TY - GEN
T1 - Cavity ring down detection of neutral hydrogen atoms and negative hydrogen ions in plasmas
AU - Boogaarts, M.G.H.
AU - Smets, A.H.M.
AU - Sanden, van de, M.C.M.
AU - Schram, D.C.
PY - 1999
Y1 - 1999
N2 - The Cavity Ring Down (CRD) technique has been applied for the absolute detection of low density species in two different hydrogen containing plasmas. CRD measurements have been performed in a 10 Hz pulsed capacitively coupled RF H/sub 2/-plasma to detect negative hydrogen ions (H/sup -/) as well as atomic hydrogen in the n=2 state (H(n=2)). A broadband absorption of 3.5*10/sup -6/ per pass due to photo-detachment of H/sup -/ was observed, which corresponds to a H/sup -/ density of 10/sup 16/ m/sup -3/. In addition, CRD measurements on H(n=2) have been performed in the expanding plasma of a cascaded arc, in which H/sub 2/ or C/sub 2/H/sub 2/ is injected. Densities of H(n=2) down to 10/sup 12/ m/sup -3/ have been measured. In both plasmas a severe decrease of the reflectivity of the cavity mirrors over time was observed, which is possibly caused by diffusion of atomic hydrogen into the reflective coating
AB - The Cavity Ring Down (CRD) technique has been applied for the absolute detection of low density species in two different hydrogen containing plasmas. CRD measurements have been performed in a 10 Hz pulsed capacitively coupled RF H/sub 2/-plasma to detect negative hydrogen ions (H/sup -/) as well as atomic hydrogen in the n=2 state (H(n=2)). A broadband absorption of 3.5*10/sup -6/ per pass due to photo-detachment of H/sup -/ was observed, which corresponds to a H/sup -/ density of 10/sup 16/ m/sup -3/. In addition, CRD measurements on H(n=2) have been performed in the expanding plasma of a cascaded arc, in which H/sub 2/ or C/sub 2/H/sub 2/ is injected. Densities of H(n=2) down to 10/sup 12/ m/sup -3/ have been measured. In both plasmas a severe decrease of the reflectivity of the cavity mirrors over time was observed, which is possibly caused by diffusion of atomic hydrogen into the reflective coating
M3 - Conference contribution
T3 - LRP / Ecole Polytechnique Fédérale de Lausanne
SP - 215
EP - 218
BT - Frontiers in low temperature plasma diagnostics III : book of papers ; Saillon, Switzerland, 15.-19.2.1999
PB - Ecole Polytechnique Fédérale de Lausanne
CY - Lausanne
T2 - Frontiers in Low Temperature Plasma Diagnostics III, February 15-19, 1999, Saillon, Switzerland
Y2 - 15 February 1999 through 19 February 1999
ER -