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: Getters, and conflat flanges
Date: Oct 13, 2:50 pm
Poster: Jonathan Smick

On Oct 13, 2:50 pm, Jonathan Smick wrote:

I am in the process of getting together the stuff needed to make a fusor. I'm going for stainless steel spherical construction w/ a Tantalum inner grid (I want the unit to be capable, eventually, of neut production, once I get past the "demo" phase). One thing I lack is a good vacuum system; right now (don't laugh!) all I have is a salvaged AC rotary compressor. I was wondering how much better (deeper) of a vacuum I could get (maybe at least enough for "demo" mode???)if I used a getter after pumpdown/bakeout, and what would be the best getter material(s) to use. And even if I had a "real" vacuum system, how much better would I do w/a getter vs. without?
Also, I was wondering if it is really necessary to use two hemispheres w/ conflats rather than a complete sphere; seems to me it would cost a LOT less as well as be better to use a closed sphere (no conflats to join the two halves, less to buy and less to potentially leak!) Reason I ask is that after seeing all the various designs out there on the web, it seems no one has done it this way; one unit I saw had the two hemi's joined by flanges (Richard Hull's??). As beautiful as that unit was, wouldn't it be OK to use a complete sphere, put a "modified sparkplug" feedthru on one side for the HV and a nice, thick Pyrex window on the other for observation (yeah, I know the window will of course need flanges, but they are small, and it would need them anyway w/the "hemi" design, PLUS that would of course need the two BIG, EXPENSIVE joiner flanges). This way I eliminate a BIG part of the expense (so I can save up for a better vacuum system instead!!!)