UV HIGH REFLECTOR TECHNOLOGY FOR FREE ELECTRON LASERS

A NEW PROGRAM AT NIST AIMS TO DEVELOP A FREE ELECTRON LASER (FEL) USER FACILITY TUNABLE WELL INTO THE ULTRAVIOLET. THE SHORT WAVELENGTH LIMIT OF OPERATION IS MAINLY DEPENDENT ON THE OPTICS PERFORMANCE. THE BEST KNOWN OPTICAL MATERIALSARE DEGRADED BY THE HARMONIC RADIATION PRODUCED UNAVOIDABLY DURING FEL OPERATION. THE DEVELOPMENT OF IMPROVED MATERIALSFOR THIS APPLICATION REQUIRES THE MEASUREMENT (AND MINIMIZATION) NOT JUST OF THE STATIC LOSSES, BUT OF THE SUM OF THE STATIC AND THE ABOVE DYNAMIC LOSSES. WE PROPOSE TO MIMIC THE FEL HARMONIC EFFECTS WITH A PHOTON BEAM AT A SYNCHROTRON RADIATION FACILITY, AND MEASURE THE COMBINED STATIC AND DYNAMIC LOSSES OF A RANGE OF CANDIDATE MATERIALS IN THE ULTRAVIOLET WAVELENGTH RANGE OF THE NIST FEL. WE WILL UTILIZE A STATE-OF-THE-ART VACUUM TEST CHAMBER AND RINGDOWN MEASUREMENT TECHNOLOGY DEVELOPED AT DEACON RESEARCH, WHICH NEEDS ONLY MINOR MODIFICATION TO OPERATE IN THE UV. IN PHASE I, WE WILL ANALYZE THE REQUIRED EQUIPMENT MODIFICATIONS, TEST ONE OF THE APPROACHES, AND ACQUIRE AN OPTIMUM SET OF TEST SAMPLES. THE PHASE II PROGRAM WILL INSTALL THESE CHANGES INTO THE CHAMBER AND MEASURE THE COMBINED STATIC-DYNAMIC LOSSES ACROSS THE EXPECTED NIST OPERATING RANGE. THIS INFORMATION WILL THEN BE FOLDED INTO A PROGRAM TO OPTIMIZE THE OPTICS TECHNOLOGY.