This more of a rant than anything else.
I'm working on a problem with a circuit that drives a indirectly heated cathode in a ion source. The problem is the switching bias supply (600v 2.6a in current control mode) keeps exploding the output filter caps when the source is unstable when ionizing some gases. The data seems to indicate we are getting arcing (instead of a normal plasma discharge) from the heater plate 20 to 10 that's connected to the arc supply (60v 10a) as the source ages. This condition (while maintaining current control) is feeding back to the supply causing oscillation issues leading to a 'magic smoke' failure that I think is caused by NIR in the power supply.
http://www.powerguru.org/negative-input-resistance-and-rms-input-currents/
EDIT: add new link for above: http://members.aon.at/aseibt/publications/Neg. Input Resistance.pdf
Typical IHC Ion Source diagram
Does anyone have experience in solving this sort of problem with external output filters. I'm trying a few configurations of common-mode chokes and DC line capacitors before the choke to damp the load variations at the terminal of the bias supply. The vendor (not the supply OEM) has replaced the original internal aluminum electrolytics with low ESR types that I think are only making the problem worse.
Figure 8:
http://www.interpoint.com/product_documents/DC_DC_Converters_Output_Noise.pdf
GEN600-2.6 isolated analog programming
http://www.mouser.com/ds/2/475/93507100-253078.pdf
I'm working on a problem with a circuit that drives a indirectly heated cathode in a ion source. The problem is the switching bias supply (600v 2.6a in current control mode) keeps exploding the output filter caps when the source is unstable when ionizing some gases. The data seems to indicate we are getting arcing (instead of a normal plasma discharge) from the heater plate 20 to 10 that's connected to the arc supply (60v 10a) as the source ages. This condition (while maintaining current control) is feeding back to the supply causing oscillation issues leading to a 'magic smoke' failure that I think is caused by NIR in the power supply.
http://www.powerguru.org/negative-input-resistance-and-rms-input-currents/
EDIT: add new link for above: http://members.aon.at/aseibt/publications/Neg. Input Resistance.pdf
Typical IHC Ion Source diagram
Does anyone have experience in solving this sort of problem with external output filters. I'm trying a few configurations of common-mode chokes and DC line capacitors before the choke to damp the load variations at the terminal of the bias supply. The vendor (not the supply OEM) has replaced the original internal aluminum electrolytics with low ESR types that I think are only making the problem worse.
Figure 8:
http://www.interpoint.com/product_documents/DC_DC_Converters_Output_Noise.pdf
GEN600-2.6 isolated analog programming
http://www.mouser.com/ds/2/475/93507100-253078.pdf
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