Laser-Based Detection Of Highly Vibrationally Excited H 2 For Plasma Diagnostics

Abstract

It has been suggested that the main source of IV in hydrogen plasmas is dissociative attachment to H2(v≥4). In order to test models that include this process, it is necessary to measure the populations of the relevant vibrational levels inside the plasma. We have constructed a source of vibrationally excited H2 using a recently discovered hot-wire effect. Using 2+1 resonantly enhanced multiphoton ionization (REMPI) through the EF state, we have detected H2 in 27 bands from X(v"=4-11) to EF(v'=0-14). Rotational temperatures appear to be 300-800 K, well below that required for thermal excitation of the observed vibrational levels. The population of vibrational levels appears to fall off dramatically between v"=9 and 10.