Design of a 150 kV, 300 A, 100 Hz Blumilein coaxial pulser for long pulse operation

Summary form only given, as follows. Blumlein Pulsers can be used in many applications such as high power microwave generators and x-ray generation. The reason for this is that they are capable of generating high voltage pulses of several hundreds of kV in the range of ns. These devices consist of several stacked Blumlein lines charged in parallel and discharged synchronously in series into the load. Normally the commutation of Blumlein lines is made by using a single switch at the pulser input. Unfortunately, in this circuit configuration the pulser voltage gain efficiency is reduced by the presence of parasitic lines in the pulser structure which can never be fully eliminated. One way of improving the gain efficiency is to increase the parasitic line impedance Z/sub P/ by winding the pulser transmission lines. This makes coaxial cables more suitable than strip lines for this configuration. Moreover, for long pulse operation above 500 ns (required for plasma immersion ion implantation applications) coaxial cable windings are more compact than long straight strip lines. In this paper, we are proposing, for the first time, the construction of a coaxial Blumlein pulser with pulse duration of 1 /spl mu/s. Other pulser design characteristics are: output voltage and current of 150 kV/300 A at a repetition frequency of 100 Hz. The device will be built by stacking five Blumlein lines with long lengths (100 m each) of 50 /spl Omega/ coaxial lines wounded around polyethylene tubes. The pulser design has been assessed by a modified model used originally to predict voltage gain of similar TLT devices. This model gives the open voltage gain in function of the number n of stacked Blumlein lines, the Blumlein impedance Z/sub B/=2Z/sub 0/ (where Z/sub 0/ is the cable characteristic impedance) and the parasitic impedance Z/sub p/.