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double field ion-trap
I checked the ion-trap. It has a field of 38 Gauss, slightly more than the specified 35.
I'm a bit puzzled about the physics of a double field trap if anyone has light to shed on them. I was expecting "a double field." Instead it seems that the narrower pole pieces clamp the fringe field so that it doesn't extend beyond the wide pole on the bulb side.
Although the marks on the CRT indicate that the trap hasn't been moved in many decades it appears that it might have been maladjusted. It open end wasn't pointing directly towards the anode. It was also much farther back towards the base of the tube. This would make sense if the magnet was weak, but since it's a little stronger than spec and the CRT is run at 7.5KV instead of the 9KV that the 35 Gauss was specified for, I would expect it to need to be closer to the bulb. But, reality doesn't always seem to listen to theory.
John
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