Gorman G M, Warrens M K, Bradshaw S J, Killian T C
Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
Phys Rev Lett. 2021 Feb 26;126(8):085002. doi: 10.1103/PhysRevLett.126.085002.
We demonstrate magnetic confinement of an ultracold neutral plasma (UCNP) created at the null of a biconic cusp, or quadrupole magnetic field. Initially, the UCNP expands due to electron thermal pressure. As the plasma encounters stronger fields, expansion slows and the density distribution molds to the field. UCNP electrons are strongly magnetized over most of the plasma, while ion magnetization is only significant at the boundaries. Observations suggest that electrons and ions are predominantly trapped by magnetic mirroring and ambipolar electric fields, respectively. Confinement times approach 0.5 ms, while unmagnetized plasmas dissipate on a timescale of a few tens of microseconds.
我们展示了在双锥尖点或四极磁场的零点处产生的超冷中性等离子体（UCNP）的磁约束。最初，UCNP由于电子热压力而膨胀。当等离子体遇到更强的磁场时，膨胀减缓，密度分布适应磁场。UCNP电子在等离子体的大部分区域被强烈磁化，而离子磁化仅在边界处显著。观察结果表明，电子和离子分别主要被磁镜反射和双极电场捕获。约束时间接近0.5毫秒，而未磁化的等离子体在几十微秒的时间尺度上消散。
