How Do You Calculate Holding Current for a Spark?

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Discussion Overview

The discussion revolves around estimating the holding current necessary to maintain a spark in resistive plate chambers (RPCs), particularly in the context of gas mixtures, pressure, and temperature. Participants explore the factors influencing this current and seek references for further understanding.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Adam seeks to calculate the holding current for maintaining a spark, suggesting it depends on gas mixture, pressure, and temperature.
  • Another participant questions the clarity of the initial inquiry, asking for specifics about the gas type and pressure conditions.
  • Adam clarifies that he is focused on resistive plate chambers and relates the discharge process to the shorting of a capacitor, seeking a formula to estimate holding current based on various parameters.
  • A participant provides a link to a Wikipedia article on Geiger-Müller tubes, suggesting it may contain relevant insights, although they express uncertainty about the resistor's role in maintaining discharge.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specifics of calculating holding current, and multiple views regarding the necessary details and factors influencing the current remain. The discussion is unresolved.

Contextual Notes

Participants note limitations in the initial question's clarity and the need for more specific details regarding the experimental setup, including gas type and pressure conditions.

a2009
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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!

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

http://en.wikipedia.org/wiki/Geiger–Müller_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.
 
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