| 摘要 |
PROBLEM TO BE SOLVED: To measure time rate of change for the ion density of plasma. SOLUTION: A light-transmitting measuring window 106 is provided in the sidewall of a discharge vessel 100. A condenser 112 is disposed outside the measuring window 106 and introduces light in the discharge vessel 100 into a light transmission path 113. The light transmission path 113 branches into two in the middle, and the ends of the branches are connected to band-pass filters 114a and 114b respectively. The transmission wavelengths of the two band-pass filters 114a and 114b are different from each other, and emission lines of atoms of the same sort and emission lines of ions are transmitted thereby selectively respectively. With light intensity detectors 115a and 115b connected directly to the rear stages of the band-pass filters 114a and 114b respectively, the intensities of the emission lines of atoms and those of ions are measured respectively and converted into electrical signals, and the results of measurement are transferred to a data processing part 117. The data processing part 117 computes and outputs the ratio of the measured light intensities. |
