Hf start gets used because 32 Kv PIV 2 Kiloamp diodes with no forward drop only exist in Star Trek plasma conduits. ;-)
Lift start does a great job of ruining your carefully shaped Tungsten TIG tips, and they can get stuck in the weld at start when doing it by hand.
I have Xenon Arc lamps, Ion Lasers, Pulsed Flashlamp based lasers , and welders in my life. All but one device uses either HF start or a cap dumped into a coil to make a 100 Khz or greater exponential decaying AC start pulse.
Cap dumped systems usually have a serloies injection ignition transformer that carries the whole load current, a series inductor to block the RF and a specially constructed metal canned mica capacitor across the power supply to protect it by providing a return path for the RF. Many of these devices have spark gaps to keep their DC supply out of tbe HF starters. All the cap dumped systems depend on the plasma voltage clamping and adsorbing the ignite spike to protect the PSU. If the plasma doesn't form in many of these devices, the psu and /or any blocking diode is toasted.
Most of the non welding devices have DC boost voltages across the load to aid in Cathode Spot Formation.
The pulsed flashlamps have series ignitors, 3 KV 100 mA simmer currents and IGBTs, SCRs, or Thyratrons to dump in the capcitor into the ignited load.
IF dc start were practical for loads above 100 mA most of these devices would have it.
Hf start toplogies work, are proven, act as their own load switch for pulsed loads, do not need exotic diodes and the ringing wave creates very high peak fields. Lc filters do a great job in place of expensive diodes.
The one DC started lon Laser I have results in hard starting plasma tubes that get replaced early. The same tube that gets removed lives another few thosand hours if placed in tbe same model laser with HF start installed.
Steve
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