Comparison of Measurement Reliability of Nanosecond Rectangular Voltage Pulses by Kerr Effect and by High-Speed Voltage Probe

Abstract

Recently, the idea of injecting energy with electromagnetic radiation in order to heat the plasma to achieve controlled fusion has been abandoned. This initially favored mechanism was rejected because it has been shown that after a certain temperature the plasma glows and acts as a mirror that reflects electromagnetic radiation. For that reason, today the energy is injected into the plasma by electrons. For this purpose, pulses from several electron beam generators, based on a Marx generator, are synchronously fired into the plasma. In addition to economic problems, the biggest problem of this method is the appearance of jitter, i.e., pulses with a width of about 5 ns are not simply added up but propagated in time due to the impossibility of synchronizing simultaneous triggering of the multiple electronic generators. In order to avoid this, the possibility of monitoring the pulses from an individual electron beam generator for the purpose of online synchronization is investigated in this paper. The voltage pulse monitoring of the electron beam generator was measured by instruments with the fastest response—the electro-optical Kerr effect and a fast capacitive probe. The obtained results showed that the electro-optical Kerr response is somewhat faster but much more complicated, so the use of fast capacitive probes is recommended for practice.