Making Hydrogen with PEM cell

[Chuck Sherwood]

I ordered a PEM cell kit from Joe for the purpose of testing the output in my home made mass spec.
I started by holding all the items in clamps on a lab stand. This worked but was quite awkward. I used a glass syringe because the large plastic one was pretty sticky. A glass one with a tiny bit of vacuum pump oil lubrication works quite well. I used a lab supply so I could see the current consumption which varies all over the place. I have seen it over an amp but typically it runs about 1/4 amp.

For the first run I used distilled water and captured the H2 and sucked it into my system like this. The plumbing is pumped out and the entire volume is sucked into the empty plumbing between a pair of valves. A tiny amount from the trapped volume it allowed to leak into the main system trying to keep the pressure in the low 5s.

Hydrogen generated from distilled water produces this trace. The purple line is the magnetic field measured with a Hall sensor. Yellow is the electrometer output. There is a small peak for H1 which is always present to some extent and is produced by frackin of H2O in the system. The large peak is H2.

A wider scan shows water vapor present but its always present and not noticeably larger than without the sample gas. Another important fact is that H2 has an ionization value of 0.42 comparted to N2. So the H2 response is less than half was most other gases would show at the same pressure.

[Chuck Sherwood]

I decided to improve the PEM cell setup. I made a small brass bracket to hold it vertical and modified a lab stand by adding a couple rods so I could clamp all the pieces in a straight line.

My bottle of deuterium oxide as received and anchored so it cannot be spilled.

This setup works quite well

I made some hydrogen using the heavy water in the kit. The spectrum is not exciting. It starts with a small H1 response which is always present. A large response at AMU=2 which could be H2 or D1. Since it is made from heavy water, I would assume D1.
Notice a small response at AMU=3 and also a small response that is hard to see on this trace at AMU-4.

All and all an interesting experiment.
cs

[Chuck Sherwood]

Here is a trace with the emission and cranked way up. It shows AMU 1-3 as large peaks with 2 saturated. There is a small blip on the right hand side for AMU-=4 which I believe is two D2 atoms.

[Richard Hull]

Excellent report with images. Superb effort and thanks for sharing this interesting data with us.

Richard Hull

[Joe Gayo]

Curious. Normally, D2+ is the most common species due ionization cross section. What are the parameters of the ionizer?

[Chuck Sherwood]

I expected a lot more mass 4 in the trace as well.

My mass spec is based on an old VeeCo leak detector. Most of the info is in this thread.
viewtopic.php?t=13905

The ion source is driven by this power supply
download/file.php?id=26379&mode=view

In review the anode of the source is biased at 75 volts, the repeller grid about 12 volts higher.
Do you think there are better parameters? I have not changed this values in quite some time.

The deflection voltage to accelerate the ions around the magnetic sector is set to 250 volts for this test which ties in with the magnetic field.

cs

[Chuck Sherwood]

It dawned on me that I had previously used distilled water for the baseline test to produce H2 the day before. I removed all the water but I suspect the membrane was still saturated with regular water. So I collected some more hydrogen and purged it a bit too. Here is a new trace showing AMU 1-4 from left to right. The presence of AMU 3 indicates there is still significant regular water in the mix but the large AMU 4 clearly shows lots of D2. I suspect a third run would show even more D2. Thanks very much for the feedback.

[Chuck Sherwood]

I did another gas collection for a total of 3. Keep in mind, I'm only collecting 20 ml at a time. Here is a scan showing AMU 1-4 from left to right. 4 is now the largest peak as the regular water is flushed out of the PEM cell. Its been interesting!

[Richard Hull]

We live and we learn from your effort here. Thanks.
You ran the distilled water as a base line. Wise to do that in relation to your mass spec. work.

We now know to never run distilled or tap water through a Pem cell without doing 3 or 4 wasteful heavy water runs to clear the cell.

The lesson learned:
If you are only doing fusion and value having only D2 in your fusor, only run heavy water through your PEM cell for as long as you own it.

Again, this is all very good info.

Richard Hull

[Bob Reite]

When I got my first PEM cell I debated running ordinary water through it for test purposes, but decided against that because I had no idea how many purge cycles it would take to get rid of the normal water, so I started straight off with heavy water.