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: Bell Jar
Date: Oct 22, 3:10 pm
Poster: Richard Hull

On Oct 22, 3:10 pm, Richard Hull wrote:

>Hello I found a bell jar with a guard the vacume rating is 28.5 " of mercury. How do you convert inches of mercury to torr? since standard atmospheric pressure is 29.92 that seems to leave
>a whole lot of air in the bell jar.



The standard atmosphere is taken as 760mm of mercury or 760 torr. 1 torr=1mm of pressure.

If that bell jar won't handle pressures lower than 28 torr, then it isn't worth beans!..., (the math...28.5" X 25.4 = 732mm or 760-732= 28 torr)

How big is it? Is it pyrex, kimax, or other brand of borosilicate glass?

If it is not borosilicate glass you should never use it for a fusor demo. Needless to say, you should not attempt real fusion in a bell jar period. Care must be exercised with glass chambers. Implosion guards are a must and short demo runs are the rule.

Some flint or soda glass bell jars are designed for simple physics experiments, (bell ringing in a vacuum, dessication, etc) and not plasma experiments.

The fact that your jar is rated in inches shows its age.

Richard Hull