P47 Scintillator tests on the ion beam

Tests were performed on the sensitivity of a P47 scintillator disc to the ion beam and plasma. The disc was mounted ~100mm after extraction, with a 90cm expansion distance to the extraction region. The average extraction ion current under these conditions is around 100mA for 5us.

With just the expanding plasma measured, the light from the disc was faint (as measured with an image intensified CCD camera, with 1us integration - the minimum). After applying an extraciton potential of 80kV, a very strong signal could be seen, not requiring any intensifying from the CCD camera (and the lowest ADC gain).

Below are shown images measured for similar extracted currents, at different delay times. From right to left, then top to bottom the integration times for each shot are 0-1us, 1-2us, 2-3us, etc. Care must be taken to compare the times to correct elements in the plasma. Hydrogen for example arrives at ~1us, while the highest charge state tantalum ions start to arrive at 2.5us.

The hole in the beam is due to the damage on the screen, which happened after a couple of shots. This should be avoidable in the future by decreasing the density (either with a mask, or after some selective focussing elements).
back to home... prepared by Richard Scrivens February 1996