CYCLOTRON RESONANCE PUMPING OF GAS LASERS.
Triannual rept. no. 1, 1 Jun-30 Sep 66,
RADIO CORP OF AMERICA PRINCETON NJ ASTRO ELECTRONICS APPLIED RESEARCH LAB
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A new laser system using combined dcmicrowave-electron-cyclotron excitation was built, capable of high power cw operation. The system uses closed-circuit fluorocarbon coolant flowing through a jacket surrounding the laser tube inside the microwave cavity. Fluorocarbon is used because of its low loss factor at microwave frequencies. Preliminary tests with water cooling and pure dc excitation were carried out on the redesigned laser tube, and cw laser operation at high current levels showed that the erosion problem in the tube had been mostly eliminated. To obtain basic information on the optimum laser parameters, cw and pulse measurements with dc excitation were carried out. It is now possible to differentiate qualitatively between ion drift pump-out effects and other factors affecting laser output as a function of the confining axial magnetic field. The laser tube had a 6 mm diam. and 55 cm length. The results show that due to pump-out, which affects the axial gas density gradient in the tube, magnetic fields up to at least 2.6 kG are beneficial to aid laser operation at the desired low pressures. The larger gas feedback tube reduced the density gradient along the tube to affect the laser output. To transfer rf power to the laser plasma in a magnetic field for more efficient laser operation, MHz rf excitation was examined. By inducing an azimuthal discharge in an 8-mm-diameter tube, discharge power densities in excess of those required for laser operation were obtained. Author
- Lasers and Masers
- Nuclear Physics and Elementary Particle Physics