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U.S. Department of Energy
Office of Scientific and Technical Information

Cavity-mirror degradation in the deep-UV FEL

Conference ·
OSTI ID:238663
; ;  [1]
  1. Electrotechnical Lab., Ibaraki (Japan); and others
It is known that the degradation of dielectric multilayer mirrors used in short wavelength free-electron lasers (FELs) is caused by the carbon contamination on the mirror surface and the defects inside the dielectrics. We reported last year that the degraded dielectric multilayer mirrors can be repaired with both surface treatment by RF-induced oxygen plasma and thermal annealing. However, such a mirror degradation is still one of the most critical issues in the deep ultraviolet (UV) FELs, because the fundamental undulator radiation resonating in the laser cavity, the intensity of which is much higher than that of higher harmonics, can be sufficiently energetic to cause the mirror degradation through photochemical reactions. We are investigating the mirror degradation mainly in the deep UV region down to 240 nm. The experimental results will be shown. The mirror degradation mechanism will be discussed.
Research Organization:
Brookhaven National Lab., Upton, NY (United States)
OSTI ID:
238663
Report Number(s):
BNL--61982-Absts.; CONF-9508156--Absts.; ON: DE96002729
Country of Publication:
United States
Language:
English