Discharge circuits and loads Page: 23 of 62
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DISCHARGE CIRCUITS AND LOADS
than the theoretical formula predicts. For two or three times, they are an
economical way of stepping up voltages. All comments made for the same
transformer using ferrite cores to increase permeability also apply to
For overall pulser efficiencies, a rough number is about 60 to 80%,
which has not changed significantly since the 1940s. A repetition-rate
system, even at 1 to 2 kHZ has a given input power of about 70% of a given
aut power for the system.. This is due to heat lost in the diodes and
,ing unit, and switch losses. This applies to ignitrons, thyratrons,
scuun arc devices, and some thyristor (silicon-controlled rectifier)
modulators. Spark gaps in repetitive circuits can have quite large losses,
and overall system efficiencies can fall well below 60% at kilohertz repeti-
IV. SWITCH RECOVERY AND RESISTIVE EFFECTS
When a load turns off. the current decays towards zero. The reso-
nance effect in all the inductors with the stray capacitances and the
recharge circuit tries to put charge back on the PFN. The recovery time
for the switch device, whatever it is, is over the time so marked in Fig.
8. The area of the first negative pulse represents a positive ion energy
deposited inside the thyratron gas switch tube ("gAs cleanup"), which can,
in effect, increase the heat load on the tube and severely limit the life-
time.1 In large, high-repetition-rate systems, where the switch tube is
being pushed to the limit of its performance, an enormous amount of posi-
tive ion heating of the anode of the tube can occur, easily equaling the
anode heating of the tube during the switch turn-on time. A similar be-
havior can apply to spark gaps. Energy is deposited in several areas in-
side the gap until it fully recovers. Just how important that is depends
on the individual circuit.
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Sarjeant, W.J. Discharge circuits and loads, report, October 15, 1980; New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc1061299/m1/23/: accessed April 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.