Emission spectroscopy of dipolar plasma source in low pressure hydrogen
Résumé
Method of emission spectroscopy was used to study the plasma
characteristics of the dipolar plasma source [1] in hydrogen at pressures 0.001 –
0.01 Torr, microwave power 200-1200 W, microwave frequency 2.45 GHz.
Spectral composition of plasma emission was investigated in the range of wave
length 601–627 nm. Functions of distributions over rotational (J=1–5) and
vibrational (v=0–2) levels were determined for excited state d3П-
u of hydrogen
molecules. Gas temperature Tg, rotational Trot(d3П-
u) and vibrational Tv(X1+
g)
temperatures were determined on the basis of collisional-radiative models [2-4].
It was found that the distribution function for the lower rotational levels of
H2(d3П-
u) is Boltzmann distribution. Temperature Trot(d3П-
u) changes in the range
205–325 K. The distribution function for the lower vibrational levels of H2 in the
excited state d3П-
u differs from the Boltzmann distribution. The magnitude of the
vibrational temperature is 3100400 K, translational temperature is in the range
420-650 K. The obtained values of Tg and Tv(X1+
g) suggests that the
discharge at low pressures in hydrogen is an effective source of vibrationally
excited hydrogen molecules.
This study was supported in part by RFBR grant # 15-08-00070.