Interesting NPR data from ring accelerator fusor

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Rich Gorski
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Real name: Rich Gorski
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Interesting NPR data from ring accelerator fusor

Post by Rich Gorski »

Hi Everyone,
Below is some interesting NPR data taken from my fusor using two circumferential ion sources at 1 micron D2 gas pressure. At this low pressure no ionization occurs in the chamber up to at least 40kV until the ion sources are energized. This means that I have independent control over both the ion current and the negative high voltage. Taking advantage of this feature I have performed two tests looking at the neutron production rate (NPR) as a function of voltage and current.
1) Constant ion current at 10mA while varying the kVs from -15kV to -40kV
2) Constant -35kV and varying the ion current from 2mA to 20mA.

The data indicates what we would expect. A linear dependance of the NPR with ion current at constant kV and an exponential dependance of the NPR with kVs at constant ion current. The linear dependance of NPR with current is expected since increasing current increases the number of D2 molecules available for interaction in a linear fashion without changing the ion energy or reaction cross section. The dependance of NPR with kVs should go exponentially since changing the negative accelerating voltage changes the ion energy and thus the fusion reaction cross section which increases exponentially with energy.

The Excel plot below shows the results.
IV-ring.jpg
Another interesting feature of using ion sources at low pressure is that I can operate the ion sources in a pulsed mode at a given duty cycle. In this test the ion sources were running with a 25% duty cycle (0.5s on 1.5s off). During the off period and with constant negative high voltage applied the PSU current was zero since at this pressure no ionization occurs in the chamber. The ion sources can be energized with a discharge voltage of 500 to 1000V to produce anywhere from 2mA to 20mA total ion current as registered on the main negative PSU. This also has the advantage of reducing the total power going into the chamber keeping it cool as well as reducing the X-ray and neutron dose absorbed by the operator. In this set up a pulse generator provides a the pulse signal to a simple mosfet circuit which energizes a reed relay to turn the ion source discharge voltage on and off. The contacts in these small relays can handle 1000V at 1A and the coil to contact isolation is good to 4kV.

I though this data would be an interesting confirmation of the expected results (theory ?) especially since in the standard fusor one cannot separate the current from the voltage.

Rich G.
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Richard Hull
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Re: Interesting NPR data from ring accelerator fusor

Post by Richard Hull »

Good data presentation with all of the parameters well handled that seem to verify the expected result. Nice work.

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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