The RFQ-DTL matching section of the SSCL Linear Accelerator matches the 2.5 MeV H- beam from the RFQ into the acceptance of the 70 Mev Drift Tube Linac (DTL). To provide longitudinal phase space tuning, two RF buncher cavities with a resonant frequency of 427.617 MHz and with a maximum E0TL of 160 kV are required. To meet the limited space requirements, it was decided to use double gap buncher cavities

The RFQ-DTL matching section has four variable field quadrupole magnets in a FODO lattice to match the 2.5-MeV, 27-mA, H/sup -/ beam from the RFQ to the acceptance space of the DTL, as well as to provide beam steering. In addition, there are two rf buncher cavities to provide longitudinal phase space tuning. An ensemble of beam diagnostics including input and output beam current toroids and beam position monitors, a wire scanner for beam profile measurements, a slit and collector device for beam emittance measurements, and a Faraday cup is used to quantify the matching section performance. The finalized design of the major components of the RFQ-DTL matching section is presented as well as the status of its construction.< >

SSCL has completed the preliminary design of the RFQ to DTL matching section for the SSe. The matching section matches a 2.5 MeV H- beam to the acceptance of the DTL. The design is comprised of two double-gapped bunching RF cavities, four variable field permanent magnet quadrupoles (VFPMQ), two primary diagnostic chambers, and a vacuum beam line which integrates other diagnostic instruments such as beam position monitors and beam current toroids. The entire design is integrated in a limited longitudinal space of 54 cm. The double-gapped cavities operate at 428 MHz at a power of 25 kW. Their compact size permits integration into a standard-sized chamber. Four VFPMQ's, developed by Los Alamos National Lab, are used as the beam focusing and steering elements. The magnets achieve a maximum GXL product of 4.0 Tesla. Gradient variability is achieved through a rotating outer magnet ring. Linear actuation of each magnet in its focus degree of freedom permits beam steering. The two diagnostic chambers can accommodate up to eight actuated instruments. One chamber is located after the second quadrupole magnet; the second is located after the fourth quadrupole magnet. The vacuum beam line is achieved using bellows, beam tubes, and various seals. Ion pumps located on the RF cavity chambers achieve the required 3.3E-7 Torr vacuum.