The first step toward operating CEBAF at higher energies has been made possible by the spectacular success of the superconducting RF cavity system in the CEBAF linacs. The higher-than-expected gradients achieved for many of the cavities have immediately opened an opportunity for higher energy running at minimal cost. To operate CEBAF at beam energies of order 6 GeV it will be necessary to upgrade some of the power supplies for the recirculation arc dipoles, and to reprocess some of the lower performance cryomodules so that they approach the performance of the better cryomodules. This evolutionary upgrade will be funded from the ongoing AIP budget of the laboratory.
The second development which led to the ability to upgrade the maximum output energy to the 8-10 GeV range is the fact that the initial 4-recirculation design of the accelerator was changed to a 5-recirculation system during construction as a cost-saving measure. This reduced the number of cryomodules in each linac from 50 to 40. However, the civil construction was already underway at the time of this decision. As a consequence, sufficient ``empty" space remains in each linac tunnel for 25%more linac structure. Filling of this space, together with upgrades in the magnet power supplies and continued improvement in the average cavity performance through reprocessing, will allow CEBAF to reach the plateau of an 8 GeV beam energy. It is expected that further evolutionary upgrades in the performance of the linac structures, achieved through improved understanding of the reprocessing technologies, will allow the beam to eventually reach energies up to about 10 GeV.