Experimental Study on the Current Transmission Efficiency for the Transition Structure of Vacuum Transmission Line MITL on Flash-II Accelerator

Abstract

An experimental platform based on a coaxial cylinder magnetically insulated transmission line (MITL) was established on the basis of Flash-II accelerator. An experimental study was conducted on the current loss characteristics of the transition region between the vacuum transmission line and the MITL under different impedance match conditions by adjusting the loading gap of an e-beam diode. The results showed that under shorted load, the whole vacuum transmission region suffers no current loss. Furthermore, the voltage waveform continuously decreases when approaching the load region. When the load impedance is smaller than the working impedance of the transmission line, the MITL becomes undermatched, and the current transmission efficiency of the transition region reaches 98% without the evident current loss. When the load impedance increases to make MITL overmatched, an MITL operates under a self-limited flow accompanied with huge current loss in the transition region. The current transmission efficiency decreases to 87%, and the current loss process significantly affects the working process of the probe on an anodic differential coil. On the basis of the working mechanism of an MITL and the wave reflection process, a qualitative analysis was conducted, and the experimental results were explained.