[en] Simple techniques were developed to give stable outputs of 337 and 311 μ cw radiation with a conventional HCN laser over several to ten h. By use of a gas mixture of 1:1:2 by volume of CH₄, N₂ and He as the flowing gas, the rate of polymer crust deposition was reduced compared with CH₃CN or CH₄ and N₂ gas. The gas pressure was stabilized to 0.01 torr at 1.6 torr and a flowrate of 6 to 8 torr 1/min. The cathode was not grounded, but negatively charged at 10 percent dc source voltage. Output power stability achieved was +-2 percent without returning, over 10 h periods. (U.S.)

No abstract available

[en] A cryogenic current comparator resistance bridge has been developed to measure the resistance ratios of 1, 10, 100 and 6453.2Ω against 1Ω. The authors show that the precision of the 1-Ω comparison is better than 0.01 ppm. This is attained by using an improved feedback system in the secondary current source