A study of secondary winding designs for the two-coil Tesla transformer

The multi-order response of the tuned secondary circuit of a Tesla transformer, following impulse excitation from its tuned primary circuit, is presented and analysed at the fundamental resonant frequency and at higher-order mode frequencies. A novel way of modifying the frequency response of the secondary coil is then investigated by utilising a technique normally applied to the design of a certain type of filter known as a helical filter. In general, these are used in radio and microwave frequency circuits in order to pass certain frequencies with little attenuation whilst significantly attenuating other frequencies. Design techniques, developed over several decades, modify and optimise the performance of such filters. The frequency response of the helical filter is modified by altering the geometry of the helical resonator component therein, which is typically in the form of an air-cored single-layer solenoid. A Tesla transformer whose secondary is constructed to be some form of single-layer solenoidal winding resonates at its designed frequency - its fundamental mode - but also at non-integer harmonics (higher-order anharmonic frequencies, also known as overtones). Those multi-order oscillatory voltages and currents energised in the secondary circuit have been identified and measured and research has determined the fundamental and higher-order mode frequencies and amplitudes for various experimental secondary winding configurations derived from helical filter design techniques. Applied to the Tesla transformer secondary winding, such techniques lead to a new design with a performance that is improved by the suppression of higher- order anharmonic frequencies whilst imparting little change to the fundamental response. It is anticipated that this feature will lead to Tesla transformers which exhibit enhanced spectral purity and which will be better suited to use in certain pulsed power applications than conventionally wound designs

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

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

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

Improvements to secondary windings of Tesla transformers

Impulse excitation of the tuned primary circuit of a Tesla transformer generates a voltage and current response in the similarly tuned secondary circuit that contains both a fundamental component and a series of multiple higher-order modes. This paper investigates the most significant of these modes, in order to demonstrate a design approach that, when applied to the secondary winding, can bring about a reduction in the higher-order modes without significantly affecting the fundamental term. The resulting process leads to an improved spectral purity of the transformer output, making it better suited than existing conventional designs for application in electronic warfare and other high-power systems

Magnetic coupling in Tesla transformers

Although many publications dealing with Tesla transformers have appeared, most are confined to detailed investigations of the transformer performance based on a lumped equivalent circuit. The present paper differs widely from these in being concerned with the very practical and important issue of the degree of magnetic coupling between the two transformer windings and considers in detail the importance of the coupling factor for a range of applications of these transformers. The constructional features that may be adopted in various practical implementations are explained

Electromagnetic radiation from a Tesla transformer

In addition to the resistive and dielectric losses that inevitably occur near the secondary winding of a Tesla transformer, electromagnetic radiation into the far field also contributes to the overall power losses and thereby reduces both the effective quality factor (Q) and the power transfer efficiency of this winding. A short study of these effects for a laboratory scale transformer has shown that, in addition to its Q-factor being considerably reduced, the secondary winding is an extremely inefficient radiator of electromagnetic energy