New Fusor progress: up date

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Dennis P Brown
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New Fusor progress: up date

Post by Dennis P Brown »

Ran my new fusor (with the 'improved' HV feedthru) while using deuterium gas. I was able to create a stable plasma at 32 kV and 28 ma for the run and had zero control issues - that was nice for a change. The plasma "burned" steady without any hic-ups or current runaways or voltage drops.

I am convinced my TC and cold cathode's are a bit off - the plasma was extremely stable at these voltages and currents with the pressure reading 'only' 1.5 to 2 microns (the cold cathode agreed). In the past and for most people here, average sized fusors tend to run more in the 5 to 10 micron range. So, these two independent gauges have to be off and reading low in roughly the same manner (might try changing the calibration screw on the TC.) The cold cathode has no calibration controls that I am aware.

Ran the chamber for about seven minutes; the pressure at previous values was about 2.5 microns so the TC might need warming or still out gassing a bit. I detected no significant radiation (x-ray0 increase anywhere around the chamber via the detector. Tried both my scintillation and Geiger detectors. The chamber body got noticeably warmer but the HV feed shaft remained cool. That was a nice occurrence since that feed has the vulnerable epoxy seal.

I am running the turbo in standby mode since pressure control via the gate valve is easy; I use the gate valve to control overall chamber pressure (with an arbitrary D2 feed flow rate - I use about the number of turns on the unit I previously found using my original fusor) and then I use the D2 leak valve to precisely control the power supplies current.

All in all, a very successful initial trial run with no current runaways, pressure burps, voltage spikes or other issues related to the power input. Maybe something is wrong ... .
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Richard Hull
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Re: New Fusor progress: up date

Post by Richard Hull »

With a bright glow at the grid at 32kv and the rather outrageous current of 28ma I would think the pressure would indeed be a good bit higher. I would conclude, something is amiss somewhere. I have no suggestions beyond a check on the instrumentation. Got any photos of the glow and grid?? The grid ought to be near white heat and after operating at that level for 10-20 minutes the fusor shell should be at 100 deg C or more.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Dennis P Brown
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Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: New Fusor progress: up date

Post by Dennis P Brown »

The fusor body is too hot to touch but the grid is certainly not hot enough. Also, I have been concerned that the chamber plasma glow is too weak compared to my previous fusor. As you are pointing out the grid isn't getting the level of intense glow required for that power level (it is a dull red - far from white) - you are correct in that something is amiss.

I run the two HV transformer output leads into a full diode bridge. Then one side is the fusor power (of course, negative side) and the positive side of the bridge runs through a 30 K-ohm resister, then through a milliamp meter and that is grounded. I've check the voltage output directly but not under load - that will be my next task.

Checking the current by another method is tricky and I'm open to suggestions.

You can see some pics of the cathode at: viewtopic.php?f=11&p=94004#p94004

These were at 12 kV; the 32 kV wasn't much different - which is a flag in of itself, now that I'm thinking about it.

I will also add a KF port to my main chamber body - to directly measure pressure. I can borrow another pressure gauge to cross check that parameter directly on the chamber as well.

Thanks for the input Richard, valuable and helpful as always.
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Richard Hull
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Re: New Fusor progress: up date

Post by Richard Hull »

1. I assume the transformer is not center-tapped. If it is you are in a dangerous level of operation using a bridge.
2. The ballast needs to go in the negative hot lead.
3. Never take the positive of the bridge to ground through anything more than 10 ohms. Current is measured solely by the voltage across the 10 ohm, 5 ohm, 1 ohm or .1 ohm resistor in the ground leg.

That 33k resistor will make things dangerous if not deadly in the positive ground leg. Get it out of there. I assume this is the ballast? If so put it in the hot negative lead circuit path.

Take care of the above issues if they are present and your current and voltage readings might be OK, under real load conditions. Never use a DVM current meter mode in series with any of the high voltage lines. Use the DVM in voltage mode across the low ohm, grounded resistor.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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