Proposed multipass Thomson scattering system for tokamaks

A multipass laser system is proposed for extending the period over which Thomson scattering measurements can be made with tokamaks. A Pockels cell and polarizer are used to reroute the pulse, which is reflected back through the plasma, away from the main amplifier, and onto a mirror, thus forming a closed system. A number of lenses and apertures are included in the system to maintain beam quality, with low gain amplifiers being used to maintain pulse energy.