Side on interferometry at 10.6 μm of Theta pinch plasmas

An experiment for measuring electron density spatially resolved with high time resolution is described. The experiment was performed side on on a Theta pinch plasma. The light source (TEA-CO₂ laser), the window problem, the area detector for the interferogram are discussed. The sensitivity of the technique is 1–2×10¹⁵ electrons/cm². Some examples of measured density profiles show that the method may be used effectively on toroidal plasma machines.