Study of multipactor in X-band dielectric-loaded accelerating structures

Summary form only given. A joint program is under way at the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL) to develop and test dielectric-loaded structures for use in high-gradient RF linear accelerators. DLA structures offer the potential of a simple, inexpensive alternative to conventional copper disk-loaded structures for use in high-gradient linear accelerators. The study makes use of structures developed and fabricated by ANL, and carries out its testing program on the X-band magnicon facility at NRL at drive powers up to 10 MW. We have carried out tests of DLA structures employing cylindrical dielectric liners fabricated from both high purity alumina (epsi~9.4) and magnesium calcium titanate (epsi~20). In the case of alumina, we have tested structures either with or without a low-secondary-coefficient TiN coating. In all cases, a strong multipactor effect has been observed. However, the effect has been found to depend on the both the dielectric used and the experimental geometry. Further tests are planned, including tests using other dielectric materials. The latest results will be presented and discussed