Experimental Results and Technical Results and Development at CTFII

The second phase of the Compact Linear Collider Test Facility (CTF II) has demonstrated the feasibility of two key ingredients of the Compact Linear Collider scheme (CLIC) [1], namely the acceleration with a 30 GHz normal conducting linac and the 30 GHz RF power production by a tightly-bunched, high-charge drive beam running parallel to the main beam. This beam is produced and accelerated with a 3 GHz linac using an RF-photo-injector and two travelling-wave sections, all specially developed for handling very high charges. A magnetic chicane compresses the micro-bunches to their nominal length. A mm-wave spectrometer, coupled to the beam pipe, allows non-destructive measurements of bunch length. So far a total acceleration of 60 MeV has been obtained using a string of five accelerating structures with a total active length of 1.4 m. The corresponding drive-beam deceleration is 6 MeV. The flexibility and extensive beam instrumentation allows a variety of other experiments, such as measurements of emittance growth and energy loss in bunch compressors due to coherent synchrotron radiation, high-gradient tests in single-cell 30 GHz cavities, high-power tests of a planar 30 GHz RF structure and tests of beam position monitor prototypes.