论文标题
摩托车和平板ETG ETG不稳定性在射流基座线性光谱中的优势
Toroidal and slab ETG instability dominance in the linear spectrum of JET-ILW pedestals
论文作者
论文摘要
局部线性陀螺仪模拟表明,电子温度梯度(ETG)不稳定性是陡峭梯度区域中$k_yρ_i\ gtrsim的增长最快的模式,用于喷射基座放电(92174),其中电子温度梯度比离子温度梯度陡。在这里,$ k_y $是垂直于磁场和径向方向的方向的波数,而$ρ_i$是离子gyroradius。在$ k_yρ_i\ gtrsim 1 $时,最快的增长模式通常是一种新型的环形ETG不稳定性。此环形ETG模式以尺度驱动到$ k_yρ_i\ sim(ρ_i /ρ_e)l_ {te} / r_0 \ sim 1 $,并且在足够大的径向radial vavenumber中,电子有限的Larmor Radius Radius Radius Radius效果变得很重要;也就是说,$ k_xρ_e\ sim 1 $,其中$ k_x $是有效的径向波数。在这里,$ρ_e$是电子gyroradius,$ r_0 $是最后一个封闭通量表面的主要半径,$ 1/l_ {te} $是与平衡电子温度的对数梯度成正比的反相反长度。生长最快的环形ETG模式通常被驱动到远离舷外平面。在此平衡中,离子温度梯度不稳定性在所有尺度上都是亚辅助性,动力学气球模式被$ \ mathbf {e} \ times \ times \ mathbf {b} $ shear抑制。 ETG模式非常适合$ \ MathBf {E} \ times \ Mathbf {B} $ shear。启发式的准线性论点表明,新型的环形ETG不稳定性对于运输很重要。
Local linear gyrokinetic simulations show that electron temperature gradient (ETG) instabilities are the fastest growing modes for $k_y ρ_i \gtrsim 0.1$ in the steep gradient region for a JET pedestal discharge (92174) where the electron temperature gradient is steeper than the ion temperature gradient. Here, $k_y$ is the wavenumber in the direction perpendicular to both the magnetic field and the radial direction, and $ρ_i$ is the ion gyroradius. At $k_y ρ_i \gtrsim 1$, the fastest growing mode is often a novel type of toroidal ETG instability. This toroidal ETG mode is driven at scales as large as $k_y ρ_i \sim (ρ_i/ρ_e) L_{Te} / R_0 \sim 1$ and at a sufficiently large radial wavenumber that electron finite Larmor radius effects become important; that is, $K_x ρ_e \sim 1$, where $K_x$ is the effective radial wavenumber. Here, $ρ_e$ is the electron gyroradius, $R_0$ is the major radius of the last closed flux surface, and $1/L_{Te}$ is an inverse length proportional to the logarithmic gradient of the equilibrium electron temperature. The fastest growing toroidal ETG modes are often driven far away from the outboard midplane. In this equilibrium, ion temperature gradient instability is subdominant at all scales and kinetic ballooning modes are shown to be suppressed by $\mathbf{ E} \times \mathbf{ B} $ shear. ETG modes are very resilient to $\mathbf{ E} \times \mathbf{ B}$ shear. Heuristic quasilinear arguments suggest that the novel toroidal ETG instability is important for transport.