| 摘要 |
PURPOSE:To permit simplification and reduction in size of the device and to improve accuracy of the measurement by a method wherein an optical fiber cable is directly inserted into a vacuum container for confining plasma therein and the optical Faraday effect is utilized effectively. CONSTITUTION:A light from a light emitting element 11 is introduced to the inside of a vacuum container 1 by an optical fiber cable 13 after passing through a polarizer 12. When an electrical current flows within the vacuum container 1 due to the plasma current, a magnetic field PHI is produced. This magnetic field acts on a coiled part 13a of the cable, causing an angle of the vibrating plane of light to be changed by theta due to the optical Faraday effect. This angle theta is expressed by thetainfinity KH; where H is the intensity of the magnetic field and K is a constant. From this relation, a value of theta is determined by the plasma position. The affected light is led to an analyzer 14 to take out only the horizontal component of the light, a level of which is detected by a photo detector 15 and then input to an oscilloscope 5. The plasma position can be measured from the attenuated amount of the light. Thus, it becomes possible to permit simplification and reduction in size of the device and to improve accuracy of the measurement. |
