A Tesla-pulse forming line-plasma opening switch pulsed power generator

A pulsed power generator based on a high-voltage Tesla transformer which charges a 3.85 /55 ns water-filled pulse forming line to 300 kV has been developed at Loughborough University as a training tool for pulsed power students. The generator uses all forms of insulation specific to pulsed power technology, liquid oil and water , gas SF6 , and magnetic insulation in vacuum, and a number of fast voltage and current sensors are implemented for diagnostic purposes. A miniature centimeter-size plasma opening switch has recently been coupled to the output of the pulse forming line, with the overall system comprising the first phase of a program aimed at the development of a novel repetitive, table-top generator capable of producing 15 GW pulses for high power microwave loads. Technical details of all the generator components and the main experimental results obtained during the program and demonstrations of their performance are presented in the paper, together with a description of the various diagnostic tools involved. In particular, it is shown that the miniature plasma opening switch is capable of reducing the rise time of the input current while significantly increasing the load power. Future plans are outlined in the conclusions

Quality factor measurements of air-cored solenoids at overtone frequencies

Although Tesla transformers and helical cavity filters are employed in quite different technical areas, a previous contribution demonstrated that applying the techniques used in designing these filters to the secondary winding configurations of a Tesla transformer improved the spectral purity of the output. In the present reported work, measurements of the quality factors of the original and a number of modified secondary windings are shown to provide results at the fundamental and overtone frequencies, thereby illustrating the scale of the possible benefits that can be achieved

Significant practical features of Tesla transformers

Although a large number of publications dealing with Tesla transformers have appeared, many of these are confined to providing an analysis of the transformer performance based on a lumped equivalent circuit model. The present paper is concerned with more practical issues and begins by considering the often overlooked significance of the magnetic coupling between the primary and secondary windings for the range of potential applications of these transformers. It continues by discussing the benefits of using a solid-state primary switch and providing an insight into various other additions that may be made to the basic circuit

Optimizing the secondary coil of a tesla transformer to improve spectral purity

This paper provides an overview of the response of the tuned secondary circuit of a Tesla transformer, following impulse excitation from the tuned primary circuit. Multiorder oscillatory voltages and currents are energized in the secondary circuit, and research is ongoing to determine the fundamental and higher order modes for various secondary winding configurations, with the aim of developing design techniques that can be used to suppress the generation of the higher order modes. It is anticipated that this will lead to generators which exhibit enhanced spectral purity and which will be better suited to use in electronic warfare applications than conventionally wound Tesla transformers. © 2013 IEEE

High power RF capabilities at Loughborough University

Members of the plasma and pulsed power group at Loughborough University are engaged in several experimental activities related to the generation of high power radio frequency radiation. The paper reviews some of the more important projects that have recently been successfully completed

Bipolar modulation of the output of a 10-GW pulsed power generator

A bipolar Blumlein former has been designed and successfully implemented as an extension to an existing 10-GW-Tesla-driven Blumlein pulsed power generator. The new system is capable of generating a voltage impulse with a peak-to-peak value reaching 650 kV and having a high-frequency limit of the bandwidth well in excess of 1 GHz. Constructional details are provided, together with experimental results and analysis using the 3-D software modeling of the bipolar former that provides the results in good agreement with experimental data

A miniature high-power pos driven by a 300 kV Tesla-charged PFL generator

A pulsed power generator based on a high-voltage Tesla transformer charging a 3.8 ¿/53 ns water-filled pulse forming line (PFL) to 300 kV has been developed at Loughborough University as a training tool for pulsed-power students. The generator uses all forms of insulation specific to pulsed power technology - liquid (oil and water), gas (SF6) and vacuum, a series of fast voltage and current sensors, and is able to produce multi-GW pulses on a simple x-ray diode load. Recently, a miniature (cm-size) plasma opening switch (POS) using protons (H+ ions) has been coupled to the output of the Tesla-charged PFL generator, with the overall system constituting the first phase of a programme aimed at the development of a novel repetitive, table-top generator capable of producing 15 GW pulses for high power microwave loads. Experimental results demonstrating the performance of the POS in reducing the rise time of the input current while increasing the load power are presented, together with constructional details and diagnostic techniques. Future plans are outlined

A 10 GW Tesla-driven Blumlei 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. The paper describes the application of various numerical techniques used to design a successful generator, such as filamentary modelling 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 modelling 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 predict ions and the way ahead towards generating faster output voltage impulses is considered

An innovative and non-invasive technology for PEF food processing

The use of pulsed electric fields (PEFs) is a mature technology used in the industrial processing of food, for example, fruit juice. It is however restricted to liquid (pumpable) food and involves metal electrodes in direct contact with the foodstuff – i.e. it is at present an inherently ‘invasive’ technology. Recently, Loughborough University has undertaken an experimental programme aimed at demonstrating a new and ‘non-invasive’ technology that uses an antenna coupled to a fast high-voltage pulse generator to produce an intense pulsed electric field. The machine that has been built and undergone preliminary testing uses a Teslatransformer- based pulse forming line generator coupled to a Valentine antenna to produce very intense electric fields in water. The technology developed offers considerable scope for use with any type of food, including solid foods such as meat. Apart from the much greater volume available for processing, and other more or less obvious advantages, the new technique is also highly energy efficient as, unlike the existing invasive approach, it does not drive a current through the food being processed. The paper presents the experimental equipment and explains the type of sensors that need to be developed for measurement of the electric field produced. Some of the major implications the technique may offer for the future of PEF food processing are introduced

MIDOT: A novel probe for monitoring high-current flat transmission lines

A novel inductive probe, termed MIDOT, was developed for monitoring high-current flat transmission lines. While being inexpensive the probe does not require calibration, is resistant to both shock waves and temperature variations, and it is easy to manufacture and mount. It generates strong output signals that are relatively easy to interpret and has a detection region limited to a pre-defined part of the transmission line. The theoretical background related to the MIDOT probes, together with their practical implementation in both preliminary experimentation and high-current tests, is also presented in the paper. The novel probe can be used to benchmark existing 2D numerical codes used in calculating the current distribution inside the conductors of a transmission line but can easily detect an early movement of a transmission line component. The probe can also find other applications, such as locating the position of a pulsed current flowing through a thin wire