Toshimitsu Murasaki

A New Method for Current ``Crowbar,'' Utilizing Reflected Shock Waves

A new method is proposed for crowbar techniques utilizing the ionization behind reflected shock waves in air. We can easily crowbar discharge currents when we make the time of the current peak coincide with the arrival of the shock wave at the crowbar gap.

Gas conditions after the passage of reflected shock waves and their application to torus‐like experiments

In this article we describe briefly recent results on basic processes concerning a crowbar method utilizing reflected shock waves by a pressure‐driven shock tube. After that, we propose an apparatus which is an application of this crowbar technique to a new method for producing plasmas.

Crowbar Experiments by Ionizing Shock Waves and New Methods to Produce Torus Like Plasmas

Various data on basic processes concerning crowbar methods by ionizing shock waves were gathered to apply this technique to the real and larger machines. A pair of crowbar electrodes were flush mounted at the end of a pressure driven shock tube which was terminated with a dielectric plate for shock reflection. Rather restricted shape of crowbar electrodes and use of ambient air in laboratory as a test gas did not decrease so much the insulating voltage of the crowbar gaps. To breakdown the crowbar gaps by reflected shock waves with the incident mach number of 7 ~ 16 in air at the initial pressure of 5 ~ 250 μHg, electrodes voltage must be applied by 700 ~ 400 V and the deduced conductivity of shocked plasmas was 10−11 ~ 10−9 Ω/cm. Two kinds of test circuits were tried to be crowbared. CRT traces of the discharge current with the crowbar gap closed by reflected shock waves showed successful and monotonous envelopes of the oscillating ones without the crowbarring. Various important improvements and another application of this type of experiments are proposed and shown briefly. Among them is a new method to produce torus-like plasmas, which is a different type of application of this crowbarring-idea, itself.