Simultaneous measurement of the hydrogen isotopes H, D, T and 3He with HIERD

Abstract

The most straightforward method to measure simultaneously the amount and the depth distribution of different light atoms trapped in the surface layers of a solid, such as needed in investigations of the plasma-wall interaction in controlled thermonuclear fusion research, is the heavy ion elastic recoil detection (HIERD) technique. This technique has been applied using 30 MeV 35Cl ions to measure the light ions collected in a Ti target and in C targets. The recoiled atoms have been identified and detected by a ΔE − E telescope consisting of a 14 μm transmission detector and a SSB detector with a 12 μm Al foil at the entrance to stop all heavy ions. The hydrogen and helium isotopes are clearly identified. The sensitivity of this technique is the largest for H and decreases proportional to Mr3 i.e. proportional to 8 and 27 for the two heavier hydrogen isotopes, while the depth resolution is the best for tritium. Recoils heavier than He up to sodium are simultaneously detected by a Bragg ionization chamber.