Extensive analysis of disruptions in JET has helped advance the understanding of trends of disruption-generated runaway electrons. Tomographic reconstruction of the soft x-ray emission has made possible a detailed observation of the magnetic flux geometry evolution during disruptions. With the aid of soft and hard x-ray diagnostics runaway electrons have been detected at the very beginning of disruptions. A study of runaway electron parameters has shown that an approximate upper bound for the conversion efficiency of pre-disruptive plasma currents into runaways is about 60% over a wide range of plasma currents in JET. Runaway generation has been simulated with a test particle model in order to verify the results of experimental data analysis and to obtain the background for extrapolation of the existing results onto larger devices such as ITER. It was found that close agreement between the modelling results and experimental data could be achieved if in the calculations the post-disruption plasma electron temperature was assumed equal to 10 eV and if the plasma column geometry evolution is taken into account in calculations. The experimental trends and numerical simulations show that runaway electrons are a critical issue for ITER and, therefore, the development of mitigation methods, which suppress runaway generation, is an essential task.
JET中破裂的广泛分析有助于加深对破裂产生的逃逸电子趋势的理解。软X射线发射的层析重建使得在破裂期间能够详细观测磁通量几何结构的演化。借助软、硬X射线诊断，在破裂的最初阶段探测到了逃逸电子。对逃逸电子参数的研究表明，在JET中较宽的等离子体电流范围内，破裂前等离子体电流转化为逃逸电子的转换效率的上限约为60%。为了验证实验数据分析的结果，并为将现有结果外推到如ITER等更大装置提供背景依据，使用测试粒子模型对逃逸电子的产生进行了模拟。研究发现，如果在计算中假设破裂后的等离子体电子温度为10 eV，并考虑等离子体柱几何结构的演化，模拟结果与实验数据能够达到良好的一致性。实验趋势与数值模拟均表明，逃逸电子对ITER构成关键问题，因此，抑制逃逸电子产生的缓解方法是至关重要的任务。