glint”) off the wall from the outer cone (incident angle of 50° and 44° relative to the surface of the wall) laser beam will irradiate the capsule poles. If the glint power is sufficiently large during the picket (early time) of the laser pulse, it may seed high-mode perturbations on the capsule surface that can grow during the implosion. To quantify the glint power on the capsule during the picket by the outer beams, we performed dedicated experiments on NIF using a flat witness foil as a surrogate for the capsule in a half-hohlraum target. We found that the measured glint power is approximately comparable to simulations using a nominal electron conduction flux limiter of f = 0.15, and over an order of magnitude lower than that predicted using f = 0.03 in the wall. Based on our current understanding, we conclude that the glint from the outer beams plays an insignificant role in capsule drive asymmetry.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"57 49","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141275022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sha Xu, L. Lei, Ziyun Yao, Yong Zhang, F. Qin, Yue Cui, Zhi-kai Fan, Dong Wang
To address the inherent power limitations in a single relativistic magnetron (RM), we explore the feasibility of coupling multiple phase-locked RMs without compromising power conversion efficiencies. Successful phase locking of two coupled A6 RMs, where radiations are axially extracted as TE11 modes, has been achieved. The interaction between the two RMs is facilitated by a well-designed waveguide with a transmission coefficient exceeding 98% in the L-band. In our designed system, as per the particle-in-cell simulation results with a diode voltage of 560 kV, the RMs' peak power of the Gaussian radiation pattern reaches approximately 3.4 GW. The relative phase jitter between these two tubes is effectively controlled within ±1.6%, and the power conversion efficiency reaches up to 48.1%. This study presents a viable approach to enhance the output power of RMs while maintaining phase-locked Gaussian radiation patterns.
{"title":"Coupled relativistic magnetrons with phase-locked Gaussian radiation pattern","authors":"Sha Xu, L. Lei, Ziyun Yao, Yong Zhang, F. Qin, Yue Cui, Zhi-kai Fan, Dong Wang","doi":"10.1063/5.0206029","DOIUrl":"https://doi.org/10.1063/5.0206029","url":null,"abstract":"To address the inherent power limitations in a single relativistic magnetron (RM), we explore the feasibility of coupling multiple phase-locked RMs without compromising power conversion efficiencies. Successful phase locking of two coupled A6 RMs, where radiations are axially extracted as TE11 modes, has been achieved. The interaction between the two RMs is facilitated by a well-designed waveguide with a transmission coefficient exceeding 98% in the L-band. In our designed system, as per the particle-in-cell simulation results with a diode voltage of 560 kV, the RMs' peak power of the Gaussian radiation pattern reaches approximately 3.4 GW. The relative phase jitter between these two tubes is effectively controlled within ±1.6%, and the power conversion efficiency reaches up to 48.1%. This study presents a viable approach to enhance the output power of RMs while maintaining phase-locked Gaussian radiation patterns.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"54 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141280126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Frank, J. C. Wright, P. Rodriguez-Fernandez, N. T. Howard, P. Bonoli
Reproducing fast-ion enhanced fusion rates from ion-cyclotron resonance heating (ICRH) in tokamaks requires the self-consistent coupling of a full-wave solver and a Fokker–Planck solver, which evolves multiple simultaneously resonant ion species. We introduce a new self-consistent model that iterates the TORIC full-wave solver with the CQL3D Fokker–Planck solver using the integrated plasma simulator (IPS). This model evolves the bounce-averaged ion distribution functions in both parallel and perpendicular velocity-space with a quasilinear radio frequency (RF) diffusion operator valid in the ion finite Larmor radius (FLR) limit and the RF electric fields with the resultant non-Maxwellian FLR dielectric tensor. This produces non-Maxwellian ICRH simulations that are fully self-consistent, fast, and interoperable with integrated modeling frameworks, such as TRANSP/GACODE/IPS-FASTRAN. We demonstrate our model's capabilities by validating it against experimental data in Alcator C-Mod. We then perform the first RF heating simulations of SPARC using self-consistent non-Maxwellian ion distributions to investigate the potential to enhance fusion rates using ion cyclotron resonance heating generated fast ions.
{"title":"Simulating energetic ions and enhanced fusion rates from ion-cyclotron resonance heating with a full-wave/Fokker–Planck model","authors":"S. Frank, J. C. Wright, P. Rodriguez-Fernandez, N. T. Howard, P. Bonoli","doi":"10.1063/5.0204671","DOIUrl":"https://doi.org/10.1063/5.0204671","url":null,"abstract":"Reproducing fast-ion enhanced fusion rates from ion-cyclotron resonance heating (ICRH) in tokamaks requires the self-consistent coupling of a full-wave solver and a Fokker–Planck solver, which evolves multiple simultaneously resonant ion species. We introduce a new self-consistent model that iterates the TORIC full-wave solver with the CQL3D Fokker–Planck solver using the integrated plasma simulator (IPS). This model evolves the bounce-averaged ion distribution functions in both parallel and perpendicular velocity-space with a quasilinear radio frequency (RF) diffusion operator valid in the ion finite Larmor radius (FLR) limit and the RF electric fields with the resultant non-Maxwellian FLR dielectric tensor. This produces non-Maxwellian ICRH simulations that are fully self-consistent, fast, and interoperable with integrated modeling frameworks, such as TRANSP/GACODE/IPS-FASTRAN. We demonstrate our model's capabilities by validating it against experimental data in Alcator C-Mod. We then perform the first RF heating simulations of SPARC using self-consistent non-Maxwellian ion distributions to investigate the potential to enhance fusion rates using ion cyclotron resonance heating generated fast ions.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"12 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141274521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new experimental method for creating void-free complex (dusty) plasmas under microgravity conditions is presented. The method is based on a pulsed operation mode of a four-channel radio frequency generator for plasma sustainment. A dust cloud of micrometer-sized particles can be immersed in the bulk of a low temperature plasma under microgravity conditions. It typically contains a central volume depleted of particles—the void—that prevents the generation of large, continuous clouds. Experiments performed at different neutral gas pressures and discharge volumes during the microgravity phase of a parabolic flight show that the central void is closed completely once the pulsed operation mode is applied. The particle cloud shape and the density distribution within the cloud are practically independent of the pulse period within the investigated parameter range and mainly depend on the overall discharge parameters neutral gas pressure and discharge volume. This indicates that the pulsed operation of the plasma source does not introduce new physical effects on the particles aside from the void closure. The proposed method has great potential for future application in experimental facilities dedicated to fundamental studies of large three-dimensional, homogeneous complex plasma systems in microgravity.
{"title":"Void closure in a pulsed complex plasma in microgravity","authors":"C. Knapek, D. Mohr, P. Huber","doi":"10.1063/5.0204998","DOIUrl":"https://doi.org/10.1063/5.0204998","url":null,"abstract":"A new experimental method for creating void-free complex (dusty) plasmas under microgravity conditions is presented. The method is based on a pulsed operation mode of a four-channel radio frequency generator for plasma sustainment. A dust cloud of micrometer-sized particles can be immersed in the bulk of a low temperature plasma under microgravity conditions. It typically contains a central volume depleted of particles—the void—that prevents the generation of large, continuous clouds. Experiments performed at different neutral gas pressures and discharge volumes during the microgravity phase of a parabolic flight show that the central void is closed completely once the pulsed operation mode is applied. The particle cloud shape and the density distribution within the cloud are practically independent of the pulse period within the investigated parameter range and mainly depend on the overall discharge parameters neutral gas pressure and discharge volume. This indicates that the pulsed operation of the plasma source does not introduce new physical effects on the particles aside from the void closure. The proposed method has great potential for future application in experimental facilities dedicated to fundamental studies of large three-dimensional, homogeneous complex plasma systems in microgravity.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"56 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141275711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work presents a theoretical analysis of the generation of twisted terahertz (THz) radiation using laser-bunched relativistic electron beams in a magnetic wiggler. By employing a laser-bunched relativistic electron beam, which introduces a transverse modulation to the electron beam density, and a magnetic wiggler, which induces a transverse deflection to the electron trajectories, the generation of twisted THz radiation is achieved. The interaction between the modulated electron beam and the magnetic field leads to the emission of THz photons with a twisted phase structure. The findings of this study provide valuable insights into the generation and manipulation of twisted THz radiation contributing to the advancement of THz technology and its diverse applications.
{"title":"Twisted terahertz excitation using pre-bunched relativistic electron beam in magnetic wiggler","authors":"Himani Juneja, A. Panwar, Prashant Chauhan","doi":"10.1063/5.0206098","DOIUrl":"https://doi.org/10.1063/5.0206098","url":null,"abstract":"This work presents a theoretical analysis of the generation of twisted terahertz (THz) radiation using laser-bunched relativistic electron beams in a magnetic wiggler. By employing a laser-bunched relativistic electron beam, which introduces a transverse modulation to the electron beam density, and a magnetic wiggler, which induces a transverse deflection to the electron trajectories, the generation of twisted THz radiation is achieved. The interaction between the modulated electron beam and the magnetic field leads to the emission of THz photons with a twisted phase structure. The findings of this study provide valuable insights into the generation and manipulation of twisted THz radiation contributing to the advancement of THz technology and its diverse applications.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"17 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141279376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhipeng Liu, Ying Gao, Qingfan Wu, Z. Pan, Yulan Liang, Tan Song, Tianqi Xu, Y. Shou, Yujia Zhang, Haoran Chen, Qihang Han, Chenghao Hua, Xun Chen, Shirui Xu, Z. Mei, Pengjie Wang, Z.-K. Peng, Jiarui Zhao, Shiyou Chen, Yanying Zhao, Xueqing Yan, Wenjun Ma
In proton acceleration from laser-irradiated thin foil targets, adding foams on the front surface or connecting a helical coil on the rear surface of the foil has proven to be an effective scheme to enhance proton energy. In this paper, we make the first attempt to incorporate the above two enhancement schemes for laser-proton acceleration by simultaneously adding foams and connecting a helical coil to a thin foil target. By utilizing such integrated targets in the experiment, focused beams were generated. The maximum proton energy and the number of energetic protons are apparently enhanced. Moreover, quasi-monoenergetic peaks were formed at the high-energy end of the spectra. Particle-in-cell plasma simulations and electromagnetic beam dynamics simulations show that the double-layer target not only enhances the energy of protons but also leads to a multiple-fold increase in the number of escaped electrons, which results in an enhanced post-acceleration in helical coil subsequently.
{"title":"Synergistic enhancement of laser-proton acceleration with integrated targets","authors":"Zhipeng Liu, Ying Gao, Qingfan Wu, Z. Pan, Yulan Liang, Tan Song, Tianqi Xu, Y. Shou, Yujia Zhang, Haoran Chen, Qihang Han, Chenghao Hua, Xun Chen, Shirui Xu, Z. Mei, Pengjie Wang, Z.-K. Peng, Jiarui Zhao, Shiyou Chen, Yanying Zhao, Xueqing Yan, Wenjun Ma","doi":"10.1063/5.0195634","DOIUrl":"https://doi.org/10.1063/5.0195634","url":null,"abstract":"In proton acceleration from laser-irradiated thin foil targets, adding foams on the front surface or connecting a helical coil on the rear surface of the foil has proven to be an effective scheme to enhance proton energy. In this paper, we make the first attempt to incorporate the above two enhancement schemes for laser-proton acceleration by simultaneously adding foams and connecting a helical coil to a thin foil target. By utilizing such integrated targets in the experiment, focused beams were generated. The maximum proton energy and the number of energetic protons are apparently enhanced. Moreover, quasi-monoenergetic peaks were formed at the high-energy end of the spectra. Particle-in-cell plasma simulations and electromagnetic beam dynamics simulations show that the double-layer target not only enhances the energy of protons but also leads to a multiple-fold increase in the number of escaped electrons, which results in an enhanced post-acceleration in helical coil subsequently.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"26 38","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141137299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The method of expulsion of hydrogen negative ions in the axial direction by a negative space charge formed in the plasma of Penning discharge with metal hydride cathodes is discussed. The plasma is produced on hydrogen, which is stored in metal hydride cathodes and injected locally into the discharge cell without any external gas supply due to ion current impact from plasma. The process of nonequilibrium desorption resulted in high vibrational excitation of H2 molecules, which greatly increases the efficiency of H− ion production. The method of efficient expulsion of H− ions depends on the external magnetic field. At a high magnetic field, it is performed by the supply of negative electric bias of the opposite cathode, but at a low one, H− ions are pushed out by the negative space charge of the anode layer, which expands toward the axis. The impact of both methods is considered in the case of DC discharge and in pulsating regime implementation.
本论文讨论了通过在带金属氢化物阴极的潘宁放电等离子体中形成的负空间电荷沿轴向排出氢负离子的方法。等离子体是在氢气上产生的，氢气储存在金属氢化物阴极中，由于等离子体的离子流冲击，在没有任何外部气体供应的情况下就地注入放电池。非平衡解吸过程导致了氢分子的高振动激发，从而大大提高了氢离子的产生效率。高效驱逐 H 离子的方法取决于外部磁场。在高磁场下，通过提供反向阴极的负电偏压来实现，但在低磁场下，H 离子被阳极层的负空间电荷推向轴心。这两种方法在直流放电和脉动放电情况下都有影响。
{"title":"Expulsion of hydrogen negative ions by the anode layer of negative space charge from Penning discharge with metal hydride cathodes","authors":"I. Sereda, Y. Hrechko, M. Azarenkov","doi":"10.1063/5.0202579","DOIUrl":"https://doi.org/10.1063/5.0202579","url":null,"abstract":"The method of expulsion of hydrogen negative ions in the axial direction by a negative space charge formed in the plasma of Penning discharge with metal hydride cathodes is discussed. The plasma is produced on hydrogen, which is stored in metal hydride cathodes and injected locally into the discharge cell without any external gas supply due to ion current impact from plasma. The process of nonequilibrium desorption resulted in high vibrational excitation of H2 molecules, which greatly increases the efficiency of H− ion production. The method of efficient expulsion of H− ions depends on the external magnetic field. At a high magnetic field, it is performed by the supply of negative electric bias of the opposite cathode, but at a low one, H− ions are pushed out by the negative space charge of the anode layer, which expands toward the axis. The impact of both methods is considered in the case of DC discharge and in pulsating regime implementation.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"64 1‐2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141134085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vortex gas is an approximation used to study 2D flow using statistical mechanics methodologies. We investigate low positive Onsager temperature states for the vortex gas on an annular domain. Using mean field theory, microcanonical sampling of the point gas model, and canonical sampling of a lattice model, we find evidence for edge modes at low energy states.
{"title":"Edge modes of the Helmholtz–Onsager gas in a multiply connected domain","authors":"Richard McQueen, Chjan C. Lim","doi":"10.1063/5.0193438","DOIUrl":"https://doi.org/10.1063/5.0193438","url":null,"abstract":"The vortex gas is an approximation used to study 2D flow using statistical mechanics methodologies. We investigate low positive Onsager temperature states for the vortex gas on an annular domain. Using mean field theory, microcanonical sampling of the point gas model, and canonical sampling of a lattice model, we find evidence for edge modes at low energy states.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"76 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141143246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Gromelski, C. Angioni, A. Chomiczewska, D. Fajardo, I. Ivanova-Stanik, Damian King, E. Kowalska-Strzęciwilk, M. Maslov, E. Pawelec, P. Schneider
The work presents the recent outcome of the research on Joint European Torus with ITER-like wall (JET-ILW) concerning Be, mid-Z (Ni, Cu, Fe), and high-Z (W) impurities for a selection of Neutral Beam Injection-heated, ELMy H-mode pulses using visible and vacuum–ultraviolet spectroscopy together with bolometry diagnostic. The investigation is focused on the evaluation of the plasma triangularity (δ) impact on the impurity radiation in hydrogen (H), deuterium (D), tritium (T), and deuterium–tritium (DT) plasmas for pulses described in [P. A. Schneider, Nucl. Fusion 63, 112010 (2023)]. The variations of δ were in the range of 0.21–0.31 for different time windows with low magnetic toroidal field (Bt=1.7 T) and plasma current (Ip=1.4 MA) in the corner–corner configuration, that is with both the inner and outer strike points on the horizontal W-coated divertor target plates. The results confirm the rise in Be flux with plasma isotope and lower δ leading to higher plasma density close to the plasma wall. The dominant role of W as a source of plasma radiation has also been confirmed. For mid-Z impurities and W, the variations in their densities due to δ change are negligible and the rise in their densities is observed with higher isotope mass, although this effect is often masked by the dominant role of ELM frequency on the impurity level. The impurity radiation losses based on bolometry together with the W intensity are ruled by the changes in the electron density and are well correlated when the Te profiles are conserved.
这项工作介绍了利用可见光和真空-紫外光谱以及螺栓测量诊断法，在具有类似热核聚变实验堆壁的欧洲联合火炬（JET-ILW）上对中性束注入加热、ELMy H 模式脉冲中的 Be、中 Z（Ni、Cu、Fe）和高 Z（W）杂质进行研究的最新成果。调查的重点是评估等离子体三角形（δ）对氢（H）、氘（D）、氚（T）和氘氚（DT）等等离子体中杂质辐射的影响，脉冲情况见[P. A. Schneider, Nucl. Fusion 63, 112010 (2023)]。在低磁环形场（Bt=1.7 T）和等离子体电流（Ip=1.4 MA）的角-角配置（即水平 W 涂层岔流靶板上的内外撞击点）下的不同时间窗口中，δ 的变化范围为 0.21-0.31。结果证实，Be 通量随等离子体同位素和较低 δ 的增加而增加，导致靠近等离子体壁的等离子体密度增加。W 作为等离子体辐射源的主导作用也得到了证实。对于中 Z 杂质和 W 来说，δ 变化引起的密度变化可以忽略不计，随着同位素质量的增加，它们的密度也会增加，不过这种影响往往会被 ELM 频率对杂质水平的主导作用所掩盖。基于螺栓测量法的杂质辐射损耗和 W 强度受电子密度变化的影响，并且在 Te 曲线保持不变的情况下具有良好的相关性。
{"title":"Investigation of triangularity impact on impurity content in JET-ILW H, D, T, and DT plasmas","authors":"W. Gromelski, C. Angioni, A. Chomiczewska, D. Fajardo, I. Ivanova-Stanik, Damian King, E. Kowalska-Strzęciwilk, M. Maslov, E. Pawelec, P. Schneider","doi":"10.1063/5.0207343","DOIUrl":"https://doi.org/10.1063/5.0207343","url":null,"abstract":"The work presents the recent outcome of the research on Joint European Torus with ITER-like wall (JET-ILW) concerning Be, mid-Z (Ni, Cu, Fe), and high-Z (W) impurities for a selection of Neutral Beam Injection-heated, ELMy H-mode pulses using visible and vacuum–ultraviolet spectroscopy together with bolometry diagnostic. The investigation is focused on the evaluation of the plasma triangularity (δ) impact on the impurity radiation in hydrogen (H), deuterium (D), tritium (T), and deuterium–tritium (DT) plasmas for pulses described in [P. A. Schneider, Nucl. Fusion 63, 112010 (2023)]. The variations of δ were in the range of 0.21–0.31 for different time windows with low magnetic toroidal field (Bt=1.7 T) and plasma current (Ip=1.4 MA) in the corner–corner configuration, that is with both the inner and outer strike points on the horizontal W-coated divertor target plates. The results confirm the rise in Be flux with plasma isotope and lower δ leading to higher plasma density close to the plasma wall. The dominant role of W as a source of plasma radiation has also been confirmed. For mid-Z impurities and W, the variations in their densities due to δ change are negligible and the rise in their densities is observed with higher isotope mass, although this effect is often masked by the dominant role of ELM frequency on the impurity level. The impurity radiation losses based on bolometry together with the W intensity are ruled by the changes in the electron density and are well correlated when the Te profiles are conserved.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"154 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141133674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The propagation of electromagnetic beams carrying orbital angular momentum l is investigated in a cold collisionless plasma where a static magnetic field is applied in the axial direction. The relativistic and ponderomotive nonlinearities are taken into consideration simultaneously. A stationary nonlinear Schrödinger equation is derived using the Wentzel–Kramers–Brillouin method and the slowly varying envelope approximation. The critical condition for the self-trapped mode is achieved as a function of orbital angular momentum (OAM), magnetic field, and initial laser intensity of the beam. The response of the medium to the two types of polarizations, i.e., left circular polarization (LCP) and right circular polarization (RCP), is compared, and it is observed that the RCP laser shows better focusing than the LCP laser and also requires a smaller beam radius for achieving the self-trapped mode. The effect of applied magnetic field and OAM of the laser is also studied on the beam width evolution. The laser is found to be focused earlier in the cases of a larger applied magnetic field. A Laguerre–Gaussian laser with higher OAM is observed to show efficient self-focusing. This study enables exploration in the fields of particle acceleration, electron bunch generation, x-ray sources, and more.
{"title":"Propagation of twisted laser carrying orbital angular momentum in magnetized plasma","authors":"Subhajit Bhaskar, Hitendra K. Malik","doi":"10.1063/5.0206828","DOIUrl":"https://doi.org/10.1063/5.0206828","url":null,"abstract":"The propagation of electromagnetic beams carrying orbital angular momentum l is investigated in a cold collisionless plasma where a static magnetic field is applied in the axial direction. The relativistic and ponderomotive nonlinearities are taken into consideration simultaneously. A stationary nonlinear Schrödinger equation is derived using the Wentzel–Kramers–Brillouin method and the slowly varying envelope approximation. The critical condition for the self-trapped mode is achieved as a function of orbital angular momentum (OAM), magnetic field, and initial laser intensity of the beam. The response of the medium to the two types of polarizations, i.e., left circular polarization (LCP) and right circular polarization (RCP), is compared, and it is observed that the RCP laser shows better focusing than the LCP laser and also requires a smaller beam radius for achieving the self-trapped mode. The effect of applied magnetic field and OAM of the laser is also studied on the beam width evolution. The laser is found to be focused earlier in the cases of a larger applied magnetic field. A Laguerre–Gaussian laser with higher OAM is observed to show efficient self-focusing. This study enables exploration in the fields of particle acceleration, electron bunch generation, x-ray sources, and more.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"98 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141135665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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