The measurement of the axially lost electron energy distribution escaping from a minimum-B electron cyclotron resonance ion source in the range of 4–800 keV is reported. The experiments have revealed the existence of a hump at 150–300 keV energy, containing up to 15% of the lost electrons and carrying up to 30% of the measured energy losses. The mean energy of the hump is independent of the microwave power, frequency and neutral gas pressure but increases with the magnetic field strength, most importantly with the value of the minimum-B field. Experiments in pulsed operation mode have indicated the presence of the hump only when microwave power is applied, confirming that the origin of the hump is radio-frequency-induced momentum space diffusion. A possible mechanism of the hump formation is considered based on the quasi-linear model of plasma–wave interaction.

据报道，从最小B电子回旋共振离子源逃逸出的轴向损失电子能量分布在4–800 keV范围内。实验表明，在150–300 keV能量处存在一个驼峰，其中包含多达15％的失去的电子和高达30％的测量能量损失。驼峰的平均能量与微波功率，频率和中性气体压力无关，但随磁场强度而增加，最重要的是随最小值B的值增加场地。在脉冲操作模式下进行的实验表明，只有在施加微波功率时，才会出现驼峰，这证实了驼峰的起源是由射频引起的动量空间扩散。基于等离子体-波相互作用的准线性模型，考虑了驼峰形成的可能机理。