A new mechanisms for damping of slow magnetosonic waves (SMW) by pressure induced oscillations of the ionization degree is proposed. An explicit formula for the damping rate is quantitatively derived. Physical conditions where the new mechanism will dominate are briefly discussed. The ionization-recombination damping is frequency independent and has no hydrodynamic interpretation. Roughly speaking large area of partially ionized plasma are damper for basses of SMW while usual MHD mechanisms operate as a low pass filter. The derived damping rate is proportional to the square of the sine between the constant magnetic field and the wave-vector. Angular distribution of the spectral density of SMW and Alfven waves (AW) created by turbulent regions and passing through large regions of partially ionized plasma is qualitatively considered. The calculated damping rate is expressed by the electron impact cross section of the hydrogen atom and in short all details of the proposed damping mechanisms are well studied.
{"title":"Slow magnetosonic wave absorption by pressure induced ionization–recombination dissipation","authors":"T. Mishonov, A. Varonov","doi":"10.1063/5.0013983","DOIUrl":"https://doi.org/10.1063/5.0013983","url":null,"abstract":"A new mechanisms for damping of slow magnetosonic waves (SMW) by pressure induced oscillations of the ionization degree is proposed. An explicit formula for the damping rate is quantitatively derived. Physical conditions where the new mechanism will dominate are briefly discussed. The ionization-recombination damping is frequency independent and has no hydrodynamic interpretation. Roughly speaking large area of partially ionized plasma are damper for basses of SMW while usual MHD mechanisms operate as a low pass filter. The derived damping rate is proportional to the square of the sine between the constant magnetic field and the wave-vector. Angular distribution of the spectral density of SMW and Alfven waves (AW) created by turbulent regions and passing through large regions of partially ionized plasma is qualitatively considered. The calculated damping rate is expressed by the electron impact cross section of the hydrogen atom and in short all details of the proposed damping mechanisms are well studied.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76243937","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}
Using high-resolution, two-dimensional particle-in-cell simulations, we investigate numerically the mechanisms of terahertz (THz) emissions in submicron-thick carbon solid foils driven by ultraintense ($sim 10^{20},rm W,cm^{-2}$), ultrashort ($30,rm fs$) laser pulses at normal incidence. The considered range of target thicknesses extends down to the relativistic transparency regime that is known to optimize ion acceleration by femtosecond laser pulses. By disentangling the fields emitted by longitudinal and transverse currents, our analysis reveals that, within the first picosecond after the interaction, THz emission occurs in bursts as a result of coherent transition radiation by the recirculating hot electrons and antenna-type emission by the shielding electron currents traveling along the fast-expanding target surfaces.
{"title":"Terahertz emission from submicron solid targets irradiated by ultraintense femtosecond laser pulses","authors":"J. Déchard, X. Davoine, L. Gremillet, L. Bergé","doi":"10.1063/5.0013415","DOIUrl":"https://doi.org/10.1063/5.0013415","url":null,"abstract":"Using high-resolution, two-dimensional particle-in-cell simulations, we investigate numerically the mechanisms of terahertz (THz) emissions in submicron-thick carbon solid foils driven by ultraintense ($sim 10^{20},rm W,cm^{-2}$), ultrashort ($30,rm fs$) laser pulses at normal incidence. The considered range of target thicknesses extends down to the relativistic transparency regime that is known to optimize ion acceleration by femtosecond laser pulses. By disentangling the fields emitted by longitudinal and transverse currents, our analysis reveals that, within the first picosecond after the interaction, THz emission occurs in bursts as a result of coherent transition radiation by the recirculating hot electrons and antenna-type emission by the shielding electron currents traveling along the fast-expanding target surfaces.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79358419","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}
E. Uchava, A. Tevzadze, B. Shergelashvili, N. S. Dzhalilov, S. Poedts
We study the effects of heat flows and velocity shear on the parallel firehose instability in weakly collisional plasma flow. For this purpose we apply an anisotropic 16-moments MHD fluid closure model that takes into account the pressure and temperature anisotropy, as well as the effect of anisotropic heat flux. The linear stability analysis of the firehose modes is carried out in the incompressible limit, where the MHD flow is parallel to the background magnetic field, while the velocity is sheared in the direction transverse to the flow direction. It seems that an increase of the velocity shear parameter leads to higher growth rates of the firehose instability. The increase of the instability growth rate is most profound for perturbations with oblique wave-numbers $k_{perp}/k_{parallel} < 1$. The heat flux parameter introduces an asymmetry of the instability growth in the shear plane: perturbations with wave-vectors with a component in the direction of the velocity shear grow significantly stronger as compared to those with components in the opposite direction. We discuss the implications of the presented study on the observable features of the solar wind and possible measurements of local parameters of the solar wind based on the stability constraints set by the firehose instability.
{"title":"Fire-hose instability of inhomogeneous plasma flows with heat fluxes","authors":"E. Uchava, A. Tevzadze, B. Shergelashvili, N. S. Dzhalilov, S. Poedts","doi":"10.1063/5.0013490","DOIUrl":"https://doi.org/10.1063/5.0013490","url":null,"abstract":"We study the effects of heat flows and velocity shear on the parallel firehose instability in weakly collisional plasma flow. For this purpose we apply an anisotropic 16-moments MHD fluid closure model that takes into account the pressure and temperature anisotropy, as well as the effect of anisotropic heat flux. The linear stability analysis of the firehose modes is carried out in the incompressible limit, where the MHD flow is parallel to the background magnetic field, while the velocity is sheared in the direction transverse to the flow direction. It seems that an increase of the velocity shear parameter leads to higher growth rates of the firehose instability. The increase of the instability growth rate is most profound for perturbations with oblique wave-numbers $k_{perp}/k_{parallel} < 1$. The heat flux parameter introduces an asymmetry of the instability growth in the shear plane: perturbations with wave-vectors with a component in the direction of the velocity shear grow significantly stronger as compared to those with components in the opposite direction. We discuss the implications of the presented study on the observable features of the solar wind and possible measurements of local parameters of the solar wind based on the stability constraints set by the firehose instability.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86212571","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}
In this paper, we study the constraints imposed by the invariants (generalized helicities and energy) of extended magnetohydrodynamics on some global characteristics of turbulence. We show that the global turbulent kinetic and magnetic energies will approach equipartition only under certain circumstances that depend on the ratio of the generalized helicities. In systems with minimal thermal energy, we demonstrate that the three invariants collectively determine the characteristic length scale associated with Alfvenic turbulence.
{"title":"Constraining Alfvénic turbulence with helicity invariants","authors":"S. Mahajan, M. Lingam","doi":"10.1093/mnras/staa1318","DOIUrl":"https://doi.org/10.1093/mnras/staa1318","url":null,"abstract":"In this paper, we study the constraints imposed by the invariants (generalized helicities and energy) of extended magnetohydrodynamics on some global characteristics of turbulence. We show that the global turbulent kinetic and magnetic energies will approach equipartition only under certain circumstances that depend on the ratio of the generalized helicities. In systems with minimal thermal energy, we demonstrate that the three invariants collectively determine the characteristic length scale associated with Alfvenic turbulence.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86947686","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 space-filter approach has proved a fundamental tool in studying turbulence in neutral fluids, providing the ability to analyze scale-to-scale energy transfer in configuration space. It is well known that turbulence in plasma presents challenges different from neutral fluids, especially when the scale of interests include kinetic effects. The space-filter approach is still largely unexplored for kinetic plasma. Here we derive the space-filtered (or, equivalently "coarse-grained") equations in configuration space for a quasi-neutral hybrid-kinetic plasma model, in which ions are fully kinetic and electrons are a neutralizing fluid. Different models and closures for the electron fluid are considered, including finite electron-inertia effects and full electrons' pressure-tensor dynamics. Implications for the cascade of turbulent fluctuations in real space depending on different approximations are discussed.
{"title":"Space-filter techniques for quasi-neutral hybrid-kinetic models","authors":"S. Cerri, Enrico Camporeale","doi":"10.1063/5.0012924","DOIUrl":"https://doi.org/10.1063/5.0012924","url":null,"abstract":"The space-filter approach has proved a fundamental tool in studying turbulence in neutral fluids, providing the ability to analyze scale-to-scale energy transfer in configuration space. It is well known that turbulence in plasma presents challenges different from neutral fluids, especially when the scale of interests include kinetic effects. The space-filter approach is still largely unexplored for kinetic plasma. Here we derive the space-filtered (or, equivalently \"coarse-grained\") equations in configuration space for a quasi-neutral hybrid-kinetic plasma model, in which ions are fully kinetic and electrons are a neutralizing fluid. Different models and closures for the electron fluid are considered, including finite electron-inertia effects and full electrons' pressure-tensor dynamics. Implications for the cascade of turbulent fluctuations in real space depending on different approximations are discussed.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76013493","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}
During tokamak disruptions the profile of the net parallel current is observed to flatten on a time scale that is so fast that it must be due to a fast magnetic reconnection. After a fast magnetic reconnection has broken magnetic surfaces, a single magnetic field line covers an entire volume and not just a magnetic surface. The current profile, given by $Kequivmu_0j_{||}/B$, relaxes to a constant within that volume by Alfven waves propagating along the chaotic magnetic field lines. The time scale for this relaxation determines the commonly observed disruption phenomena of a current spike and a sudden drop in the plasma internal inductance. An efficient method for studying this relaxation is derived, which allows a better understanding of the information encoded in the current spike and the associated sudden drop in the plasma internal inductance. Implications for coronal heating are also discussed.
{"title":"Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar corona","authors":"A. Boozer","doi":"10.1063/5.0014107","DOIUrl":"https://doi.org/10.1063/5.0014107","url":null,"abstract":"During tokamak disruptions the profile of the net parallel current is observed to flatten on a time scale that is so fast that it must be due to a fast magnetic reconnection. After a fast magnetic reconnection has broken magnetic surfaces, a single magnetic field line covers an entire volume and not just a magnetic surface. The current profile, given by $Kequivmu_0j_{||}/B$, relaxes to a constant within that volume by Alfven waves propagating along the chaotic magnetic field lines. The time scale for this relaxation determines the commonly observed disruption phenomena of a current spike and a sudden drop in the plasma internal inductance. An efficient method for studying this relaxation is derived, which allows a better understanding of the information encoded in the current spike and the associated sudden drop in the plasma internal inductance. Implications for coronal heating are also discussed.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87656953","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}
T. Blackburn, A. Macleod, A. Ilderton, B. King, Suo Tang, Mattias Marklund
Electrons at the surface of a plasma that is irradiated by a laser with intensity in excess of $10^{23}~mathrm{W}mathrm{cm}^{-2}$ are accelerated so strongly that they emit bursts of synchrotron radiation. Although the combination of high photon and electron density and electromagnetic field strength at the plasma surface makes particle-particle interactions possible, these interactions are usually neglected in simulations of the high-intensity regime. Here we demonstrate an implementation of two such processes: photon absorption and stimulated emission. We show that, for plasmas that are opaque to the laser light, photon absorption would cause complete depletion of the multi-keV region of the synchrotron photon spectrum, unless compensated by stimulated emission. Our results motivate further study of the density dependence of QED phenomena in strong electromagnetic fields.
{"title":"Self-absorption of synchrotron radiation in a laser-irradiated plasma","authors":"T. Blackburn, A. Macleod, A. Ilderton, B. King, Suo Tang, Mattias Marklund","doi":"10.1063/5.0044766","DOIUrl":"https://doi.org/10.1063/5.0044766","url":null,"abstract":"Electrons at the surface of a plasma that is irradiated by a laser with intensity in excess of $10^{23}~mathrm{W}mathrm{cm}^{-2}$ are accelerated so strongly that they emit bursts of synchrotron radiation. Although the combination of high photon and electron density and electromagnetic field strength at the plasma surface makes particle-particle interactions possible, these interactions are usually neglected in simulations of the high-intensity regime. Here we demonstrate an implementation of two such processes: photon absorption and stimulated emission. We show that, for plasmas that are opaque to the laser light, photon absorption would cause complete depletion of the multi-keV region of the synchrotron photon spectrum, unless compensated by stimulated emission. Our results motivate further study of the density dependence of QED phenomena in strong electromagnetic fields.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85265506","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}
Pub Date : 2020-04-28DOI: 10.1103/PHYSREVRESEARCH.2.033233
K. Schoeffler, L. Silva
The expansion of plasma with non-parallel temperature and density gradients, and the generation of magnetic field via the Biermann battery is modeled using particle-in-cell simulations that include collisional effects via Monte Carlo methods. A scaling of the degree of collisionality shows that an anisotropy can be produced, and drive the Weibel instability, for gradient scales shorter than the mean free path. For larger collision rates, the Biermann battery dominates as the cause of magnetic field generation. When the most energetic particles remain collisionless, the Nernst effect causes the Biermann field to be dragged with the heat flux, piled up, and enhanced.
{"title":"Effects of collisions on the generation and suppression of temperature anisotropies and the Weibel instability","authors":"K. Schoeffler, L. Silva","doi":"10.1103/PHYSREVRESEARCH.2.033233","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.2.033233","url":null,"abstract":"The expansion of plasma with non-parallel temperature and density gradients, and the generation of magnetic field via the Biermann battery is modeled using particle-in-cell simulations that include collisional effects via Monte Carlo methods. A scaling of the degree of collisionality shows that an anisotropy can be produced, and drive the Weibel instability, for gradient scales shorter than the mean free path. For larger collision rates, the Biermann battery dominates as the cause of magnetic field generation. When the most energetic particles remain collisionless, the Nernst effect causes the Biermann field to be dragged with the heat flux, piled up, and enhanced.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81205618","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 stability theory of the inductively coupled plasma (ICP) is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. The theory predicts the existence the instabilities of the ICP which are driven by the current formed in the skin layer by the accelerated electrons, which move relative ions under the action of the ponderomotive force.
{"title":"The ion-acoustic instability of the inductively coupled plasma driven by the ponderomotive electron current formed in the skin layer","authors":"V. Mikhailenko, V. Mikhailenko, H. J. Lee","doi":"10.1063/1.5144472","DOIUrl":"https://doi.org/10.1063/1.5144472","url":null,"abstract":"The stability theory of the inductively coupled plasma (ICP) is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. The theory predicts the existence the instabilities of the ICP which are driven by the current formed in the skin layer by the accelerated electrons, which move relative ions under the action of the ponderomotive force.","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86536746","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}
Tomáš Odstrčil, N. Howard, F. Sciortino, C. Chrystal, C. Holland, E. Hollmann, G. McKee, K. Thome, T. Wilks
Laser blow-off injections of aluminum and tungsten have been performed on the DIII-D tokamak to investigate the variation of impurity transport in a set of dedicated ion and electron heating scans with a fixed value of the external torque. The particle transport is quantified via the Bayesian inference method, which, constrained by a combination of a charge exchange recombination spectroscopy, soft X-ray measurements, and VUV spectroscopy provides a detailed uncertainty quantification of the transport coefficients. Contrasting discharge phases with a dominant electron and ion heating reveal a factor of 30 increase in midradius impurity diffusion and a 3-fold drop in the impurity confinement time when additional electron heating is applied. Further, the calculated stationary aluminum density profiles reverse from peaked in electron heated to hollow in the ion heated case, following a similar trend as electron and carbon density profiles. Comparable values of a core diffusion have been observed for W and Al ions, while differences in the propagation dynamics of these impurities are attributed to pedestal and edge transport. Modeling of the core transport with non-linear gyrokinetics code CGYRO [J. Candy and E. Belly J. Comput. Phys. 324,73 (2016)], significantly underpredicts the magnitude of the variation in Al transport. The experiment demonstrates a 3-times steeper increase of impurity diffusion with additional electron heat flux and 10-times lower diffusion in ion heated case than predicted by the modeling. However, the CGYRO model correctly predicts that the Al diffusion dramatically increases below the linear threshold for the transition from the ion temperature gradient (ITG) to trapped electron mode (TEM).
在DIII-D托卡马克上进行了铝和钨的激光吹脱注射，研究了在固定的外转矩下，一组专用离子和电子加热扫描中杂质输运的变化。粒子输运通过贝叶斯推理方法进行量化，该方法在电荷交换复合光谱、软x射线测量和VUV光谱的组合约束下，提供了输运系数的详细不确定度量化。对比以电子和离子加热为主的放电相，发现当附加电子加热时，中半径杂质扩散增加了30倍，杂质约束时间减少了3倍。此外，计算的固定铝密度曲线从电子加热时的峰值到离子加热时的中空，遵循与电子和碳密度曲线相似的趋势。已经观察到W和Al离子的核心扩散值相当，而这些杂质的传播动力学差异归因于基座和边缘输运。基于非线性陀螺动力学代码CGYRO的岩心输运建模[J]。Candy和E. Belly J. Comput。物理学报，324,73(2016)]，明显低估了铝转运的变化幅度。实验表明，与模型预测相比，在电子热流增加的情况下，杂质扩散速度增加了3倍，而在离子加热情况下，杂质扩散速度降低了10倍。然而，CGYRO模型正确地预测了从离子温度梯度(ITG)到捕获电子模式(TEM)转变的线性阈值以下Al扩散急剧增加。
{"title":"Dependence of the impurity transport on the dominant turbulent regime in ELM-y H-mode discharges on the DIII-D tokamak","authors":"Tomáš Odstrčil, N. Howard, F. Sciortino, C. Chrystal, C. Holland, E. Hollmann, G. McKee, K. Thome, T. Wilks","doi":"10.1063/5.0010725","DOIUrl":"https://doi.org/10.1063/5.0010725","url":null,"abstract":"Laser blow-off injections of aluminum and tungsten have been performed on the DIII-D tokamak to investigate the variation of impurity transport in a set of dedicated ion and electron heating scans with a fixed value of the external torque. The particle transport is quantified via the Bayesian inference method, which, constrained by a combination of a charge exchange recombination spectroscopy, soft X-ray measurements, and VUV spectroscopy provides a detailed uncertainty quantification of the transport coefficients. Contrasting discharge phases with a dominant electron and ion heating reveal a factor of 30 increase in midradius impurity diffusion and a 3-fold drop in the impurity confinement time when additional electron heating is applied. Further, the calculated stationary aluminum density profiles reverse from peaked in electron heated to hollow in the ion heated case, following a similar trend as electron and carbon density profiles. Comparable values of a core diffusion have been observed for W and Al ions, while differences in the propagation dynamics of these impurities are attributed to pedestal and edge transport. Modeling of the core transport with non-linear gyrokinetics code CGYRO [J. Candy and E. Belly J. Comput. Phys. 324,73 (2016)], significantly underpredicts the magnitude of the variation in Al transport. The experiment demonstrates a 3-times steeper increase of impurity diffusion with additional electron heat flux and 10-times lower diffusion in ion heated case than predicted by the modeling. However, the CGYRO model correctly predicts that the Al diffusion dramatically increases below the linear threshold for the transition from the ion temperature gradient (ITG) to trapped electron mode (TEM).","PeriodicalId":8461,"journal":{"name":"arXiv: Plasma Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90564819","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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