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various optical echoes. He demonstrated the two-photon echo and, in 1977, was a codiscoverer of the tri-level echo. In 1978 he joined the staff of Avco Everett Research Laboratory, Everett, MA. Since then he has been involved in a variety of projects related t o his background in nonlinear optics and atomic spectroscopy. Hemade major contributions to the Avco-Exxon uranium isotope separation program and developed a practical technique of photographing far-IR laser intensity distributions. He developed the theory of a thermoacoustic instability which occurs in the gas of a pulsed COz laser. He is currently working on various aspects of stimulated Raman scattering, especially wavefront preservation. He has published over 30 journal papers in nonlinear optics and atomic spectroscopy. Dr. Flusberg is a member of the American Physical Society and the Optical Society of America.

We report on the design and commissioning of a real time harmonic global orbit feedback system for the NSLS X-ray ring. This system uses 3 pickup electrode position monitors and 16 trim dipole magnets to eliminate 3 harmonic components of the orbit fluctuations. Because of the larger number of position monitors and trim magnets, the X-ray ring feedback system differs from the previously reported VUV ring system in that the Fourier analysis and harmonic generation networks are comprised of MDAC boards controlled by computer. The implementation of the global feedback system has resulted in a dramatic improvement of orbit stability, by more than a factor of five everywhere. Simultaneous operation of the global and several local bump feedback systems has been achieved.