Vacuum High-Power Microwave Load

A high power load is proposed in TM01 circular waveguide, which utilizes a low Curie Temperature ferrite (garnet material). The specially designed garnet materials would absorb by means of magnetic loss and would be limited to a temperature rise of less than 50 degree C as the magnetic loss would substantially disappear with this temperature rise. Techniques exist for attachment lossy ferrite into waveguide suitable for high vacuum, and are described in: Ultra-High Vacuum RF Load, Final Report Phase I, STTR Grant No. DE-FG02-96ER86049, W. J. Alton and E. P. Chojnacki. Previous activity related to a spinel ferrite which has substantial porosity. Garnet type ferrite materials have a superior microstructure. For this program garnet materials will be manufacturing and subjected to a secondary processing of hot isostatic pressing to achieve 100% density. Surface coating will also be used to maximize electric field capability. To eliminate heating considerations and thereby only test the survivibility in the presence of very high rf electric fields a test section will be fabricated for testing by the sponsor which will consist of a similar garnet composition but one which has essentially no rf magnetic or dielectric loss.