Modeling Nuclear Fusion with Strongly Magnetized Non-Neutral Plasmas

在高温等离子体中，聚变能量只有在原子核之间的近距离碰撞(即小碰撞参数、高能碰撞)时才释放出来。同样，在强磁化的纯电子或纯离子等离子体中，电荷的回旋能量被束缚在较小的高频回旋轨道上，只有在近距离碰撞的情况下才会释放。在初始回旋能量比平行于磁场的运动能量大得多的状态下，可以制备单物种等离子体，因此在近距离碰撞中释放的回旋能量会加热平行运动。因此，人们可以认为回旋加速器能类似于核能。研究人员将利用这个类比来开展与聚变物理相关的实验和理论研究。特别是，他们将首次测量强耦合等离子体中核反应速率的强烈增强。这种“屏蔽”增强是由Salpeter在1954年预测的，对于高密度的聚变尤其重要，例如在白矮星中。此外，研究人员还将利用强磁化等离子体研究“燃烧动力学”，并开展与这两个实验相关的理论。这些实验将在加州大学圣迭戈分校物理系非中性等离子体物理组的IV装置和位于科罗拉多州博尔德的NIST的Penning离子陷阱设施上进行。这项工作与等离子体物理、天体物理和核物理建立了强有力的跨学科联系。

In high temperature plasmas, fusion energy is released only as a result of close collisions between nuclei (i.e. small impact parameter, energetic collisions). Likewise, in strongly magnetized pure electron or pure ion plasmas, the cyclotron energy for a charge is bound up in small high frequency cyclotron orbits, and is released only as a result of close collisions. Single species plasmas can be prepared in a state where the initial cyclotron energy is much larger than the energy of motion parallel to the magnetic field, so the cyclotron energy that is released in close collisions heats the parallel motion. One may therefore think of cyclotron energy as being analogous to nuclear energy. The investigators will use this analogy to carry out experimental and theoretical investigations relevant to fusion physics. In particular, they will measure, for the first time, the strong enhancement of the nuclear reaction rate in strongly coupled plasmas. This "screening" enhancement was predicted by Salpeter in 1954, and is particularly important for fusion at high densities, such as in white dwarf stars. In addition the investigators will study "burn dynamics" using strongly magnetized plasmas, and carry out theory relevant for both experiments. The experiments will be conducted on the IV apparatus of the non-neutral plasma physics group in the Physics Department of UCSD, and on the Penning ion trap facility at NIST, Boulder, CO. The work makes strong interdisciplinary connections, with plasma physics, astrophysics, and nuclear physics.