Date: Fri, 27 Aug 2010 09:01:07

Author: Steve Anderson

Subject: Re: PASCO charge-to-mass ratio apparatus


> Dave, you might have some problems with atomic diffusion
> by running a constant DC potential at the higher temperatures
> of the wire, which might result in premature burnout of the
> filament, but calculations need to be done to see if this
> is a problem or not.
> -- Steve W.

Yes. This was a consistent problem we had using the ribbon filament
with DC (2-3 A). Using the Uchida (Pasco) e/M tubes with 6 VAC, we
lost any filaments for over 6 years, and they have a finer, more
visible beam.

The ribbon filaments would detach from the posts
(thinnk it was on the cathode end?).
You could see a heat gradient across them, with a visible-blocking

S. Anderson

From Fri Aug 27 14:26:18 2010