Metastable chlorine ion temperature and drift velocity in an inductively coupled plasma

Laser-induced fluorescence has been used to measure the temperature and radial drift velocity of metastable chlorine ions in inductively coupled Cl2 and Ar/Cl2 plasmas. In the center of the plasma, the Cl metastable ion temperature varied between 1500 and 3200 K for rf powers between 200 and 400 W and pressures between 7 and 30 mTorr. Increasing the chlorine fraction in an Ar/Cl2 gas mixture from 10% to 100% increased the Cl metastable ion temperature from approximately 1500 to 3200 K. Spatially resolved measurements of the ion temperature indicated that the ion temperature increased to between 4500 and 5500 K at the edge of the discharge and increased approximately 700 K moving from the rf source toward the lower electrode. Ion drift velocity in the radial direction was between 6×104 and 8×104 cm/s at the edge of the plasma. Implications of these measurements on the Ar/Cl2 chemistry and the energy transport in the plasma are discussed.