Mark II prime, Bob's fusor, The AEC demo fusor

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Richard Hull
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Mark II prime, Bob's fusor, The AEC demo fusor

Post by Richard Hull »

The question has been asked why Gene Meeks mark II prime fusor was so much better than Bob Hirsch's fusor, etc.

I will attempt to explain.

There are only three real fusors of the ITT effort which were runaway sucesses compared to all previous units.

One was the AEC demo, another was Bob Hirsch's fusor and the other, Gene Meeks Mark II Prime.

The AEC fusor was a gunless device which I refer to as the Hirsch-Meeks device and is the subject of the 70s patent they shared together. It used D-T and could achieve 3X10e7 n/sec total emission. It used a circular, hot cathode electron emitter and a secondary ionizer grid.

The Mark II prime and the Bob Hirsch's fusor were both ion gunned systems. Both were D-T fusors.

Bob's fusor was in the cave and can be seen in the image I uploaded. He had a couple of iterations of the device, but the most he ever got was on the order of 10e10 n/sec, total isotropic emission. He used a differentially pumped gun system. (The guns were pressurized @ ~10 microns <10e-2 torr), compared to the fusor body which was normally held at 10e-6 torr. Gene notes that this caused the deuterons to "explode" into a spray the moment they entered the chamber through the injector cones. This, he felt, limited Bob's ion currents and destroyed the beams somewhat.

Gene's Mark II Prime produced a prodigious 10e13 n/sec. It used guns open to the chamber and at the pressure of same. (~5X10e-3torr) Add to this, the fact that Gene was using what he called a "re-entrant" aluminum hollow cathode. (They never used grid wires except in the Hirsch-Meeks device.)

This cathode had tubes (one per beam entrance) which whould reduce the anode field affecting the secondary electron emission within the cathode structure. This reduced the current losses to the anode and also limited the X-ray production. (all loses).

Spangenberg speaks of this in his many books on electron tubes. Basically, if you have a 3cm hole in a closed tube element, (In this case the hollow cathode), then placing a 3cm long tube in the hole will shield all fields outside of the open device, electrostatically. Thus, secondary electrons within the cathode structure could not see the anode shell and thereby create a loss current to same which can produce copius X-radiation.

Gene felt his system got more ions to the center and reduced energy losses. His was the last machine to be assembled in Fort Wayne before termination of the project. When he left, it was still on the vacuum stand. It has strangely disappeared, being the only Farnsworth fusion device whose whereabouts or fate is unknown.

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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Re: Mark II prime, Bob's fusor, The AEC demo fusor

Post by guest »

Thats an interesting modification Gene had by using tubes on the cathode openings, I wonder if the sheetmetal cathodes that Daimler Chrysler have on their fusor or the unit Dan Preston had made would have a similar effect?.

Mark Harriss
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