D-C Breakdown Strength of Air and of Freon in a Uniform Field at High Pressures

D-c breakdown studies of air in a uniform field have been extended to 1,000 kv. D-c studies of Freon (CCl
2
F
2
) have been extended to over 350 kv and to 135 pounds, per square inch absolute. The departure from Paschen's law at the higher values of pressure times gap is noted. The mechanisms which account for the higher insulating strength of such gaseous compounds as CCl
2
F
2
are outlined and their possibilities and limitations in the insulation of high-voltage apparatus are briefly discussed.