Marx Circuit Research Articles

Simple, multiple arc, dielectric switch applied to a theta pinch

The construction and the operating details of a simple, field distortion, dielectric switch first used by Martin at A.W.R.E. and later extensively investigated by Dokopoulos at Jülich are presented. The switch, triggered by a small, fast Marx circuit, holds off approximately 110 kV and switches 70 kV at 500 kA with an inductance of 12 nH. The switch produces multiple arcs through the switch package without meticulous switch package preparation, with pitted and scarred switch electrodes, and with a relatively slow trigger system. The dielectric switch is used in a fast theta pinch system and is designed to facilitate ease of operation, switch package preparation, and repeatable performance.

The Generation of Lightning and Switching Impulse Voltages in the UHV Region with an Improved Marx Circuit

This paper concerns the trigger performance of Marx circuits and shows the essential features of an improved circuit. It is studied how the introduction of parallel spark gaps PF and firing capacitors CZ in a multi-stage impulse generator can improve the trigger performance. Other advantages of the new circuit will also be discussed.

1268. Electrical conductivity and thermal emf of thin mercury sulphide films of cubic modification: D M Freik et al, Izv VUZ Fiz, 11 (4), 1968, 143–115 ( in Russian)

A small low-inductance spark chamber pulser of simple construction is described. It has a capacity of 16000 pF, a series inductance of 8 nH exclusive of the spark inductance and will drive a 5500-pF load with a rise time of 14 nsec. The complete pulser measures 1.8 × 6 × 18 cm. An avalanche transistor Marx circuit that can be used to drive the pulser is also described. It triggers on 2-V pulses and drives the spark gap trigger electrode with a 1.2-kV pulse having a delay time of 4 nsec and a rise time of 2 nsec.

1269. New method of obtaining Schottky barriers with semi-transparent metal films: Z Majewski and G Kazon, Bull Acad Polon Sci Ser Sci Tech, 16 (3), 1968, 271–275 ( in English)

A small low-inductance spark chamber pulser of simple construction is described. It has a capacity of 16000 pF, a series inductance of 8 nH exclusive of the spark inductance and will drive a 5500-pF load with a rise time of 14 nsec. The complete pulser measures 1.8 × 6 × 18 cm. An avalanche transistor Marx circuit that can be used to drive the pulser is also described. It triggers on 2-V pulses and drives the spark gap trigger electrode with a 1.2-kV pulse having a delay time of 4 nsec and a rise time of 2 nsec.

A compact low-inductance spark chamber pulser

A small low-inductance spark chamber pulser of simple construction is described. It has a capacity of 16 000 pF, a series inductance of 8 nH exclusive of the spark inductance and will drive a 5500-pF load with a rise time of 14 nsec. The complete pulser measures 1.8 × 6 × 18 cm. An avalanche transistor Marx circuit that can be used to drive the pulser is also described. It triggers on 2-V pulses and drives the spark gap trigger electrode with a 1.2-kV pulse having a delay time of 4 nsec and a rise time of 2 nsec.

A compact low-inductance spark chamber pulser

A small low-inductance spark chamber pulser of simple construction is described. It has a capacity of 16000 pF, a series inductance of 8 nH exclusive of the spark inductance and will drive a 5500-pF load with a rise time of 14 nsec. The complete pulser measures 1.8 × 6 × 18 cm. An avalanche transistor Marx circuit that can be used to drive the pulser is also described. It triggers on 2-V pulses and drives the spark gap trigger electrode with a 1.2-kV pulse having a delay time of 4 nsec and a rise time of 2 nsec.

High Voltage Impulse System

An alternative to the Marx circuit for the production of high voltage, high current pulses is developed. It employs a water-immersed spiral-wound stepup transformer to go from a capacitor bank charged to 100 kV to an output of 1 MV. A method for using such a transformer to pulse charge a second capacitor bank efficiently without very tight coupling is derived. It is shown that for total transfer of energy (except for dissipation) the two resonant frequencies of the primary and secondary LC circuits (each measured with the other circuit open) should be equal, while the two normal mode frequencies of the coupled circuit should be in the ratio of 2:1, implying a coupling coefficient of 3/5. The design and operation of such a system is described.

The generation of recurring high-voltage X-ray impulses

Voltage-multiplication devices, such as the Marx and similar inductance circuits, have been operated at high recurrence frequencies and used as voltage sources for X-ray generation. The merits of this arrangement and the problem of obtaining optimum X-ray efficiency are discussed in relation to the design of voltage network and X-ray tube.The operation of the generator depends upon the production of short rectangular pulses, and this has been achieved by incorporating delay lines in each stage of the generator. In consequence, the generator has a characteristic impedance which, for optimum efficiency, must equal the X-ray tube impedance. The latter is non-linear, but it is shown that this is an advantage rather than a disadvantage because it suppresses multiple reflections.The X-ray-tube problem differs from that of the ordinary constant-voltage tube in that a higher peak emission is required. The possibilities of using thermionic, field-emission or low-pressure gas-filled tubes are discussed.