A corrugated waveguide based collinear wakefield accelerator is under development at Argonne National Laboratory. The accelerating mode is operating at 180 GHz with a high average power level up to 600 W compounding at the end of the 0.5 m long accelerator module. It is extracted by a dedicated coupler to prevent excessive heating of the corrugated structure of the next accelerator module downstream. Also, it is necessary to monitor beam offsets from the center of the corrugated structure. It is done by utilizing the offset beam’s induced wakefield dipole mode at 190 GHz and extracting it to diagnostic electronics via the second dedicated coupler. Both are contained in the transition section between the accelerator modules*. This paper presents the mechanical design, fabrication, and performance testing of the transition section. Testing included mmWave measurements at ANL and electron beam measurements at Brookhaven National Lab’s Accelerator Test Facility. Both tests involved characterizations of the wakefield modes and coupler’s performances.

A quadruple wiggler consisting of a row of alternating polarity quadrupoles is used in a collinear wakefield accelerator under development at Argonne National Laboratory. We designed such a wiggler and fabricated a prototype consisting of four quadrupoles. The permanent magnet-excited quadrupole has a bore diameter of 3 mm, a length of 25 mm, and a peak magnetic field gradient of 0.94 T/mm. Fine translational and angular adjustment mechanisms were implemented in all quadrupoles to obtain better than one-micrometer alignment of the quadrupole wiggler assembly. The quadrupole wiggler prototype was measured and aligned employing the pulsed wire technique. We describe the design, fabrication, and alignment of this quadrupole wiggler prototype and describe the influence of the ambient temperature on the quadrupole wiggler alignment.