| 摘要 |
PURPOSE:To decrease the noises of laser output light without decreasing the power of the laser output light, by keeping the surface temperature of a cathode constant with respect to time. CONSTITUTION:A DC voltage is applied to the cathode 26 from a DC power source 38. Based on the application of said DC voltage, the temperature of the cathode is kept at the optimum temperature for discharging electrons, e.g. 1,200 deg.K. By applying the DC voltage to the cathode 26 in this way, the surface temperature of the cathode 26 is not instantaneously changed, but it is kept constant. The amount of the discharged electrons depends on the surface temperature of the cathode. Therefore, when the temperature is constant for infinitesimal time, the amount of the discharged electrons is also kept constant, and the stabilization of the discharge can be achieved. |
