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.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.