电流驱动与Alpha通道化介导的旋转驱动中的动量守恒
Momentum Conservation in Current Drive and Alpha-Channeling-Mediated Rotation Drive
AI总结：
本文针对alpha channeling旋转驱动中的动量守恒问题，构建了自洽的准线性理论，揭示了非共振粒子对随时间增长的平面波与具有非均匀空间结构的稳态波反应的根本差异，从而解释了稳态波如何驱动旋转。
摘要：
Alpha channeling利用波从聚变等离子体中提取热灰，同时将能量从灰转移到波上。引人注目的是，已有研究提出，提取这种带电灰可以产生径向电场，从而有效地驱动ExB旋转。然而，现有理论忽略了非共振粒子的响应，而这些粒子在准线性理论中执行动量守恒方面起着关键作用。由于跨场电荷输运与动量守恒在根本上是相互关联的，这种非一致性使得整个效应受到质疑。在此，我们回顾了近期在解决由alpha channeling引起的旋转驱动问题上取得的重要进展。我们为静电波构建了一个简单、通用且自洽的准线性理论，适用于bump-on-tail不稳定性等经典示例。作为直接推论，我们展示了在无碰撞等离子体中，即使没有动量注入，波如何也能驱动电流。为了将该理论应用于灰提取和旋转驱动问题，我们开发了首个能够捕捉alpha channeling过程的线性理论。由此产生的动量守恒线性-准线性理论揭示了非共振粒子对随时间增长的平面波与具有非均匀空间结构的稳态波的反应之间的根本差异，这使得后者能够驱动旋转，而前者则不能。这种差异可以通过两个守恒定律来理解，它们证明了该理论的局部和全局动量守恒。最后，我们展示了振荡中心理论通常如何掩盖随时间变化的非共振反冲，但最终会得出相似的结果。
英文摘要：
Alpha channeling uses waves to extract hot ash from a fusion plasma, while transferring energy from the ash to the wave. Intriguingly, it has been proposed that the extraction of this charged ash could create a radial electric field, efficiently driving ExB rotation. However, existing theories ignore the response of the nonresonant particles, which play a critical role in enforcing momentum conservation in quasilinear theory. Because cross-field charge transport and momentum conservation are fundamentally linked, this non-consistency throws the whole effect into question. Here, we review recent developments that have largely resolved this question of rotation drive by alpha channeling. We build a simple, general, self-consistent quasilinear theory for electrostatic waves, applicable to classic examples such as the bump-on-tail instability. As an immediate consequence, we show how waves can drive currents in the absence of momentum injection even in a collisionless plasma. To apply this theory to the problem of ash extraction and rotation drive, we develop the first linear theory able to capture the alpha channeling process. The resulting momentum-conserving linear-quasilinear theory reveals a fundamental difference between the reaction of nonresonant particles to plane waves that grow in time, versus steady-state waves that have nonuniform spatial structure, allowing rotation drive in the latter case while precluding it in the former. This difference can be understood through two conservation laws, which demonstrate the local and global momentum conservation of the theory. Finally, we show how the oscillation-center theories often obscure the time-dependent nonresonant recoil, but ultimately lead to similar results.
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