High-intensity lasers are critical for exploring the laser–matter interactions. Here, we propose a scheme to enhance the light intensity of petawatt (PW) lasers. The scheme is based on a hollow solid plasma cone that is formed by the multiphoton ionization of PW lasers. The influence of the length and radius of the cone on laser intensity enhancement is systematically studied. After tight focusing by the plasma cone, the spot size is 1 × 1 μm2. Two-dimensional particle-in-cell (PIC) simulations predict an intensity enhancement of a laser pulse from 5.3×1021 to 5.5×1022 W/cm2—a ratio of 10. In addition, the focusing position of the laser can be either inside or outside the cone. Such powerful lasers can be used to increase the energy of gamma photons radiated in laser solid–target interactions. PIC simulations reveal that compared with the case without a plasma cone, both the maximum energy and yield of gamma photons are increased significantly. As plasma is robust and resistant to damage at high intensities, the plasma cone should be used as a complementary optical element to achieve higher laser intensity on existing PW laser facilities.
{"title":"PW laser intensity enhancement by a hollow solid plasma cone","authors":"Xiaolong Zheng, Xiaomei Zhang, Baifei Shen","doi":"10.1063/5.0219701","DOIUrl":"https://doi.org/10.1063/5.0219701","url":null,"abstract":"High-intensity lasers are critical for exploring the laser–matter interactions. Here, we propose a scheme to enhance the light intensity of petawatt (PW) lasers. The scheme is based on a hollow solid plasma cone that is formed by the multiphoton ionization of PW lasers. The influence of the length and radius of the cone on laser intensity enhancement is systematically studied. After tight focusing by the plasma cone, the spot size is 1 × 1 μm2. Two-dimensional particle-in-cell (PIC) simulations predict an intensity enhancement of a laser pulse from 5.3×1021 to 5.5×1022 W/cm2—a ratio of 10. In addition, the focusing position of the laser can be either inside or outside the cone. Such powerful lasers can be used to increase the energy of gamma photons radiated in laser solid–target interactions. PIC simulations reveal that compared with the case without a plasma cone, both the maximum energy and yield of gamma photons are increased significantly. As plasma is robust and resistant to damage at high intensities, the plasma cone should be used as a complementary optical element to achieve higher laser intensity on existing PW laser facilities.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"28 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metaplectic geometrical optics (MGO) is a recently developed ray-tracing framework to accurately compute the wavefield behavior near a caustic (turning point or focal point), where traditional ray-tracing breaks down. However, MGO has thus far been restricted to having real-valued wavevectors. This is disadvantageous because often upon crossing a caustic from the “illuminated” region to the “shadow” region, two real-valued rays coalesce into one complex-valued ray corresponding to the transition from propagating to evanescent behavior. One can distinguish caustics as having either “illuminated shadows” or “proper shadows”—the former corresponds to when the shadow still contains real-valued rays (albeit in a fewer quantity than in the illuminated region), while the latter corresponds to when the shadow contains no real-valued rays. Here, by means of examples, we show how MGO can be used to model both types of shadows. First, for illuminated shadows, we show that MGO can actually be used “as is,” provided a corrected integration scheme is used compared to that proposed in the original references. This is then implemented and demonstrated in a recently developed MGO ray-tracing code. Second, we show that for proper shadows, the MGO formalism can still be used if the symplectic rotation matrix that removes caustics along rays is allowed to be complex-valued. In both cases, strong agreement is seen between the MGO and the exact solution, demonstrating the potential of MGO for improving the predictive capability of ray-tracing codes and laying the foundations for modeling more complicated evanescent phenomena such as tunneling with MGO.
{"title":"Regarding the extension of metaplectic geometrical optics to modeling evanescent waves in ray-tracing codes","authors":"N. A. Lopez, R. Højlund, M. G. Senstius","doi":"10.1063/5.0221784","DOIUrl":"https://doi.org/10.1063/5.0221784","url":null,"abstract":"Metaplectic geometrical optics (MGO) is a recently developed ray-tracing framework to accurately compute the wavefield behavior near a caustic (turning point or focal point), where traditional ray-tracing breaks down. However, MGO has thus far been restricted to having real-valued wavevectors. This is disadvantageous because often upon crossing a caustic from the “illuminated” region to the “shadow” region, two real-valued rays coalesce into one complex-valued ray corresponding to the transition from propagating to evanescent behavior. One can distinguish caustics as having either “illuminated shadows” or “proper shadows”—the former corresponds to when the shadow still contains real-valued rays (albeit in a fewer quantity than in the illuminated region), while the latter corresponds to when the shadow contains no real-valued rays. Here, by means of examples, we show how MGO can be used to model both types of shadows. First, for illuminated shadows, we show that MGO can actually be used “as is,” provided a corrected integration scheme is used compared to that proposed in the original references. This is then implemented and demonstrated in a recently developed MGO ray-tracing code. Second, we show that for proper shadows, the MGO formalism can still be used if the symplectic rotation matrix that removes caustics along rays is allowed to be complex-valued. In both cases, strong agreement is seen between the MGO and the exact solution, demonstrating the potential of MGO for improving the predictive capability of ray-tracing codes and laying the foundations for modeling more complicated evanescent phenomena such as tunneling with MGO.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"35 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This comment discusses the feasibility of hot ion mode Ti/Te=4 for proton–boron fusion, which is critical for the roadmap proposed in Liu et al. [Phys. Plasmas 31, 062507 (2024)]. The hot ion mode Ti/Te=4 has been calculated to be far from accessible (Ti/Te<1.5 for Ti=150 keV) under the most optimal conditions if fusion provides the heating [Xie, Introduction to Fusion Ignition Principles: Zeroth Order Factors of Fusion Energy Research (USTC Press, Hefei, 2023)], i.e., that all fusion power serves to heat the ions and that electrons acquire energy only through interactions with ions. We also discuss if hot ion mode of Ti/Te=4 could be achieved by an ideal heating method, which is much more efficient than fusion itself (near 20 times fusion power for Ti=150 keV) and only heats the ions, whether it makes sense economically.
{"title":"Comment on “ENN's roadmap for proton-boron fusion based on spherical torus” [Phys. Plasmas 31, 062507 (2024)]","authors":"Zhi Li","doi":"10.1063/5.0223575","DOIUrl":"https://doi.org/10.1063/5.0223575","url":null,"abstract":"This comment discusses the feasibility of hot ion mode Ti/Te=4 for proton–boron fusion, which is critical for the roadmap proposed in Liu et al. [Phys. Plasmas 31, 062507 (2024)]. The hot ion mode Ti/Te=4 has been calculated to be far from accessible (Ti/Te&lt;1.5 for Ti=150 keV) under the most optimal conditions if fusion provides the heating [Xie, Introduction to Fusion Ignition Principles: Zeroth Order Factors of Fusion Energy Research (USTC Press, Hefei, 2023)], i.e., that all fusion power serves to heat the ions and that electrons acquire energy only through interactions with ions. We also discuss if hot ion mode of Ti/Te=4 could be achieved by an ideal heating method, which is much more efficient than fusion itself (near 20 times fusion power for Ti=150 keV) and only heats the ions, whether it makes sense economically.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"59 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to improve the surface flashover strength of the insulation materials and solve the problem that the relatively high price of CF4 restricts the large-scale application of fluorination modification of CF4 atmospheric pressure plasma jet (APPJ) in the industrial field, He/CF4/O2 APPJ with different O2 content is used to treat epoxy resin (EP) dielectric material. By analyzing the results of scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy, the influence of O2 content on the multiple characteristics of EP surface before and after APPJ treatment is studied. Flashover experiment is also carried out on EP surface before and after APPJ treatment. It is found that the addition of 0.1% O2 can increase the mature voltage of the EP surface by about 16.10% compared with untreated EP surface. It is concluded that the improvement of the surface flashover strength with a small amount of O2 (within 0.1%) is influenced by the surface roughness and chemical composition of the dielectric. The deposition effect of APPJ on EP surface is enhanced to increase the surface roughness and reaches the best at 0.1% O2, because the addition of excessive O2 will weaken the APPJ intensity. It is speculated that the creepage distance of the EP surface is increased to inhibit the formation of electron collapse and the content of electronegative fluorine and oxygen on the EP surface is increased under a small amount of O2 addition, resulting in the inhibition of the formation of surface flashover.
为了提高绝缘材料的表面闪蒸强度，解决CF4价格较高制约CF4常压等离子体射流（APPJ）氟化改性在工业领域大规模应用的问题，采用不同O2含量的He/CF4/O2 APPJ处理环氧树脂（EP）介电材料。通过分析扫描电子显微镜、原子力显微镜和 X 射线光电子能谱的结果，研究了氧气含量对 APPJ 处理前后环氧树脂表面多种特性的影响。还对 APPJ 处理前后的 EP 表面进行了闪蒸实验。结果发现，与未处理的 EP 表面相比，添加 0.1% 的 O2 可使 EP 表面的成熟电压提高约 16.10%。由此得出结论，少量氧气（0.1% 以内）对表面闪蒸强度的改善受表面粗糙度和电介质化学成分的影响。APPJ 在 EP 表面的沉积效果会随着表面粗糙度的增加而增强，并在 0.1% O2 时达到最佳效果，因为过量的 O2 会削弱 APPJ 的强度。据推测，在添加少量 O2 的情况下，EP 表面的爬电距离增加以抑制电子塌缩的形成，EP 表面的负电性氟和氧含量增加，从而抑制了表面闪蒸的形成。
{"title":"Influence of O2 content on surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet to improve surface flashover strength","authors":"Lijun Wang, Huan Zhao, Jie Liu, Yile Wang","doi":"10.1063/5.0218575","DOIUrl":"https://doi.org/10.1063/5.0218575","url":null,"abstract":"In order to improve the surface flashover strength of the insulation materials and solve the problem that the relatively high price of CF4 restricts the large-scale application of fluorination modification of CF4 atmospheric pressure plasma jet (APPJ) in the industrial field, He/CF4/O2 APPJ with different O2 content is used to treat epoxy resin (EP) dielectric material. By analyzing the results of scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy, the influence of O2 content on the multiple characteristics of EP surface before and after APPJ treatment is studied. Flashover experiment is also carried out on EP surface before and after APPJ treatment. It is found that the addition of 0.1% O2 can increase the mature voltage of the EP surface by about 16.10% compared with untreated EP surface. It is concluded that the improvement of the surface flashover strength with a small amount of O2 (within 0.1%) is influenced by the surface roughness and chemical composition of the dielectric. The deposition effect of APPJ on EP surface is enhanced to increase the surface roughness and reaches the best at 0.1% O2, because the addition of excessive O2 will weaken the APPJ intensity. It is speculated that the creepage distance of the EP surface is increased to inhibit the formation of electron collapse and the content of electronegative fluorine and oxygen on the EP surface is increased under a small amount of O2 addition, resulting in the inhibition of the formation of surface flashover.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"28 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Relativistic electromagnetic plasma waves are described by a dynamical equation that can be solved not only in terms of plane waves, but also for several different accelerating wavepacket solutions. Depending on the spatial and temporal dependence of the plasma frequency, different kinds of accelerating solutions can be obtained, for example, in terms of Airy or Weber functions. Also, we show that an arbitrary accelerated wavepacket solution is possible, for example, for a system with a luminal plasma slab.
{"title":"Different kinds of accelerated propagation of relativistic electromagnetic plasma wavepackets","authors":"Felipe A. Asenjo","doi":"10.1063/5.0220386","DOIUrl":"https://doi.org/10.1063/5.0220386","url":null,"abstract":"Relativistic electromagnetic plasma waves are described by a dynamical equation that can be solved not only in terms of plane waves, but also for several different accelerating wavepacket solutions. Depending on the spatial and temporal dependence of the plasma frequency, different kinds of accelerating solutions can be obtained, for example, in terms of Airy or Weber functions. Also, we show that an arbitrary accelerated wavepacket solution is possible, for example, for a system with a luminal plasma slab.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"27 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Self-focusing emerges as a nonlinear optical phenomenon resulting from an intense laser field and plasma interaction. This study investigates the self-focusing behavior of Gaussian laser beams within magnetized plasma environments utilizing a novel approach, source-dependent expansion. By employing source-dependent expansion, we explore the intricate dynamics of laser beam propagation, considering the influence of plasma density and external magnetic fields. The interplay between the beam's Gaussian profile and the self-focusing mechanism through rigorous mathematical analysis and numerical simulations, particularly in the presence of plasma-induced nonlinearities, is elucidated here. Our findings reveal crucial insight into the evolution of laser beams under diverse parameters, including the ponderomotive force, relativistic factors, plasma frequency, polarization states, external magnetic field, wavelength, and laser intensity. This research not only contributes to advancing our fundamental understanding of laser–plasma interactions but also holds promise for optimizing laser-driven applications.
{"title":"Investigation of self-focusing of Gaussian laser beams within magnetized plasma via source-dependent expansion method","authors":"A. A. Molavi Choobini, S. S. Ghaffari-Oskooei","doi":"10.1063/5.0211393","DOIUrl":"https://doi.org/10.1063/5.0211393","url":null,"abstract":"Self-focusing emerges as a nonlinear optical phenomenon resulting from an intense laser field and plasma interaction. This study investigates the self-focusing behavior of Gaussian laser beams within magnetized plasma environments utilizing a novel approach, source-dependent expansion. By employing source-dependent expansion, we explore the intricate dynamics of laser beam propagation, considering the influence of plasma density and external magnetic fields. The interplay between the beam's Gaussian profile and the self-focusing mechanism through rigorous mathematical analysis and numerical simulations, particularly in the presence of plasma-induced nonlinearities, is elucidated here. Our findings reveal crucial insight into the evolution of laser beams under diverse parameters, including the ponderomotive force, relativistic factors, plasma frequency, polarization states, external magnetic field, wavelength, and laser intensity. This research not only contributes to advancing our fundamental understanding of laser–plasma interactions but also holds promise for optimizing laser-driven applications.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"87 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Varela, K. Nagaoka, Y. Takemura, K. Y. Watanabe, K. Ida, M. Yoshinuma, K. Nagasaki, A. Cappa, S. Sharapov, D. A. Spong, L. Garcia, Y. Ghai, J. Ortiz
The aim of the present study is to analyze the effect of the neutral beam current drive (NBCD), thermal plasma density, and NBI operational regime on the stability of pressure gradient-driven modes (PGDM) and Alfvén eigenmodes (AE) in LHD inward-shifted configurations. The stabilization of n/m=1/2 PGDM (n toroidal mode and m poloidal mode) is observed in the discharge 167 800 during the co-NBCD phase. The iota profile evolution measured by motional stark effect diagnostic may indicate the iota profile up-shift caused by the co-NBCD can induce a non-resonant transition of the rational surface 1/2 before the mode stabilization. The evolution of the iota profile and continuum gaps in the discharge 167 805 during the ctr-NBCD phase leads to the stabilization of the AE, caused by the narrowing of the continuum gap as the iota profile down-shift. Opposite stability trends are identified for PGDM and AE stability with respect to the thermal plasma density. A larger thermal plasma density (larger thermal β) further enhances PGDM although the continuum gaps are narrower leading to configurations with stable AEs. The linear stability of AEs is analyzed using the gyro-fluid FAR3d code to reproduce the AE stability trends observed in the experiments with respect to the NBCD and thermal plasma density. The analysis of hypothetical scenarios dedicated to study different NBI operational regimes with respect to EP energy, and β and radial density profiles indicate off-axis NBI operation shows a higher EP β threshold to destabilize AEs compared to on-axis configuration. This is explained by the presence of a TAE gap in the inner plasma region, easily destabilized by an on-axis NBI injection. The control of the NBCD and thermal plasma in the discharge 167 800 shows a transitory stabilization of PGDM and AEs, as well as an improved discharge performance identified by an increment of the neutron fluxes.
{"title":"MHD stability trends and improved performance of LHD inward-shifted configurations: The role of the neutral beam current drive and thermal plasma density","authors":"J. Varela, K. Nagaoka, Y. Takemura, K. Y. Watanabe, K. Ida, M. Yoshinuma, K. Nagasaki, A. Cappa, S. Sharapov, D. A. Spong, L. Garcia, Y. Ghai, J. Ortiz","doi":"10.1063/5.0206400","DOIUrl":"https://doi.org/10.1063/5.0206400","url":null,"abstract":"The aim of the present study is to analyze the effect of the neutral beam current drive (NBCD), thermal plasma density, and NBI operational regime on the stability of pressure gradient-driven modes (PGDM) and Alfvén eigenmodes (AE) in LHD inward-shifted configurations. The stabilization of n/m=1/2 PGDM (n toroidal mode and m poloidal mode) is observed in the discharge 167 800 during the co-NBCD phase. The iota profile evolution measured by motional stark effect diagnostic may indicate the iota profile up-shift caused by the co-NBCD can induce a non-resonant transition of the rational surface 1/2 before the mode stabilization. The evolution of the iota profile and continuum gaps in the discharge 167 805 during the ctr-NBCD phase leads to the stabilization of the AE, caused by the narrowing of the continuum gap as the iota profile down-shift. Opposite stability trends are identified for PGDM and AE stability with respect to the thermal plasma density. A larger thermal plasma density (larger thermal β) further enhances PGDM although the continuum gaps are narrower leading to configurations with stable AEs. The linear stability of AEs is analyzed using the gyro-fluid FAR3d code to reproduce the AE stability trends observed in the experiments with respect to the NBCD and thermal plasma density. The analysis of hypothetical scenarios dedicated to study different NBI operational regimes with respect to EP energy, and β and radial density profiles indicate off-axis NBI operation shows a higher EP β threshold to destabilize AEs compared to on-axis configuration. This is explained by the presence of a TAE gap in the inner plasma region, easily destabilized by an on-axis NBI injection. The control of the NBCD and thermal plasma in the discharge 167 800 shows a transitory stabilization of PGDM and AEs, as well as an improved discharge performance identified by an increment of the neutron fluxes.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"14 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. J. Adrian, R. Bionta, D. Casey, M. Gatu Johnson, S. Kerr, B. Lahmann, C. K. Li, R. Nora, R. D. Petrasso, G. Rigon, D. Schlossberg, F. H. Séguin, J. A. Frenje
The directional energy spectrum of neutrons generated from the in-flight fusion reaction of 1-MeV tritons contains information about the hot-spot symmetry. The National Ignition Facility (NIF) fields Symmetry Capsule (Symcap) implosions, which have historically measured the symmetry of the radiation, drive by measuring the hot-spot shape via x-ray self-emission. Symcaps are used to tune the hot-spot symmetry for ignition experiments at the NIF. This work shows the relationship between directional secondary DT-n spectra and x-ray imaging data for a large database of Symcap implosions. A correlation is observed between the relative widths of the DT-n spectra measured with nTOFs and the shape measured with x-ray imaging. A Monte Carlo model, which computes the directional secondary DT-n spectrum, is used to interpret the results. A comparison of the x-ray and secondary DT-n data with the Monte Carlo model indicates that 56% of the variance between the two datasets is explained by a P2 asymmetry. More advanced simulations using HYDRA suggest that the unaccounted variance is due to P1 and P4 asymmetries present in the hot spot. The comparison of secondary DT-n data and x-ray imaging data to the modeling shows the DT-n data contain important information that supplements current P2 measurements and contain new information about the P1 asymmetry.
1-MeV 三子飞行中聚变反应产生的中子的定向能谱包含热点对称性信息。美国国家点火装置（NIF）的场对称胶囊（Symcap）内爆历来测量辐射的对称性，其驱动方式是通过 X 射线自发射测量热点形状。Symcaps 用于调整 NIF 点火实验的热点对称性。这项工作显示了大型 Symcap 内爆数据库中定向二次 DT-n 光谱与 X 射线成像数据之间的关系。通过 nTOF 测量的 DT-n 光谱相对宽度与 X 射线成像测量的形状之间存在相关性。蒙特卡洛模型可计算定向二次 DT-n 光谱，用于解释结果。将 X 射线和二次 DT-n 数据与蒙特卡罗模型进行比较后发现，两个数据集之间 56% 的差异是由 P2 不对称解释的。使用 HYDRA 进行的更高级模拟表明，未计算的差异是由于热点中存在的 P1 和 P4 不对称造成的。二级 DT-n 数据和 X 射线成像数据与建模的比较表明，DT-n 数据包含补充当前 P2 测量的重要信息，并包含有关 P1 不对称的新信息。
{"title":"Diagnosing hot-spot symmetry in surrogate ignition experiments via secondary DT-neutron spectroscopy at the NIF","authors":"P. J. Adrian, R. Bionta, D. Casey, M. Gatu Johnson, S. Kerr, B. Lahmann, C. K. Li, R. Nora, R. D. Petrasso, G. Rigon, D. Schlossberg, F. H. Séguin, J. A. Frenje","doi":"10.1063/5.0210125","DOIUrl":"https://doi.org/10.1063/5.0210125","url":null,"abstract":"The directional energy spectrum of neutrons generated from the in-flight fusion reaction of 1-MeV tritons contains information about the hot-spot symmetry. The National Ignition Facility (NIF) fields Symmetry Capsule (Symcap) implosions, which have historically measured the symmetry of the radiation, drive by measuring the hot-spot shape via x-ray self-emission. Symcaps are used to tune the hot-spot symmetry for ignition experiments at the NIF. This work shows the relationship between directional secondary DT-n spectra and x-ray imaging data for a large database of Symcap implosions. A correlation is observed between the relative widths of the DT-n spectra measured with nTOFs and the shape measured with x-ray imaging. A Monte Carlo model, which computes the directional secondary DT-n spectrum, is used to interpret the results. A comparison of the x-ray and secondary DT-n data with the Monte Carlo model indicates that 56% of the variance between the two datasets is explained by a P2 asymmetry. More advanced simulations using HYDRA suggest that the unaccounted variance is due to P1 and P4 asymmetries present in the hot spot. The comparison of secondary DT-n data and x-ray imaging data to the modeling shows the DT-n data contain important information that supplements current P2 measurements and contain new information about the P1 asymmetry.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"84 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Février, S. Gorno, C. Theiler, M. Carpita, G. Durr-Legoupil-Nicoud, M. von Allmen
Studying the process of divertor detachment and the associated complex interplay of plasma dynamics and atomic physics processes is of utmost importance for future fusion reactors. While simplified analytical models exist to interpret the general features of detachment, they are limited in their predictive power, and complex two-dimensional (2D) or even three-dimensional (3D) codes are generally required to provide a self-consistent picture of the divertor. As an intermediate step, one-dimensional (1D) models of the scrape-off layer (SOL) can be particularly insightful as the dynamics are greatly simplified, while still self-consistently including various source and sink terms at play, as well as additional important effects such as flows. These codes can be used to shed light on the physics at play, to perform fast parameter scans, or to interpret experiments. In this paper, we introduce the SPLEND1D (Simulator of PLasma ENabling Detachment in 1D) code: a fast and versatile 1D SOL model. We present in detail the model that is implemented in SPLEND1D. We then employ the code to explore various elements of detachment physics for parameters typical of the Tokamak à Configuration Variable, including the atomic physics and other processes behind power and momentum losses, and explore the various hypotheses and free parameters of the model.
研究岔流器脱离过程以及等离子体动力学和原子物理学过程的相关复杂相互作用，对于未来的聚变反应堆至关重要。虽然有简化的分析模型来解释脱离的一般特征，但它们的预测能力有限，通常需要复杂的二维（2D）甚至三维（3D）代码来提供憩室的自洽图像。作为中间步骤，一维（1D）刮除层（SOL）模型尤其具有洞察力，因为其动力学特性已被大大简化，同时仍能自洽地包含各种起作用的源和汇项，以及其他重要效应（如流动）。这些代码可用于揭示发生作用的物理学原理、执行快速参数扫描或解释实验。在本文中，我们将介绍 SPLEND1D（Simulator of PLasma ENabling Detachment in 1D）代码：一种快速、通用的一维 SOL 模型。我们将详细介绍 SPLEND1D 所实现的模型。然后，我们利用该代码探索托卡马克 à 配置变量典型参数的各种脱离物理要素，包括原子物理以及功率和动量损失背后的其他过程，并探索模型的各种假设和自由参数。
{"title":"SPLEND1D, a reduced one-dimensional model to investigate the physics of plasma detachment","authors":"O. Février, S. Gorno, C. Theiler, M. Carpita, G. Durr-Legoupil-Nicoud, M. von Allmen","doi":"10.1063/5.0202986","DOIUrl":"https://doi.org/10.1063/5.0202986","url":null,"abstract":"Studying the process of divertor detachment and the associated complex interplay of plasma dynamics and atomic physics processes is of utmost importance for future fusion reactors. While simplified analytical models exist to interpret the general features of detachment, they are limited in their predictive power, and complex two-dimensional (2D) or even three-dimensional (3D) codes are generally required to provide a self-consistent picture of the divertor. As an intermediate step, one-dimensional (1D) models of the scrape-off layer (SOL) can be particularly insightful as the dynamics are greatly simplified, while still self-consistently including various source and sink terms at play, as well as additional important effects such as flows. These codes can be used to shed light on the physics at play, to perform fast parameter scans, or to interpret experiments. In this paper, we introduce the SPLEND1D (Simulator of PLasma ENabling Detachment in 1D) code: a fast and versatile 1D SOL model. We present in detail the model that is implemented in SPLEND1D. We then employ the code to explore various elements of detachment physics for parameters typical of the Tokamak à Configuration Variable, including the atomic physics and other processes behind power and momentum losses, and explore the various hypotheses and free parameters of the model.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"217 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a transmission model of power-exponential Airy vortex beams in plasma turbulence is established based on the random phase screen theory, and the information transmission characteristics of Airy vortex beams are compared under the OOK, BPSK, and DPSK modulation modes in free-space optical communication systems. Bit error rates (BERs) were calculated for different power indices (n), undulation variances (<Δn2>), transmission distances, and anisotropy parameters. In addition, the orbital angular momentum multiplexing of Airy vortex beams in the Line-of-Sight multiple input multiple output system under a plasma turbulence environment is investigated. The spectral efficiency (SE) is analyzed for different signal-to-noise ratio (SNR) and radii of the emitting surface, and the effects of the variation in the system's numerical aperture and the power exponent on the SE and the effective degrees of freedom in space are analyzed. The results show that the Airy beam has better turbulence resistance than the Laguerre–Gaussian beam. The power-exponential Airy beam has better transmission performance than the conventional Airy beam. By increasing the anisotropy parameter, the BER of the system decreases. When the <Δn2> and the transmission distance increase, the BER increases. Increasing the SNR, the radius of the launching surface and the choice of power-exponential Airy beams can improve the channel capacity. These findings provide a theoretical basis for the problem of optical signal propagation in plasma turbulence.
{"title":"Analysis of communication characteristics of Airy vortex beams in turbulent plasma sheath","authors":"Tingwei Sun, Qingqing Deng, Wei Chen, Yong Bo, Lixia Yang, Lixin Guo","doi":"10.1063/5.0194716","DOIUrl":"https://doi.org/10.1063/5.0194716","url":null,"abstract":"In this paper, a transmission model of power-exponential Airy vortex beams in plasma turbulence is established based on the random phase screen theory, and the information transmission characteristics of Airy vortex beams are compared under the OOK, BPSK, and DPSK modulation modes in free-space optical communication systems. Bit error rates (BERs) were calculated for different power indices (n), undulation variances (&lt;Δn2&gt;), transmission distances, and anisotropy parameters. In addition, the orbital angular momentum multiplexing of Airy vortex beams in the Line-of-Sight multiple input multiple output system under a plasma turbulence environment is investigated. The spectral efficiency (SE) is analyzed for different signal-to-noise ratio (SNR) and radii of the emitting surface, and the effects of the variation in the system's numerical aperture and the power exponent on the SE and the effective degrees of freedom in space are analyzed. The results show that the Airy beam has better turbulence resistance than the Laguerre–Gaussian beam. The power-exponential Airy beam has better transmission performance than the conventional Airy beam. By increasing the anisotropy parameter, the BER of the system decreases. When the &lt;Δn2&gt; and the transmission distance increase, the BER increases. Increasing the SNR, the radius of the launching surface and the choice of power-exponential Airy beams can improve the channel capacity. These findings provide a theoretical basis for the problem of optical signal propagation in plasma turbulence.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"190 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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