Re: Xenon Short Arc Igniter Help? (fwd)

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Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Mon, 21 Feb 2005 01:28:37 -0500
From: Charles Brush <cfbrush@xxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Xenon Short Arc Igniter Help? (fwd)

>Original poster: <sroys@xxxxxxxxxxxxxxxxx>
>
>
>
>---------- Forwarded message ----------
>Date: Sat, 19 Feb 2005 12:04:35 -0700
>From: robert heidlebaugh <rheidlebaugh@xxxxxxxxxxxxxx>
>To: High Voltage list <hvlist@xxxxxxxxxx>
>Subject: Re: Xenon Short Arc Igniter Help?
>
>Charles:NO ...The trigger is not in series. The trigger may be an isolated
>circuit or parallel. The main power supply may be a low voltage with high
>current. The voltage may be to low to ionize the gas and usualy is. That
>voltage can be from 20 to 500 volts but with a capacitor to provide the
>current. The trigger is usualy of high voltage to start ionization, but of
>very low current usualy only a few Milliamps through a high impedance
>resistance or coil like the resistor built into a spark plug. When the
>circuit fires the voltage drops to zerow preventing a power arc. Even carbon
>wires can be used. The trigger may be a sharp wire inside the flash lamp or
>a contact wire on the outside of the flash lamp requiring very high voltage
>to ionize the gas through the glass wall usualy around 30 Kv. In multi
>element flash lamps there may be up to 9 triggers to ionize the gass in
>stages to make a longer flash duration. In WWII the flash lamps used 450V
>one faraid capacitors to supply the current. A man at Mc Clellan AFB in
>California short circuited one with a wrench and vaporized the wrench and
>lower portion of his arm. The main power supply has high current. The
>trigger has low current of only 3 to 6 ma.
>      I hope this helps
>    Robert   H
>
>--


Robert,

I think we are discussing two different beasts here.  This is a 
typical xenon short arc lamp, not a flash lamp.  It has two main 
electrodes, with no trigger electrode or external trigger wire. 
Certainly similar to a flashlamp in many regards, but the hv trigger 
pulse basically has to travel the same path as the sustaining 
current.  According to what I've read, after the trigger creates an 
ionized path an intermediate supply dumps a capacitor charge across 
the gap to initiate the arc (like a strobe).  Then the low voltage 
supply (20 volts at 40 amps in this case) can sustain the arc on its 
own.  Sort of a three stage process in getting the arc going.


Charles