Spectroscopic method to measure the residual deuterium pressure during vacuum arc discharge with deuterated cathode

Abstract The pressure beyond the cathode surface is an important parameter in vacuum arc discharge. However, it is difficult to be measured because of its cramped space. A spectroscopic method using hydrogen gas as a tracer is proposed to measure the temporal residual deuterium pressure in a vacuum arc discharge with deuterated cathode. The principle of this method is that the spectral and chemical characteristics are almost the same for isotopes and atom spectrum intensity is proportional to its pressure. The method is in-situ and does not disturb the discharge. Besides the method could avoid the effect of cathode spot's random jumping. In order to verify the method, an integrated experiment is carried out. Different hydrogen gas flows are used in the experiment. The residual deuterium pressures are almost the same at different hydrogen gas flows, which is about 0.01 Pa when the discharge arc current is 90 A and pulse duration is 5 μs The low pressure may be caused by the large measurement space beyond cathode spots. The method could be used to measure temporal pressure in cramped space.