Plasma Heating due to Cyclic Diffusion across a Separatrix
Plasma Heating due to Cyclic Diffusion across a Separatrix
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由于跨分界线的循环扩散而产生等离子体加热
DOI：
10.1103/physrevlett.123.105002
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发表时间：
2019
影响因子：
8.6
通讯作者：
Driscoll, C. F.
中科院分区：
文献类型：
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作者：
Anderegg, F.;Affolter, M.;Dubin, D. H. E.;Driscoll, C. F.
当彭宁-马尔姆伯格陷阱中的镁离子柱被循环地来回推动穿过部分捕获势垒时，我们观察到由于穿过分界线的碰撞扩散而产生的等离子体加热。该势垒是外部施加的轴对称“挤压”势，它在捕获的粒子和通过的粒子之间创建速度分界线。弱的离子-离子碰撞会导致分界线交叉，从而导致不可逆的加热。加热速率与振荡速率乘以碰撞频率的平方根成正比，因此对于低碰撞性等离子体来说可以占主导地位。粒子速度分布函数是用相干激光诱导荧光测量的，并显示通过和捕获的粒子对强制等离子体振荡具有异相响应。
We observe plasma heating due to collisional diffusion across a separatrix when a magnesium ion column in a Penning-Malmberg trap is cyclically pushed back and forth across a partial trapping barrier. The barrier is an externally applied axisymmetric “squeeze” potential, which creates a velocity separatrix between trapped and passing particles. Weak ion-ion collisions then cause separatrix crossings, leading to irreversible heating. The heating rate scales as the square root of the oscillation rate times the collision frequency and thus can be dominant for low-collisionality plasmas. The particle velocity distribution function is measured with coherent laser induced fluorescence and shows passing and trapped particles having an out-of-phase response to the forced plasma oscillations.