# Calculating Holding Current

1. Dec 23, 2011

### a2009

Hi All,

I'm designing an experiment and want to estimate the holding current (minimal current to maintain a spark) for my setup.

Does anyone know how to calculate the holding current? I imagine it should depend on gas mixture, pressure, temperature.

A reference to a book/article discussing this would also be very welcome.

Thanks a bunch!

2. Dec 23, 2011

### Staff: Mentor

Let's see how good my mind-reading skills are today. Are you wanting to maintain an electric arc in a pressurised inert gas? Which gas? What are the electrodes? Is this at high pressure or low pressure (cf. atmospheric).

In any case, I doubt that I can assist. But I'd say no one will be able to if you don't provide more details.

3. Dec 23, 2011

### a2009

Thanks for showing me the question wasn't clear.

I'm looking into resistive plate chambers, and am trying to get a feeling for how to design the resistivity of the plate.

In RPCs, like in Geiger counters, the detectors undergoes a discharge whenever a charged particle traverses the active area (loosely speaking).

I'm thinking of the discharge as the shorting of a capacitor. So assuming the capacitor is shorted, what resistor do you need to put after in order to have the spark die out. When looking through literature I came across the term "holding current" as being this value.

So to rephrase, I'm looking for some formula, that would allow me to estimate the holding current (to make sure I'm below it). Because I'm also deciding on the geometry I would need something in which I can plug in geometry, gas type, pressure, temperature and see what I get.

As a baseline I would like to work in something like Ne + Isobutane 95/5 at atmospheric and room temp. But this can change totally.

Mostly I'm looking for a reference describing what determines the holding current of an arc.

4. Dec 23, 2011

### Naty1

see here...I did not read it all,,,maybe some insights :

http://en.wikipedia.org/wiki/Geigerâ€“MÃ¼ller_tube

The resistor likely allows a voltage to be maintained so that discharge will occur when a particle is detected....when the particle passes and ionization of the gas completes, the current stops...that doesn't seem to depend on the resistor size.

Last edited: Dec 23, 2011