High-n collisionless ballooning modes in axisymmetric toroidal plasmas

C. Z. Cheng

doi:10.1088/0029-5515/22/6/005

High-n collisionless ballooning modes in axisymmetric toroidal plasmas

C. Z. Cheng

Institute of Space and Plasma Sciences

Research output: Contribution to journal › Article › peer-review

36 Citations (Scopus)

Abstract

A collisionless kinetic ballooning-mode equation which includes the full ion finite-Larmorradius (FLR) the magnetic-drift and the trapped-electron effects is derived and investigated for a largeaspect- ratio circular-flux-surface equilibrium in the frequency regime ω_biω_ti< ω < ω_beω_teThe finite-Larmor-radius effects can reduce the growth rate but do not stabilize the ballooning modes due to the destabilizing influence of the ion-magnetic-drift resonances. It is in general incorrect to simulate the FLR effects by employing the often used FLR-modified MHD model for (k_θρ_i)²≳ 0.1 and ϵ_n≳ 0.1 where k_θρ_iis the ion FLR parameter and ϵ_n= Ln/R measures the magnetic-drift frequency. The trapped electrons have a stabilizing effect due to the reduction of the destabilizing circulating-electron parallel-current perturbation. For a typical tokamak aspect ratio the critical β can be improved by 40%.

Original language	English
Pages (from-to)	773-785
Number of pages	13
Journal	Nuclear Fusion
Volume	22
Issue number	6
DOIs	https://doi.org/10.1088/0029-5515/22/6/005
Publication status	Published - 1982 Jun

All Science Journal Classification (ASJC) codes

Nuclear and High Energy Physics
Condensed Matter Physics

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Cite this

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title = "High-n collisionless ballooning modes in axisymmetric toroidal plasmas",

abstract = "A collisionless kinetic ballooning-mode equation which includes the full ion finite-Larmorradius (FLR) the magnetic-drift and the trapped-electron effects is derived and investigated for a largeaspect- ratio circular-flux-surface equilibrium in the frequency regime ωbiωti< ω < ωbeωteThe finite-Larmor-radius effects can reduce the growth rate but do not stabilize the ballooning modes due to the destabilizing influence of the ion-magnetic-drift resonances. It is in general incorrect to simulate the FLR effects by employing the often used FLR-modified MHD model for (kθρi)2≳ 0.1 and ϵn≳ 0.1 where kθρiis the ion FLR parameter and ϵn= Ln/R measures the magnetic-drift frequency. The trapped electrons have a stabilizing effect due to the reduction of the destabilizing circulating-electron parallel-current perturbation. For a typical tokamak aspect ratio the critical β can be improved by 40\%.",

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T1 - High-n collisionless ballooning modes in axisymmetric toroidal plasmas

AU - Cheng, C. Z.

PY - 1982/6

Y1 - 1982/6

N2 - A collisionless kinetic ballooning-mode equation which includes the full ion finite-Larmorradius (FLR) the magnetic-drift and the trapped-electron effects is derived and investigated for a largeaspect- ratio circular-flux-surface equilibrium in the frequency regime ωbiωti< ω < ωbeωteThe finite-Larmor-radius effects can reduce the growth rate but do not stabilize the ballooning modes due to the destabilizing influence of the ion-magnetic-drift resonances. It is in general incorrect to simulate the FLR effects by employing the often used FLR-modified MHD model for (kθρi)2≳ 0.1 and ϵn≳ 0.1 where kθρiis the ion FLR parameter and ϵn= Ln/R measures the magnetic-drift frequency. The trapped electrons have a stabilizing effect due to the reduction of the destabilizing circulating-electron parallel-current perturbation. For a typical tokamak aspect ratio the critical β can be improved by 40%.

AB - A collisionless kinetic ballooning-mode equation which includes the full ion finite-Larmorradius (FLR) the magnetic-drift and the trapped-electron effects is derived and investigated for a largeaspect- ratio circular-flux-surface equilibrium in the frequency regime ωbiωti< ω < ωbeωteThe finite-Larmor-radius effects can reduce the growth rate but do not stabilize the ballooning modes due to the destabilizing influence of the ion-magnetic-drift resonances. It is in general incorrect to simulate the FLR effects by employing the often used FLR-modified MHD model for (kθρi)2≳ 0.1 and ϵn≳ 0.1 where kθρiis the ion FLR parameter and ϵn= Ln/R measures the magnetic-drift frequency. The trapped electrons have a stabilizing effect due to the reduction of the destabilizing circulating-electron parallel-current perturbation. For a typical tokamak aspect ratio the critical β can be improved by 40%.

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JO - Nuclear Fusion

JF - Nuclear Fusion

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High-n collisionless ballooning modes in axisymmetric toroidal plasmas

Abstract

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