arXiv: Plasma Physics最新文献

Kinetic simulation of electron cyclotron resonance assisted gas breakdown in split-biased waveguides for ITER collective Thomson scattering diagnostic 裂变偏置波导中电子回旋共振辅助气体击穿的动力学模拟

arXiv: Plasma Physics Pub Date : 2021-04-29 DOI: 10.1063/5.0055461

J. Trieschmann, A. W. Larsen, T. Mussenbrock, S. Korsholm

{"title":"Kinetic simulation of electron cyclotron resonance assisted gas breakdown in split-biased waveguides for ITER collective Thomson scattering diagnostic","authors":"J. Trieschmann, A. W. Larsen, T. Mussenbrock, S. Korsholm","doi":"10.1063/5.0055461","DOIUrl":"https://doi.org/10.1063/5.0055461","url":null,"abstract":"For the measurement of the dynamics of fusion-born alpha particles $E_alpha leq 3.5$ MeV in ITER using collective Thomson scattering (CTS), safe transmission of a gyrotron beam at mm-wavelength (1 MW, 60 GHz) passing the electron cyclotron resonance (ECR) in the in-vessel tokamak `port plug' vacuum is a prerequisite. Depending on neutral gas pressure and composition, ECR-assisted gas breakdown may occur at the location of the resonance, which must be mitigated for diagnostic performance and safety reasons. The concept of a split electrically biased waveguide (SBWG) has been previously demonstrated in [C.P. Moeller, U.S. Patent 4,687,616 (1987)]. The waveguide is longitudinally split and a kV bias voltage applied between the two halves. Electrons are rapidly removed from the central region of high radio frequency electric field strength, mitigating breakdown. As a full scale experimental investigation of gas and electromagnetic field conditions inside the ITER equatorial port plugs is currently unattainable, a corresponding Monte Carlo simulation study is presented. Validity of the Monte Carlo electron model is demonstrated with a prediction of ECR breakdown and the mitigation pressure limits for the above quoted reference case with $^1$H$_2$ (and pollutant high $Z$ elements). For the proposed ITER CTS design with a 88.9 mm inner diameter SBWG, ECR breakdown is predicted to occur down to a pure $^1$H$_2$ pressure of 0.3 Pa, while mitigation is shown to be effective at least up to 10 Pa using a bias voltage of 1 kV. The analysis is complemented by results for relevant electric/magnetic field arrangements and limitations of the SBWG mitigation concept are addressed.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83872807","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}

引用次数: 1

Topological phases, topological phase transition, and bulk-edge correspondence of magnetized cold plasmas 磁化冷等离子体的拓扑相、拓扑相变和体边对应

arXiv: Plasma Physics Pub Date : 2021-03-04 DOI: 10.21203/RS.3.RS-279306/V1

Yichen Fu, H. Qin

引用次数: 1

Non-Maxwellianity of electron distributions near Earth's magnetopause 地球磁层顶附近电子分布的非麦克斯韦性

arXiv: Plasma Physics Pub Date : 2021-02-19 DOI: 10.1002/ESSOAR.10506282.1

D. Graham, Y. Khotyaintsev, M. André, A. Vaivads, A. Chasapis, W. Matthaeus, A. Retinò, F. Valentini, D. Gershman

引用次数: 3

Theory of Plasma-Cascade Instability 等离子体级联不稳定性理论

arXiv: Plasma Physics Pub Date : 2021-01-11 DOI: 10.2172/1760645

V. Litvinenko, Gang Wang

引用次数: 1

Ion cyclotron parametric turbulence and anomalous convective transport of the inhomogeneous plasma in front of the fast wave antenna 快波天线前非均匀等离子体的离子回旋加速器参数湍流和异常对流输运

arXiv: Plasma Physics Pub Date : 2020-12-17 DOI: 10.1063/5.0040946

V. Mikhailenko, V. Mikhailenko, H. Lee

引用次数: 3

Efficacy of the radial pair potential approximation for molecular dynamics simulations of dense plasmas 致密等离子体分子动力学模拟中径向对势近似的有效性

arXiv: Plasma Physics Pub Date : 2020-12-11 DOI: 10.1063/5.0040062

L. Stanek, R. Clay, M. Dharma-wardana, M. Wood, K. Beckwith, M. Murillo

引用次数: 12

Magnetic field transport in propagating thermonuclear burn 热核燃烧传播过程中的磁场输运

arXiv: Plasma Physics Pub Date : 2020-12-09 DOI: 10.1063/5.0040161

B. Appelbe, A. Velikovich, M. Sherlock, C. Walsh, A. Crilly, S. O' Neill, J. Chittenden

引用次数: 7

Ultra-short pulse generation from mid-IR to THz range using plasma wakes and relativistic ionization fronts 利用等离子体尾迹和相对论电离锋产生中红外到太赫兹范围的超短脉冲

arXiv: Plasma Physics Pub Date : 2020-12-02 DOI: 10.1063/5.0039301

Z. Nie, Yipeng Wu, Chaojie Zhang, W. Mori, C. Joshi, W. Lu, C. Pai, J. Hua, Jyhpyng Wang

{"title":"Ultra-short pulse generation from mid-IR to THz range using plasma wakes and relativistic ionization fronts","authors":"Z. Nie, Yipeng Wu, Chaojie Zhang, W. Mori, C. Joshi, W. Lu, C. Pai, J. Hua, Jyhpyng Wang","doi":"10.1063/5.0039301","DOIUrl":"https://doi.org/10.1063/5.0039301","url":null,"abstract":"This paper discusses numerical and experimental results on frequency downshifting and upshifting of a 10 $mu$m infrared laser to cover the entire wavelength (frequency) range from $lambda$=1-150 $mu$m ($nu$=300-2 THz) using two different plasma techniques. The first plasma technique utilizes frequency downshifting of the drive laser pulse in a nonlinear plasma wake. Based on this technique, we have proposed and demonstrated that in a tailored plasma structure multi-millijoule energy, single-cycle, long-wavelength IR (3-20 $mu$m) pulses can be generated by using an 810 nm Ti:sapphire drive laser. Here we extend this idea to the THz frequency regime. We show that sub-joule, terawatts, single-cycle terahertz (2-12 THz, or 150-25 $mu$m) pulses can be generated by replacing the drive laser with a picosecond 10 $mu$m CO$_2$ laser and a different shaped plasma structure. The second plasma technique employs frequency upshifting by colliding a CO$_2$ laser with a rather sharp relativistic ionization front created by ionization of a gas in less than half cycle (17 fs) of the CO$_2$ laser. Even though the electrons in the ionization front carry no energy, the frequency of the CO$_2$ laser can be upshifted due to the relativistic Doppler effect as the CO$_2$ laser pulse enters the front. The wavelength can be tuned from 1-10 $mu$m by simply changing the electron density of the front. While the upshifted light with $5 <lambda(mu$m$)< 10$ propagates in the forward direction, that with $1 <lambda(mu$m$)< 5$ is back-reflected. These two plasma techniques seem extremely promising for covering the entire molecular fingerprint region.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74693848","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}

引用次数: 4

Predominant contribution of direct laser acceleration to high-energy electron spectra in a low-density self-modulated laser wakefield accelerator 低密度自调制尾流场加速器中直接激光加速对高能电子能谱的主要贡献

arXiv: Plasma Physics Pub Date : 2020-12-02 DOI: 10.1103/PHYSREVACCELBEAMS.24.011302

P. King, K. Miller, N. Lemos, J. Shaw, B. Frances Kraus, M. Thibodeau, B. Hegelich, J. Hinojosa, P. Michel, C. Joshi, K. Marsh, W. Mori, A. Pak, A. Thomas, F. Albert

{"title":"Predominant contribution of direct laser acceleration to high-energy electron spectra in a low-density self-modulated laser wakefield accelerator","authors":"P. King, K. Miller, N. Lemos, J. Shaw, B. Frances Kraus, M. Thibodeau, B. Hegelich, J. Hinojosa, P. Michel, C. Joshi, K. Marsh, W. Mori, A. Pak, A. Thomas, F. Albert","doi":"10.1103/PHYSREVACCELBEAMS.24.011302","DOIUrl":"https://doi.org/10.1103/PHYSREVACCELBEAMS.24.011302","url":null,"abstract":"The two-temperature relativistic electron spectrum from a low-density ($3times10^{17}$~cm$^{-3}$) self-modulated laser wakefield accelerator (SM-LWFA) is observed to transition between temperatures of $19pm0.65$ and $46pm2.45$ MeV at an electron energy of about 100 MeV. When the electrons are dispersed orthogonally to the laser polarization, their spectrum above 60 MeV shows a forking structure characteristic of direct laser acceleration (DLA). Both the two-temperature distribution and the forking structure are reproduced in a quasi-3D textsc{Osiris} simulation of the interaction of the 1-ps, moderate-amplitude ($a_{0}=2.7$) laser pulse with the low-density plasma. Particle tracking shows that while the SM-LWFA mechanism dominates below 40 MeV, the highest-energy ($>60$ MeV) electrons gain most of their energy through DLA. By separating the simulated electric fields into modes, the DLA-dominated electrons are shown to lose significant energy to the longitudinal laser field from the tight focusing geometry, resulting in a more accurate measure of net DLA energy gain than previously possible.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91454911","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}

引用次数: 3

Electron Beam Chirp Dexterity in Staging Laser Wake Field Acceleration 电子束啁啾灵巧性在激光尾迹场加速中的应用

arXiv: Plasma Physics Pub Date : 2020-11-30 DOI: 10.1063/5.0040897

N. Pathak, A. Zhidkov, T. Hosokai

引用次数: 2