CLIC , A 0 . 5 TO 5 TeV

The CLIC study of a hig h energy (0.5 5 TeV), high luminosity (10 10 cm sec) e± linear collider is presented . Beam acceleration using high frequency (30 GHz) normal-conductin g structures operating at high accelerating fields (100 to 200 MV/m) significantly reduces the length and, in consequence, the cost of the linac. Based on new beam and linac parameters derived from a recently developed set of general scalin g laws for linear colliders, the beam stability is shown to be similar to lower frequency designs in spite of the strong wakefield dependency on frequency. A new cost-effective and efficient drive beam generation scheme fo r RF power production by the so-called "Two Bea m Acceleration (TBA)" method is described. It uses a thermioni c gun and a fully-loaded normal-conducting linac operatin g at low frequency (937 MHz) to generat e and accelerat e the drive beam bunches, and RF multiplication by funnelling in compressor rings to produce the desired bunc h structure. Recent 30 GHz hardware developments and result s from the CLIC Test Facility (CTF), assessing the feasibility of the scheme, are described.