During the past year, CEBAF at Jefferson Lab has demonstrated its full capacity of sustained 800 kW beam power. All systems performed as intended. The energy stability at the design parameters of 4.0 GeV, 200 muA CW beam was measured to be better than 3x10{sup -5} rms. During the fall of 1997, physics experiments were conducted using 4.4 GeV beam. Having demonstrated the benefits of in situ helium/rf processing of SRF cavities for increasing the energy reach of CEBAF, we began a program of processing all installed cryomodules. This processing has proven effective against the principal gradiation limitation of the SRF cavities in CEBAF: discharges at the cold rf waveguide window, induced by electron field emission in the cavities. Such effects limit approximately half of the cavities. Regular operation at 5.0 GeV is just beginning, and preparations are underway to support 5.5 GeV in early 1999.
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