Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Where can I get an ion gun???
Date: Jul 15, 11:59 pm
Poster: Richard Hull

On Jul 15, 11:59 pm, Richard Hull wrote:

>Where do you get ion guns?
>Do they have to be made or can you buy them?
>If so where?


I didn't mean to lay down negative vibes on the ion gun. It just seemed a needless appendage if one is just out to do fusion.

Hector in his post on this topic is correct. Yes, you can buy them and some few are in the El Cheapo range of $5,000 each, but the real he-man rolls his own just like cigarettes.

The ion gun is just a modified electron gun with a chamber for admission of the gas (D2). Within this chamber the gas is ionized by copius amounts of electrons from a filament. The unsuccessful and wayward electrons are captured by a grid while the deuterons are accelerated and focused with ion optics not too far removed from a CRT electron gun system. The difference is that the ion guns, traditionaly, are run at elevated pressures (1-10 microns and a tiny hole allows the deuteron beam out of the gun into a much deeper evacuuated chamber (often in the 10-7 range). This action demands critical differential pumping and incredibly complex vacuum systems.

A simple fusor with ion guns doesn't necessarily need too complex a diff pumping system, but would still be an incredibly complex overall assembly for the rank amateur. I would consider, as Farnsworth did, four guns a bare minimum with 8 preferred.

Farnsworth's ion guns were designed mainly by Meeks who was especially adept at this work. He an I have talked at length about them. Hirsch noted to me that Gene "had the best pair of hands on the team". It will be remembered by those in the know that the Fort Wayne ITT facility was almost totally dedicated to the production of ultra special DOD and government use vacuum tubes.

ITT had a huge chemistry and coatings lab, model shop, spot welding facility and a vacuum system in nearly every room! Cyril Day was their best tube design engineer and he transfered a lot of his ion gun knowledge to the then young Gene Meeks in 1959 and 60.

Books on ion optics will give some insight into ion gun design, but befudle with complication far beyond the need and purse of the average fusorite.

Richard Hull