High-energy D2O submillimeter laser for plasma diagnostics

A narrow line optically pumped D2O laser operating at 385 μm has delivered more than 5 J in pulses longer than 3 μsec using a large aperture unstable resonator cavity design. Pulse levels which are > 1 J and 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 360 J, 5 μsec CO2 laser pump level where high efficiency (approx. 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