Plasma emission and absorption spectroscopy with an optical fiber probe

Summary Form only given, as follows. An optical-fiber probe has been used to measure the emission and absorption coefficients of a parallel-plate RF plasma. The probe, made of crofon, is inserted into a glass tube filled with air at atmospheric pressures in order to prevent the initiation of a discharge by the RF capacitively coupled inside the tube. The probe end of the glass tube is designed as a half-lens for focusing. The advantage of the probe is its capability to make localized measurements, allowing three-dimensional mapping of the emission and absorption properties of the plasma. The experiments were carried out in a parallel-plate reactor which was used for sputtering Y-Ba-Cu-O superconducting thin films. Measurement of an RF glow discharge with an electron density approximately=10/sup 10/-10/sup 11/ cm/sup -3/, electron temperature approximately=1.0 eV, neutral pressure approximately=115 mtorr, and RF power of 30 W at a frequency of 500 kHz gave values of alpha =2.2*10/sup -2/ cm/sup -1/ and epsilon =9.2*10/sup 6/ for lambda =6166 AA. Theoretical calculations indicate that the absorption coefficient of the bremsstrahlung radiation is much less than the measured alpha value.<>