Bunch Compressor Performances at the CLIC Test Facility

The Test Facility of the "Compact Linear Collider" (CLIC) at CERN (CTF), has to prove the feasibility of transporting high charge beams through decelerating structures at 30 GHz to create RF power. This RF power is used to supply, in the final scheme, the cavities of the main linac. To optimise this power generation, a bunch compressor has been installed in the test line. This compressor shortens the electron bunches after creation and acceleration in the RF gun. The compressed bunches are then accelerated by a high gradient cavity (50 MV/m) and transported to a 30 GHz cavity. Compressed bunch length mesurements showed that lengths of 0.6 mm (rms) were obtained at the entrance of 30 GHz cavity for a 10 nC beam. Compression of electron bunches of charges between 2 and 17 nC have also been measured. Emittance measurements were done to study the transverse effects of the bunch compressor on the beam. The use of the code PARMELA allowed the design and optimisation of the chicane. The simulations results have been compared to the experimental measurements.