A high energy D O submillimeter laser for plasma diagnostics

A narrow line optically pumped D₂O laser operating at 385 μm has delivered more than 5J in pulses longer than 3 μsec using a large aperture unstable resonator cavity design. Pulse levels >1J, 1 μsec are necessary for a single shot ion temperature measurement by Thomson scattering in large tokamaks. Experiments have, for the most part, been conducted at a 360J, 5 μsec CO₂ laser pump level where high efficiency (～ 2.5 J at 385 μm) has been obtained. These are the highest energies reported to date in the far infrared. In addition, the pulse length has been extended beyond the vibrational relaxation time.