Convertor for Economic Power Generation from Adjustable Speed Wind Mills

65706 Negative-electron-affinity (NEA) photocathodes, which produce polarized electrons, are a vital component of electron accelerators. For the next Linear Collider (NLC), the polarized electron beam intensity must be at least 20 times greater than that produced by strained GaAs, used in the current generation of photocathodes. Additionally, the degree of electron polarization needs to be increased beyond the 75% currently attainable, and intrinsic materials properties must be tailored to improving the surface charge limit. This project will develop a new generation of photocathodes capable of yielding intense, highly polarized electron beams for use in advanced electron colliders. A strained-superlattice, formed from altering layers of GaAs and GaAsP approximately ten monolayers thick, will be utilized. In Phase I project the GaAs/GaAsP superlattice structure will be grown by molecular beam epitaxy (MBE). This technique is capable of atomic layer precision and is superior to metal organic chemical vapor deposition in use for growing strained GaAs. The optimization of the superlattice will be performed by varying the structural design and the growth conditions in a matrix of experiments. Commercial Applications And Other Benefits as described by awardee: A highly efficient polarized electron source should find use in experimental research at the Stanford Linear Accelerator Center and other electron collider facilities. These devices would also have applications in magnetic research and surface science