David J Coleman

US Patent:

40557839, Oct 25, 1977

Filed:

Mar 1, 1976

Appl. No.:

5/662891

Inventors:

John P. Walters - Madison WI
David M. Coleman - Madison WI

Assignee:

Wisconsin Alumni Research Foundation - Madison WI

International Classification:

G01J 330
H05B 720

US Classification:

315241R

Abstract:

The disclosed spark source is adapted to generate electrical sparks to produce light for spectroscopic analysis of materials placed on the spark gap electrodes or introduced into the sparks. The disclosed spark source comprises a high voltage transformer having a secondary winding for supplying alternating current at a high voltage, a storage capacitor, a charging circuit including a rectifier connected between the secondary winding and the capacitor for charging the capacitor, spark gap electrodes having a spark gap therebetween, a discharge circuit including an electronic switching device connected between the capacitor and the spark gap electrodes for discharging the capacitor across the spark gap and control means for supplying a sequence of variably spaced triggering pulses to the input means of the electronic switching device for producing a sequence of spark cycles in which the capacitor is charged to substantially the same voltage for all of the spark cycles. During the intervals between sparks, the capacitor is recharged by the transformer and the rectifier. The timing of the sparks is varied, with reference to the phase angle of the alternating current, so that the capacitor is charged to the same voltage during each of the intervals between sparks.