An electronically controlled beam focusing/ defocusing Phased Array Antenna (PAA) system is proposed for use in Microwave Imaging Reflectometry (MIR) systems, which are being developed to measure ...plasma density fluctuations. The design, construction and performance of a Ka-band 1times8 true time delay E-plane beam scanning and broadening phased array system based on piezoelectric transducer controlled delay line technology using antipodal elliptically-tapered slot antennas are presented. The beam is steered from -21degto +24degand the 3 dB beamwidth is widened by about 10deg, the latter being the requirement for the target MIR system.
The University of California at Davis (UCD) 34 GHz peniotron has undergone initial RF testing. The peniotron is a second-harmonic device incorporating a fundamental mode 4-vane slotted ...(magnetron-type) interaction circuit and a novel cusp electron gun. Initial results indicate that the device is operating in the intended mode but at reduced beam voltage and hence, with reduced output power. The device incorporates output coupling directly to each of the four circuit slots and to date, a maximum of 25 kW (peak) output power has been measured utilizing only one of the ports.
Millimeter wave solid state array technology has broad applicability in areas ranging from radar and nondestructive testing to cancer hypertherapy and plasma diagnostics and is actively under ...investigation at UC Davis. Phased antenna arrays utilizing Schottky varactor loaded transmission lines as the phase controlling elements have been designed, simulated, fabricated and are being tested. Broadband quasi-optical overmoded waveguide frequency multiplier grid array systems have been designed, simulated, fabricated and are under test with a goal of providing Watt level output powers from 50-200 GHz. Micro-electromechanical systems (MEMS) based switch and capacitor arrays have been designed and fabricated on silicon wafers with traditional IC processing techniques, resulting in devices with physical dimensions on the order of a few tens of microns.
Dielectric-loaded wideband gyro-TWT LEOU, K. C; MCDERMOTT, D. B; LUHMANN, N. C
IEEE transactions on plasma science,
1992, Letnik:
20, Številka:
3
Journal Article
Second-Harmonic Axis-Encircling Electron Beam Gyro-TWT Amplifier Harriet, S.B.; McDermott, D.B.; Luhmann, N.C.
2006 IEEE International Vacuum Electronics Conference held Jointly with 2006 IEEE International Vacuum Electron Sources,
2006
Conference Proceeding
A Ka-band TE 21 second-harmonic gyro-TWT amplifier with a large-orbit axis-encircling beam from a Northrop Grumman Cusp gun is being fabricated and tested at UCD. The device is predicted to produce ...50 kW with 20% efficiency, 30 dB saturated gain and 3% bandwidth
Improving the electron beam power and quality is essential to increasing the power and performance of the gyro-TWT. We have designed, and tested, a new magnetron injection gun (MIG) with nominal ...alpha=1.5 and calculated axial velocity spread (via EGUN) of 3.9% (neglecting cathode surface roughness, emission non-uniformity, and other defects). The gun is designed to nominally operate at 100 kV with ~8 Amp beam current at a cathode current density of 30 A/cm 2 and uses Scandate impregnated cathodes. Beam analyzer tests show that the gun performs with excellent beam quality and that the design is flexible with respect to maintaining the beam quality with variable operating parameters such as voltage, current, and compression. This is a low compression (only 12) thin beam design. The surface quality of advanced high current density cathodes can be inferred from the beam quality measurements. Advanced gyro-TWT design using the improved MIG is discussed.
A 30 GHz second-harmonic TE/sub 21/ gyro-TWT amplifier is being constructed at UCD that will be driven by a 70 kV, 3.5 A, v/sub ⊥//v/sub Z/=1.2, Δv/sub Z//v/sub Z/=7%, axis-encircling electron beam ...from a Northrop Grumman cusp gun. The single-stage amplifier is predicted by a large-signal simulation code to generate 50 kW at 30 GHz with 20% efficiency, 32 dB saturated gain and 3% constant-drive bandwidth.
Highly efficient 34 GHz peniotron Dressman, L.J.; McDermott, D.B.; Hirata, Y. ...
Twenty Seventh International Conference on Infrared and Millimeter Waves,
2002
Conference Proceeding
While high conversion efficiency has been demonstrated in peniotrons, practical application of the device requires that power be efficiently extracted from the cavity. The UCD peniotron is designed ...to achieve high overall device efficiency and power output (130 kW peak) by employing an over-coupled cavity driven by a Northrop Grumman Cusp gun. Stability is insured through the use of a fundamental-mode interaction with the second cyclotron harmonic of the axis-encircling electron beam.
Summary form only given. Two high performance gyro-TWT amplifiers are being constructed at UCD. A third-harmonic gyro-TWT amplifier operating in the TE/sub 41/ mode will extend the proven concept ...that the electron beam current can be significantly higher in a stable harmonic gyro-TWT amplifier than at the fundamental due to the comparatively weaker harmonic interaction. Our previous second-harmonic gyro-TWT stably generated a record breaking output power of 210 kW. For stability, the circuits are sliced to suppress electromagnetic modes without the desired symmetry and the 100 kV, 100 A v/sub /spl perp///v/sub z/=1.35 electron beam from a magnetron injection gun is placed at the null of the strongest remaining gyro-BWO mode. The single-stage gyro-TWT is predicted to produce 2 MW with 20% efficiency, 30 dB saturated gain and 5% bandwidth.
2-D fluctuation imaging diagnostic for TEXTOR Domier, C.W.; Deng, B.H.; Wang, J. ...
Twenty Seventh International Conference on Infrared and Millimeter Waves,
2002
Conference Proceeding
A system capable of simultaneous 2-D imaging of electron density and temperature turbulence on TEXTOR is presently under development. Concept design details are presented. The system combines both ...electron temperature and density diagnostic techniques into a single instrument capable of the simultaneous measurement of both fluctuations (both turbulent and coherent) on the TEXTOR tokamak.
