ELECTRONICALLY-CONTROLLED, CURRENT-INJECTION SPARK SOURCE FOR BASIC AND APPLIED EMISSION SPECTROMETRY

A spark source of high versatility is described. Using a crystal-controlled oscillator and frequency multiplying amplifiers to feed a 500-watt power tube, a 162-megahertz sine wave is delivered to a quarter-wave-resonant, rigid, coaxial line containing the spark gap as an integral termination. The rapid buildup of a standing wave of progressively increasing voltage on the open end of the line forms the spark with high temporal precision. A current injection point is located at the sending end of the quarter-wave line where a radio-frequency voltage node exists, allowing maximum flexibility in generating a current waveform to sustain the discharge. The source offers freedom from radio-frequency interference, low-power electronic control and continuously adjustable repetition rates up to three kilohertz. © 1969, American Chemical Society. All rights reserved.