Magnetically Delayed Pseudospark Switch

We have investigated the properties of a magnetically delayed pseudospark switch (PSS). One of the challenges of all low pressure gas discharge switches is the reduction of the lifetime due to commutation losses resulting in anode heating. This effect can be minimized by carefully dimensioning the saturating inductors. For many decades, this method has been successfully used for thyratrons. In principle, a saturating inductor prevents current flow until the end of the commutation phase. In contrast to thyratrons a PSS is based on a cold cathode electrode. To reach the low-resistive phase in a PSS, a significant current flow is necessary to allow self-heating of the cathode. A useful compromise has to be found to fulfill these opposing needs. The test setup is shown in Figure 1. Different saturating inductors are connected in series with the PSS, on the anode side. Three different designs of the FINEMET (FT3H) pulsed power core types were used. These cores use a thin ceramic insulation to provide a high break down voltage. The properties of the tested saturating inductors are summarized below.