Pulsed Power Group Research Articles

A 10 GW Tesla-Driven Blumlein Pulsed Power Generator

A repetitive 0.6 MV, 10 GW Tesla-driven Blumlein pulsed power generator, with an overall energy efficiency in excess of 90%, has been designed, manufactured and demonstrated by the Pulsed Power Group at Loughborough University. This paper describes the application of various numerical techniques used to design a successful generator, such as filamentary modeling and electrostatic and transient circuit analysis. All the major parameters of both the Tesla transformer and the Blumlein pulse-forming line were determined, enabling accurate modeling of the overall unit to be performed. The wide-bandwidth embedded sensors used to monitor the dynamic characteristics of the overall system are also presented. Experimental results obtained during this major experimental program are compared with theoretical predictions and the way ahead toward generating faster output voltage impulses is considered.

A Compact Battery-Powered Half-Megavolt Transformer System for EMP Generation

High-power electromagnetic pulses are of importance in a variety of applications such as transient radar and particle accelerators and when investigating the effect of strong radio-frequency impulses on electronic systems. With all these possibilities in mind, a compact and portable source has been developed by the Plasma and Pulsed Power Group, Loughborough University, U.K., in collaboration with the Defense Science and Technology Laboratory, U.K. The source is based on a pulsed resonant Tesla transformer that produces nanosecond rise-time pulses at voltages exceeding 0.5 MV. In addition to the Tesla transformer, the other major components include a pulse forming line, a high-voltage fast spark gap switch, and a half-wavelength dipole antenna. The pulsed radiated electric field measured at 10 m from the source has a peak amplitude of 12.4 kV/m

Loughborough 2-D simulation of MURI flux-compression generators

A number of single-pitch minihelical flux-compression generators have been designed, manufactured and tested by Texas Tech University and the University of Missouri-Rolla, as part of a Multidisciplinary University Research Initiative (MURI). Several other Institutions have collaborated in the program, by providing theoretical predictions of the output performance of a generator without having access to the experimental data or making any consequent parameter changes in their numerical codes. As part of this activity, the Plasma and Pulsed Power Group at Loughborough University, Leicestershire, UK., has used its extensively documented and well-proven two-dimensional (2-D) filamentary modeling approach in conducting detailed theoretical considerations of the behavior of one of the generators. A number of fundamental features of the simulation are described in the paper, such as the inclusion of phase transition in the conductors and the effect of the very high electric field intensity in the contact point region. The ability of the code to provide accurate predictions of the actual generator performance for very-high-input currents is provided by the good agreement achieved with experimental results presented by TTU.

New developments in paraxial radiographic diode technology for focusing intense relativistic electron beams

The Pulsed Power Group at the Atomic Weapons Establishment (AWE) is interested in the generation of small, intense, multimegavolt X-ray sources for radiographic applications. For this paper, research has been carried out into electron beam transport and focusing studies on one of our single pulse forming line flash X-ray machines. Experiments were undertaken on E Minor to improve the radiographic spot size generated by our "paraxial diode". This is a novel anode/cathode assembly designed to produce a small-diameter electron beam focused onto a high-Z target. Electrons are propagated through a gas-filled cone such that their electrostatic repulsive and magnetic attractive forces are almost cancelled. The cone's length and gas pressure were initially optimized and then specific gas species applied to the drift cone. Helium gas improved spot size reproducibility with respect to variations in drift gas pressure when compared with dry air. The addition of a "secondary cell" to increase the neutralization of the electron beam's self-electric forces yielded a 30% improvement in measured radiographic spot size.

Nanosecond pulse techniques

This note was designed as an overview to help general workers build small to medium-sized pulse power machines. The note covers in broad outline the approaches available and provides formulae and breakdown data of an adequate nature to do this. The author reviews pulsed high-voltage techniques and reports on work by the pulsed power group at Atomic Weapons Research Establishment (AWRE), Aldermaston, UK, which has elucidated some of the design features of high-voltage pulsed systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>