Importance

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Abstract

A high pulse repetition frequency (PRF) plasma gun is provided, which gun inlets a selected propellant gas into a column formed between a center electrode and a coaxial outer electrode, utilizes a solid state high repetition rate pulse driver to provide a voltage across the electrodes and provides a plasma initiator at the base of the column, which is normally operative when the driver is fully charged. For preferred embodiments, the initiator includes RF driven electrodes. The plasma expands from the base end of the column and off the exit end thereof. When used as a thruster, for example in space applications, the driver voltage and electrode lengths are selected such that the plasma for each pulse exits the column at approximately the same time the voltage across the electrodes reaches zero, thereby maximizing the thrust. When used as a radiation source, the voltage and electrode length are selected such that the plasma exits the column when the current is maximum. The plasma is magnetically pinched as it exits the column, thereby raising the plasma temperature, energizing an element in gas state applied to the pinch, for example through the center electrode to provide radiation at a desired wavelength. The plasm gun parameters can be selected to achieve a desired wavelength, which may for example be within the EUV band. In particular, the pinch temperature is preferable high enough to ionize a significant portion of the gas applied to the pinch to its single election state, thereby producing radiation at the wavelength having maximum intensity If a longer, lower-intensity wavelength is desired, filtering of at least higher intensity, shorter wavelengths concurrently generated is desirable. Temperature at the pinch can also be selected to control the type of emission to minimize output angle of the radiation. The plasma gun of this invention, which is capable of operating at PRFs in the range of approximately 100 Hz to in excess of 5,000 Hz, may also be used in other applications.

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First Claim