University of California, Los Angeles, Los Angeles, California 90024, USA.
Phys Rev Lett. 2013 Jun 28;110(26):265001. doi: 10.1103/PhysRevLett.110.265001. Epub 2013 Jun 24.
Experiments are performed at the Enormous Toroidal Plasma Device at UCLA to study the neutral boundary layer (NBL) between a magnetized plasma and a neutral gas along the direction of a confining magnetic field. This is the first experiment to measure plasma termination within a neutral gas without the presence of a wall or obstacle. A magnetized, current-free helium plasma created by a lanthanum hexaboride (LaB6) cathode terminates entirely within a neutral helium gas. The plasma is weakly ionized (ne/nn∼1%) and collisional λn≪Lplasma}. The NBL occurs where the plasma pressure equilibrates with the neutral gas pressure, consistent with a pressure balance model. It is characterized by a field-aligned ambipolar electric field, developing self-consistently to maintain a current-free termination of the plasma on the neutral gas. Probes are inserted into the plasma to measure the plasma density, flow, temperature, current, and potential. These measurements confirm the presence of the ambipolar field and the pressure equilibration model of the NBL.
在加州大学洛杉矶分校的巨大环形容量等离子体装置中进行了实验，以研究沿着约束磁场方向的磁化等离子体和中性气体之间的中性边界层（NBL）。这是第一个在没有壁或障碍物存在的情况下测量中性气体内部等离子体终止的实验。由镧六硼化物（LaB6）阴极产生的磁化、无电流氦等离子体完全终止于中性氦气体中。等离子体是弱电离的（ne/nn∼1%），碰撞λn≪Lplasma}。NBL 发生在等离子体压力与中性气体压力平衡的地方，与压力平衡模型一致。它的特点是场向的双极电场，自洽地发展以维持等离子体在中性气体上的无电流终止。探针被插入等离子体中以测量等离子体密度、流动、温度、电流和电位。这些测量证实了双极场和 NBL 的压力平衡模型的存在。
