标题： 热与电流淬火的对齐与高密度低原子序数注入 显示英文标题

标题： Aligning Thermal and Current Quenches with a High Density Low-Z Injection

摘要： 传统的方法是在托卡马克中断中通过高-Z杂质注入来缓解热淬灭，该方法在等离子体的热能到达壁面之前将其辐射掉。 缺点是由于辐射约束的低后热淬灭电子温度导致欧姆电流到奔溃电流的转换非常强烈。 另一种方法是部署低-Z（氘或氢）注入，旨在减缓热淬灭，并理想地使其与电流淬灭同步。 在此通过使用PIXIE3D代码的三维MHD模拟对此方法进行了研究。 通过增加氢气密度，在大约原始压力下对聚变级等离子体进行稀释冷却。 除了体状辐射损失外，能量损失到壁面由边界处的博姆流出条件控制，其中磁场在壁面处与薄等离子体鞘层相交。 MHD不稳定性照常发生，而等离子体的碰撞频率大大增加，平行输运现在处于布拉金斯基区域。 本研究的主要结论是，由于足够的低-Z注入导致沿开放场线的输运损失减少，使热淬灭速率减缓到约20毫秒，与15 MA ITER等离子体的电流淬灭时间尺度一致。 显示英文摘要

摘要： The conventional approach for thermal quench mitigation in a tokamak disruption is through a high-Z impurity injection that radiates away the plasma's thermal energy before it reaches the wall. The downside is a robust Ohmic-to-runaway current conversion due to the radiatively clamped low post-thermal-quench electron temperature. An alternative approach is to deploy a low-Z (either deuterium or hydrogen) injection that aims to slow down the thermal quench, and ideally aligns it with the current quench. This approach has been investigated here via 3D MHD simulations using the PIXIE3D code. By boosting the hydrogen density, a fusion-grade plasma is dilutionally cooled at approximately the original pressure. Energy loss to the wall is controlled by a Bohm outflow condition at the boundary where the magnetic field intercepts a thin plasma sheath at the wall, in addition to Bremsstrahlung bulk losses. Robust MHD instabilities proceed as usual, while the collisionality of the plasma has been greatly increased and parallel transport is now in the Braginskii regime. The main conclusion of this study is that the decreased transport loss along open field lines due to a sufficient low-Z injection slows down the thermal quench rate to the order of 20 ms, aligned with the current quench timescale for a 15 MA ITER plasma.