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The UM/L-3 relativistic magnetron operates at -300 kV, 2-5 kA, for durations of 500 ns and is capable of generating microwave pulses of 100's MW output power at 1 GHz for 100's ns. Previous research at UM utilized Metal-Oxide- Junction (MOJ) cathodes to exploit triple point field enhancement to stimulate electron emission. These MOJ cathodes generated fast current turn-on, however, the lifetime of...
From a circuit model for an oscillator, an equation was developed to describe the beam loaded admittance. The equation, which is presented in this paper suggests that the instantaneous beam loaded admittance, may be extracted from the output signal of the oscillator once the cold tube frequency and damping rates have been determined. This technique is used to analyze the behavior of a relativistic...
Experiments have been performed testing magnetic priming at the cathode of a relativistic magnetron to study the effects on high power microwave performance. Three high permeability wires were embedded beneath the emission region of a 1.27 cm diameter cathode, spaced 120 degrees apart (for pi-mode symmetry in an 6 vane magnetron) to perturb both the axial and radial magnetic fields near the emission...
Summary form only given. Recent experiments at the University of Michigan have explored the mechanism of electron emission from triple points (vacuum-conductor-dielectric interface) for application to high current cathodes. Metal-oxide junction (MOJ) cathodes have been developed and tested; these consist of hafnium oxide (HfO2) or magnesium oxide (MgO) coatings over metal (#304 stainless steel) substrates...
We present designs, resistive-load test results and experimental plans of the first 1 MA z-pinch in the USA to be driven by a Linear Transformer Driver (LTD). The Michigan Accelerator for Inductive Z-pinch Experiments, (MAIZE), is based on the LTD developed at the Institute for High Current Electronics in collaboration with Sandia National Labs. This LTD utilizes 80 capacitors and 40 spark gap switches...
Experiments have been performed testing magnetic priming at the cathode of a relativistic magnetron to study the effects on high power microwave performance. Magnetic perturbations were imposed utilizing three, high-permeability nickel-iron wires embedded beneath the emission region of a 1.27 cm diameter cathode, spaced 120 degrees apart (for N/2 symmetry in an N (6) cavity magnetron). These three,...
Experiments have been performed in testing magnetic priming at the cathode of a relativistic magnetron to study the effects on high-power microwave performance. Magnetic priming consists of N/2 azimuthal magnetic perturbations applied to an N-cavity magnetron for rapid generation of the desired number of electron spokes for the pi-mode. Magnetic perturbations were imposed by utilizing three high-permeability...
Magnetic priming experiments on the UM/ L-3-Titan relativistic magnetron (100 MW in L-band, -300 kV, ~3 kGauss), have shown suppression of unwanted modes and major reduction in starting currents for the pi-mode. Data from continuing experiments on magnetic priming at the cathode will be presented, as well as preliminary data on magnetic priming at the cathode and anode. Azimuthally-varying, axial-magnetic-perturbations...
Previous experiments at the University of Michigan have explored the mechanism of electron emission from triple points (vacuum-conductor-dielectric interface) for application to high current cathodes. Recent experiments have fabricated metal-oxide junction (MOJ) cathodes consisting of hafnium oxide (HfO2) coatings over metal (#304 stainless steel) substrates. High dielectric constant HfO2 coatings...
Magnetic priming consists of N/2 azimuthal perturbations applied to the axial magnetic field in an N-cavity magnetron. When employed on the UM/L-3-Titan, 6-cavity, relativistic magnetron (L-band, -300 kV, ~3 kGauss), magnetic priming has shown enhanced performance over uniform-B- field operation. Magnetic perturbations are imposed utilizing Mu-metal wires embedded in either the cathode or both the...
Magnetic priming [1] experiments performed on the UM/Titan relativistic magnetron (6-vane, -300kV, 5-10kA, 0.3-0.5 mus) have shown improvements in magnetron performance over baseline operation. In the current experimental setup, three, 4-cm long magnetic wires (Mu-Metal) are located within the cathode structure, centered beneath the emission region, and spaced 120 degrees apart. These wires produce...
In order to study the effectiveness of this magnetic priming structure, magnetic field data, modeled from the field precision magnum magnetostatics codes, were imported into 3-D MAGIC PIC and run for the relativistic magnetron. Simulations showed faster startup and enhanced pi-mode control compared to the unprimed baseline
Summary form only given. Research is underway to investigate radio frequency (RF) priming of relativistic magnetrons for rapid startup and reduced mode competition. Experiments utilize the MELBA-C to drive the Titan 6-vane relativistic magnetron at parameters: V=-300 kV, I=1-10 kA, e-beam pulselength=0.5 musec, microwave power=100-500 MW, microwave frequency=1-1.3 GHz (with tuning). MELBA-C's ceramic...
Summary form only given. Experiments have been performed on a relativistic magnetron using innovative monolithic metal cathodes (Al). These new types of cathodes are fabricated utilizing KrF laser ablation of metal surfaces to enhance the local E field. Two new types of cathodes invented are: projection ablation lithography (PAL) and ablation line focused (ALF) cathodes. PAL cathodes are fabricated...
Summary form only given. Research is underway to develop a viable technique to implement magnetic priming in the UM/Titan relativistic magnetron (-300 kV, 5-10 kA, 0.3-0.5 mus) for rapid startup and mode control. Magnetic priming involves imposing N/2 azimuthal variations in the axial magnetic field of an N-vane magnetron operating in the pi-mode. This type of magnetic priming has been demonstrated...
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