Bierwage Andreas, Aiba Nobuyuki, Shinohara Kouji
Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212, Japan.
Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan.
Phys Rev Lett. 2015 Jan 9;114(1):015002. doi: 10.1103/PhysRevLett.114.015002.
When the plasma beta (ratio of thermal to magnetic pressure) in the core of a tokamak is raised to values of several percent, as required for a thermonuclear fusion reactor, continuous spectra of long-wavelength slow magnetosonic waves enter the frequency band occupied by continuous spectra of shear Alfvén waves. It is found that these two branches can couple strongly, so that Alfvén modes that are resonantly driven by suprathermal ions transfer some of their energy to sound waves. Since sound waves are heavily damped by thermal ion Landau resonances, these results reveal a new energy channel that contributes to the damping of Alfvénic instabilities and the noncollisional heating of bulk ions, with potentially important consequences for confinement and fusion performance.
当托卡马克核心处的等离子体β值（热压力与磁压力之比）提高到热核聚变反应堆所需的百分之几的值时，长波长慢磁声波的连续谱进入了剪切阿尔文波连续谱所占据的频带。研究发现，这两个分支可以强烈耦合，使得由超热离子共振驱动的阿尔文模将其部分能量转移到声波上。由于声波会因热离子朗道共振而受到严重阻尼，这些结果揭示了一个新的能量通道，该通道有助于阿尔文不稳定性的阻尼和体离子的非碰撞加热，对约束和聚变性能可能产生重要影响。
