Laser light absorption measurements in an interaction-produced plasma column

Abstract
100 J of 10.6‐μ laser energy produced in a 1.5‐μs pulse was focused to a 2‐mm‐diam spot by a 50‐cm‐focal‐length mirror. A plasma was created by breakdown in the 70‐ns gain‐switched peak of the pulse where the light flux becomes greater than 1010 W/cm2. The plasma column subsequently created in 5–20 Torr of hydrogen by the absorbed light energy was observed by 5‐ns exposure and streak photographs. The aspect of beam trapping is demonstrated by measurements of the transmitted light intensity radial distribution and significant energy absorption is shown by the measurement of transmitted energy.