04-500 Old style X-ray source filament conversion

The very early PHI 04-500 and 04-548 X-ray sources used a small filament that had couplers to make the connection between the X-ray source and the filament.

04-500 04-548 old style filament

04-500 04-548 old style filament










In addition, the couplers were held in place with a notched ceramic that had a special pointed set screw which pressed into a copper wire that in turn made the connection to the electrical feedthrough on the source.










This connection scheme worked well enough as long as you set the filaments properly and did not ramp the current up too quickly.  Even then, the filaments were prone to warping out of shape over time.  Also the couplers could loosen up and then the filaments would short out.

PHI’s solution was to redesign the filament where the filaments were brazed into a ceramic base instead of using couplers.  This resulted in a very stable filament base where the filaments can’t move at all and so they no longer warped out of position (unless you ran the filament current up too quickly).

Recently I updated an older 04-500 X-ray source from the old style to the new style filaments.  You can see the before and after in the pictures below.

old 04-500

Old Style 04-500 X-ray source

new 04-500

Updated 04-500 X-ray source




















This update will result in more stable X-ray source operation and extended filament lifetime.

The new style filaments cost more than the old style filaments by quite a bit.  But factoring in the improved performance, longer lifetime and reduced downtime it may be worth the additional cost.

If you have an old style source please keep this filament conversion in mind the next time you need filaments or a complete source rebuild.

Contact RBD Instruments for more information.