Kafi M, Salar Elahi A, Ghoranneviss M, Ghanbari M R, Salem M K
Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.
J Synchrotron Radiat. 2016 Sep 1;23(Pt 5):1227-31. doi: 10.1107/S1600577516010262. Epub 2016 Aug 4.
In a tokamak with a toroidal electric field, electrons that exceed the critical velocity are freely accelerated and can reach very high energies. These so-called `runaway electrons' can cause severe damage to the vacuum vessel and are a dangerous source of hard X-rays. Here the effect of toroidal electric and magnetic field changes on the characteristics of runaway electrons is reported. A possible technique for runaways diagnosis is the detection of hard X-ray radiation; for this purpose, a scintillator (NaI) was used. Because of the high loop voltage at the beginning of a plasma, this investigation was carried out on toroidal electric field changes in the first 5 ms interval from the beginning of the plasma. In addition, the toroidal magnetic field was monitored for the whole discharge time. The results indicate that with increasing toroidal electric field the mean energy of runaway electrons rises, and also an increase in the toroidal magnetic field can result in a decrease in intensity of magnetohydrodynamic oscillations which means that for both conditions more of these high-energy electrons will be generated.
在具有环形电场的托卡马克装置中，超过临界速度的电子会自由加速并能达到非常高的能量。这些所谓的“逃逸电子”会对真空容器造成严重损坏，并且是硬X射线的危险来源。本文报道了环形电场和磁场变化对逃逸电子特性的影响。一种可能的逃逸电子诊断技术是检测硬X射线辐射；为此，使用了闪烁体（碘化钠）。由于等离子体开始时的回路电压较高，该研究是在等离子体开始后的前5毫秒内对环形电场变化进行的。此外，在整个放电时间内监测环形磁场。结果表明，随着环形电场增加，逃逸电子的平均能量升高，并且环形磁场的增加也会导致磁流体动力学振荡强度降低，这意味着在这两种情况下都会产生更多这些高能电子。
