Secondary electron yield measurements from thin surface coatings for NLC electron cloud reduction

In the beam pipe of the positron damping ring of the Next Linear Collider,electrons will be created by beam interaction with the surrounding vacuumchamber wall and give rise to an electron cloud. Several solutions are possiblefor avoiding the electron cloud, without changing the bunch structure or thediameter of the vacuum chamber. Some of the currently available solutions forpreventing this spurious electron load include reducing residual gas ionizationby the beam, minimizing beam photon-induced electron production, and loweringthe secondary electron yield (SEY) of the chamber wall. We will report onrecent SEY measurements performed at SLAC on TiN coatings and TiZrVnon-evaporable getter thin films.