Microcurrent plasma tube

As far as I know, there is no lower limit for ionization save one particle. Meaning one electron should be sufficient, provided sufficient voltage. There are Neon indicating lights the mentioned size. They operate above 80V or so. What do you intend to achieve ?

Rene

In order to get a reliable light output, you have to start an avalanche. Individual ionization events are stochastic, so unless you give the bulb a decent kick, you're likely to get nothing whatever (not even one photon) much of the time.

Charging a small capacitor to, say, 100V and discharging it through a neon bulb would be one simple method to get a reliable low-amplitude light pulse.

On the other hand, LEDs are very much more efficient as well as much easier to drive from batteries. What are you trying to do?

Cheers,

Phil Hobbs

I used to do low current discharges for a living, which gas, what fill pressure, and what do you want to do?

This is way out of date, but interesting reading. Please note the electronics are 50s-60s era and not of much help to you, things are much easier today.

Steve Roberts

for example, at currents under 1 ma, a standard small xenon tube from a disposable camera has a 2.2 KV breakdown voltage, is 2 mm diameter and 20 mm long, but has a arc instead of a brush plasma. The other question is how short a pulse of light do you really need? Do you need 100% extinction? The 4 AA part is easily doable.

Steve Roberts

On a sunny day (Tue, 02 Dec 2008 08:42:03 -0500) it happened Phil Hobbs wrote in :

I once, in a moment of ignorance, tested a 1kV capacitor bank by putting a neon across it. The bulb had double glass, the inside glass exploded. I was lucky. Neon has very low impedance when ionised, huge currents can flow. Use a series resistor. Or a real stroboscope bulb with the right voltage.

neons make great current sensors for nanoamp currents in high voltage systems. We had a application where we needed to measur 1-1000 nanoamps at 2-30KV in the university lab and the sensor had to float. One NE2, one plastic fiber, a photodiode and a logamp, instant curent sensor. I think we stopped calibrating at .01 nanoamp, but it could go well below that if you used a PMT or held the photodiode temperature constant. Calibration was against a Keithly pico amp meter

Steve Roberts

neon across it.

It's not a problem if you keep 6-10 times below the explosion energy (that's actually how flash lamps are specified). When I said 'small', I meant like 100 pF at 100V. You couldn't explode a fruit fly with that.

Cheers

Phil Hobbs