Download or read book Experimental Study of a 1.5-MW, 110-GHz Gyrotron Oscillator written by James Paul Anderson and published by . This book was released on 2005 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) a rotating probe indicates that the work function variation around the azimuth, the global spread, is 0.03 eV for the first cathode, 0.02 eV for the second. The spread due to local (microscopic scale) work function variations is then calculated to be around 0.03 eV for both cathodes. Based on the beam azimuthal measurements, temperature variation is ruled out as the cause of emission nonuniformity. In another part of the current probe experiment, current-voltage curves were measured at azimuthal locations in 30° increments for several cathode temperatures. From this extensive set of data the work function distribution parameters were identified over small sections of the cathode for the entire cathode surface. In addition, a formulation is presented of the irradiance moments applied to the determination of phase profiles of microwave beams from known amplitudes. While traditional approaches to this problem employ an iterative error-reduction algorithm, the irradiance moment technique calculates a two-dimensional polynomial phasefront based on the moments of intensity measurements. This novel formulation has the important advantage of identifying measurement error, thus allowing for its possible removal. The validity of the irradiance moment approach is shown by examining a simple case of an ideal Gaussian beam with and without measurement errors. The effectiveness of this approach is further demonstrated by applying intensity measurements from cold-test gyrotron data to produce a phasefront solution calculated via the irradiance moment technique. The accuracy of these results is shown to be comparable with that obtained from the iteration method. This algorithm was then applied to the design of the phase correcting mirrors used in the internal mode converter experiment.