Circuit measurement of electron emission

Apologies for any misunderstandings of fundamentals. I'm new at this.

I am interested in testing an hypothesis that a particular gas contains a negatively ionised constituent. If this is the case, then it would be reasonable to assume that the electrons added to the gas come from the electronic circuit that produces the gas. This would be an example of consumption of electrons by a load, or perhaps more properly, emission of electrons out of a circuit.

I imagine this is by no means a novel concept. Any electron beam would entail the same thing, I would think. My question is, how do I measure it in the circuit? Effectively, I need to count the electrons in the circuit before and after the gas process. A reduction in the number of electrons (not merely a reduction in their potential) over the load would support the hypothesis that the gas has a negatively ionised constituent. I would imagine it would be a cheaper and more accessible way of measuring than to do a gas analysis. Surely there is an established process for this kind of metric?

by Puck
November 15, 2017

Interesting hypothesis. Of course the emission of electrons in large quantities occurs in vacuum tubes such as valves and crts, but this is from a rare earth cathode heated and in vacuum, and the electrons are attracted by positively charged electrodes. The sort of emission postulated would be very much smaller and a one-off event rather than a continuous current. This is one of the most difficult things to measure, charge rather than current, and if you wish to take the difference between two quantities this presents further problems of accuracy, since the quantities will not have sufficient accuracy for subtraction. I would definitely hesitate before approaching such a problem. Are you able to put numbers on the amount of current or charge involved?

by mikerogerswsm
November 16, 2017
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Answer by Puck

The gas is continuous flow, so it's not a simple charge-transference. I naively imagine this could be measured by current, but the resolution required may well be finer than error, especially when fluid dynamics are involved. I do not imagine electrons are being emitted in great quantities; the biggest clue is that the gas, when ignited, exhibits a significantly larger potential difference over the flame than other flames tested. Up to 2V for a flow of ~7L/min.

There are a number of units producing the gas, with different parameters. The above example runs at 120A over several cells.

I wonder if, alternatively, there might be ways of testing the hypothesis by 'wiring' a circuit using the flame as the power source. It's messy, as there is heat involved as well as current flow, but the flame applied to a conductive material should be capable of introducing the hypothetical ionised-gas electrons into a circuit. A circuit could be constructed with the negative terminal on the gas nozzle, too, as per voltage measurements.

This all needs to be very low-tech, mind. Although I am open to high-tech suggestions for future research opportunities. Still, it always helps to have preliminary results to justify the expenses involved in playing with the big toys!

+1 vote
by Puck
November 16, 2017

Glad it's continuous flow, that makes measurement a little less difficult. I might suggest using an electrically isolated grid of gold or platinum inserted into the gas flow. By running this at say +100 volts with respect to the gas nozzle, it would 'collect' most of the electrons, which then could be measured as a current. The voltage supply should be 'floating' with no stray currents and the current could be measured on the ground or nozzle side using a series resistor and dc amplifier. Is this practical within your equipment?

by mikerogerswsm
November 16, 2017
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