Positron injection and trapping for positron-electron pair plasma creation

由电子和正电子组成的“对等离子体”是唯一对称的等离子体，其中带正负电荷的粒子具有相同的质量(与标准等离子体中电子和离子之间的巨大质量差形成对比)。在对它们的性质进行了40多年的理论和计算预测之后，我们终于能够在实验室中创造和研究磁约束对等离子体。预计这一结果将对我们理解基础等离子体物理做出重大贡献，并对不同领域产生影响，从聚变能量的磁约束到自然产生电子-正电子等离子体的天体物理系统。在我们实现目标的过程中有三个关键挑战：(I)在适当的参数下获得足够的正电子，使之处于等离子体(集体行为)状态，(Ii)发展对这些正电子和相同数量的电子具有足够长的限制时间的陷阱，以及(Iii)将带电粒子转移到陷阱中(对于正电子的情况，这必须是非常有效的)。DFG支持我们的建议--将正电子注入磁偶极场以研究电子-正电子等离子体，这使得在所有三个挑战方面都取得了实质性进展。亮点包括将低能正电子无损地注入偶极磁场，在该磁场中对正电子进行长时间限制(超过一秒)，将正电子注入先前存在的电子空间电荷，以及模仿过去实验并指导未来实验设计的复杂模拟。由于这些结果，下一代陷阱的开发工作得以推进(并行，由其他来源资助)，这些陷阱能够限制更多的正电子和电子。在我们目前的方案中，我们解释了我们希望如何将我们上一个方案的成功应用于这些新的陷阱，从而进一步发展这些方法，并使我们在未来几年内实现双等离子体的目标。

"Pair plasmas" consisting of electrons and positrons are uniquely symmetric plasmas in which the negatively and positively charged particles have identical mass (in contrast to the large mass difference between electrons and ions in standard plasmas). After more than four decades of theoretical and computational predictions about their properties, we are finally on the verge of being able to create and study magnetically confined pair plasmas in the laboratory. The results are expected to make significant contributions to our understanding of fundamental plasma physics, with implications for diverse areas, from magnetic confinement for fusion energy to astrophysical systems in which electron-positron plasmas occur naturally. Three key challenges en route to our goal are (i) getting enough positrons at suitable parameters as to be in the plasma (collective behavior) regime, (ii) development of traps with sufficiently long confinement times for those positrons and an equal number of electrons, and (iii) transfer of the charged particles into the traps (which in the case of positrons must be highly efficient).Support from the DFG of our proposal "Positron Injection into a Magnetic Dipole Field for the Study of an Electron-Positron Plasma" has enabled essential progress with respect to all three of those challenges. Highlights have included lossless injection of low-energy positrons into a dipole magnetic field, long confinement (in excess of a second) of positrons in that field, injection of positrons into a preexisting electron space charge, and sophisticated simulations that mimic past experiments and guide the design of future ones. Thanks to these results, work has been able to move forward on the development (in parallel, funded by other sources) of next-generation traps capable of confining larger numbers of positrons and electrons. In our current proposal, we explain how we would like to apply our successes from our last proposal to these new traps, thereby further developing these methods and bringing us to our goal of pair plasmas within the next few years.