Theoretical and Experimental Investigation of Electron Beam Acceleration and Sub-Millimeter Wave Generation

Abstract

111mated to average i h~our Pet rewonn e. snociidng 1the time lot reviewing instructionst searchtng i stiflq cats sources ; ',II; ill In r w., the (ollenof of information send comments regarding th,• ,rdf• l estimate or a•y othera awec of It s Approved for public release; distribution unlimited. ABSTRACT (Maximum 200 words)The overall objective of our research for ARO is to develop devices that have the potential for being compact generators of submillimeter-wave radiation.(1) The high-harmonic gyro-frequency multiplier, which is an efficient generator of high frequency rf, will be tested at the tenth-harmonic in our rebuilt test-stand. (2) High-power harmonic gyro-TWTs can be designed to operate in high order modes in large size waveguide by using the marginal stability design criterion. (3) Our high power, second-harmonic TE 2 1 gyro-TWT, which is predicted to generate an order of magnitude higher power than state-of-the-art fundamental frequency gyrotrons, has been fullv designed and construction is well underway.(4) The interaction strength in our high-harmonic CARM increases as the electron Larmor radius moves closer to the wall radius as the magnetic field is lowered towards a grazing intersection.(5) A high performance amplifier is predicted to result from our initial gryo-klystron experiment A major objective of our research under the ARO contract is to investigate novel approaches which will lead to practical, high frequency (> 100 GHz) sources. For cost effecAJdia[lity Cod tiveness, we have carried out a significant portion of the work at lower frequencies where we Avai vtaor can economically assemble the basic experiments necessary to carry out proof-of-principle physics studies. One must demonstrate ingenuity and cleverness to make dramatic advances \y\ with our moderate level of funding. However, as discussed in detail in Secs. III and IV, all of the devices under study have the potential for high frequency operation.During the last year of the contract, four important papers describing our ARO-funded contributions to millimeter-wave and sub-millimeter wave source development were pub- 20, 393 (1992)), describes the performance and capability of a frequency selective reflector that is sure to play an important role in future high power overmoded oscillators.