Plasma Light diagnostic for PWFA at SLAC

Summary form only given. A highly relativistic electron beam passes through an oven filled with the particular gas used in the experiment creating a plasma and a large amplitude wake field which causes the beam to lose and gain energy. The energy dumped into the plasma is dissipated through recombination and thermalization. Intensity of the plasma light is proportional to the wakefield amplitude. As the only non-beam diagnostic, study of plasma light can be used to characterize the plasma beam interaction to get the highest acceleration gradient. Moreover the unique spectrum of the gas can be used to as a reliable tool to measure the density vial the theory of Stark Broadening as an alternative to the other plasma density diagnostic tools which may not be available at the higher densities. Application of Plasma Light diagnostic to the past and future plasma experiments will be presented.