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: Foreline traps
Date: Oct 01, 09:45 am
Poster: Richard Hull

On Oct 01, 09:45 am, Richard Hull wrote:


Those who are extremely serious about the fusor and who want to raise their voltage, will ultimately have to hit single digit micron levels in their fusors.

To do this with a common mechanical pump you will almost certainly have to employ some kind of foreline trap.

A foreline trap is usually a molecular seive type of device and traps out backstreaming oil vapors from the hot mechanical pump and water vapor from the fusor chamber.

This is yet another expense, but must be considered by the enthusiast who needs 1-3 micron vacuum levels, yet doesn't wish to set up a diffusion pump arrangement. (note** even a diffusion pump system will benefit tremedously from the use of a foreline trap.

A foreline trap is not a solution for filthy or contaminated pump oil!! Change out pump oil regularly!!! The foreline trap is placed between the mechanical pump and the fusor chamber. The foreline trap has a heater which can be used to purge the trap as it slowly builds up trapped contaminants. The purging is an operation which must be done in a specific sequence to avoid contaminating the fusor. It is easy provided attention is paid to the manufacturers instructions and a good valve is provided between the trap and fusor.

I have seen the Kurt Lesker "micromaze" trap in action and it is superb and a lot less messy than other foreline traps. I comes with intergral pruging heater. It costs about the same as other traps considering the cost of the other traps and required zeolite fills. (approx $300.00).

More vacuum info to chew on.

Richard Hull