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# Xenon lamp ignition sequence

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#### tnnedaboard

##### Member level 3
Hi,
time ago I studied the ignition circuit of a Xenon lamp (see attachments) I wanted a last information kindly, on power-up sequence:

1. Load the capacitors to a certain voltage (max 300Vcc)
2. sending the capacitor voltage across the lamp
3. active discharge trigger (lasting from 10 to 30ms) to get the lighting of the lamp

is' the right sequence?

The duration of the ignition of the lamp is equal to the duration of the discharge trigger?

View attachment P3295 VI.pdf
View attachment CP3295 Issue B.pdf

Try again

>18kV min for trigger >0.62us .. choose a few us
with Cap 540V~1889V for reliable trigger

With only 300Vdc on cap, trigger must be increased.

Duration of lamp depends on size of capacitor & voltage , as lamp is a negative resistance avalanche with an positive power series ESR where Impedance parameter. (Ko) 11.9 Ohm Amp ^0.5

ESR of cap. & lamp limits current ~ 2kA max

thanks response

but the ignition sequence is correct?

Do you understand ignition is due to dielectric breakdown in Xenon under 1/2 A pressure?
Breakdown threshold increases with rise time, thus >>18kV is needed with 450Vdc and with no pulse 2kVdc is needed
With no DC, much higher Impulse voltage is needed and for 300Vdc somewhere in between.

When ignition, or detonation or dielectric breakdown occurs, like ESD or lightning or any gas tube discharge lamp, reaction time due to negative resistance of ionization, is fast.

ESD for example in a small gap like Partial Discharge in oil in a power transformer only has 10 ps rise time due to small local inductance inside the dielectric.

Thus trigger only ignites and follow-on voltage drops quickly to low impedance capacitor voltage and high current sustained for RC time constant except R is non-linear and is inverse to current so R*A^.5 is constant. ( Faraday discovered this )

So sequence is simple, trigger then follow-on voltage with current.

holding current depends device when it goes below this, the impedance rises instantly , as detonations stops and residual voltage is left on Cap.

The same is true for SCR's which has negative resistance and holding current. with low voltage trigger.

ok,

so if rather than wait for the lamp to turn off when the capacitor voltage falls below a certain level,
I wanted to have ignitions of X milliseconds after ignition, just remove the voltage across the lamp at a given period T (ms) Default?

that's right?

:grin::thumbsup:

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