A Blumlein based on helical line storage elements was conceived and developed for generation of a rectangular pulse of 150 kV, 5 μs duration and which can drive a load of about 1 kΩ impedance. The helical line consisting of an aluminum tube of 750 mm length and 100 mm diam, wound with mylar film insulation to withstand 200 kV and then wound with copper wire was built and tested in our laboratory. It has a capacitance of 1.2 nF and has a characteristic impedance of 2 kΩ. The pulse generator built here, uses ten such coils in Blumlein configuration with five elements in parallel in each section giving total capacitance of about 10 nF. It has the advantages of compactness, simplicity, low cost, reliability, and high performance towards good flat top, low rise time, and small jitter. It can be designed to match load impedances in the range of a few ohms to several kilo ohms. This pulse power system was built and successfully tested for accelerating electrons in the gun chamber of an electron beam controlled CO2 laser operating in the single shot mode. This article describes the design, fabrication, and performance of the pulse power system.

In the past, it has been presumed that the main-gap breakdown in a trigatron is caused by a precursor spark channel occurring either at the trigger gap or between a trigger electrode and oppositely located main electrode. Based on the detailed analysis of voltage and current waveforms at the trigger gaps of single- and double-mode gas trigatrons, the authors have proposed an interaction between the main gap and the trigger gap under favourable conditions. This interaction gives rise to two or more auxiliary spark channels which develop between different over-volted electrode pairs in a predictable manner. The enhanced UV illumination and electric field distortion as a result of these multiple auxiliary arcs lead to the development of a streamer breakdown between the main electrodes.

The present article describes the constructional aspects of an 85-kJ capacitor bank at 20 kV for the production of pulsed high magnetic fields. The discharge current magnitude is 56 kA at a ringing frequency of 1.1 kHz. The bank employs 8 double-mode trigatrons in parallel which are triggered into conduction by the application of 16 simultaneous low jitter high voltage pulses generated by a multiple trigger pulse generator. The performance of the bank with double-mode trigatrons is compared with that obtained by conventional single-mode trigatrons. The waveforms of discharge current in time domain and fast fourier frequency spectrum for single- and double-mode trigatrons are presented and analyzed for performance evaluation. The performance with double-mode trigatrons is characterized by distinctly superior synchronization in the closing of trigatron switches over a wide range of operating voltage resulting in high peak discharge current and low waveform distortion.

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