Electron density measurements during microwave generation in a high power backward-wave oscillator

Hegeler, F.; Grabowski, C.; Schamiloglu, E.

doi:10.1109/27.700754

Cited by 40 publications

(26 citation statements)

References 9 publications

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“…By using density test functions to compute the maximum self-field parameters for annular beams, we compare theoretical parameter limits with those corresponding to three annular beam experiments -1.3 GHz RKA experiment at LANL [1], 1.3 GHz RKO [2] experiment at AFRL, and the 9.4 GHz BWO [3] experiment at the University of New…”

Section: Introductionmentioning

confidence: 99%

“…However, the increase in beam-wall interaction, especially when the beam becomes strongly bunched during highpower operation of such a device, may require a stronger magnetic field for beam focusing. Indeed, many HPM devices driven by annular beams suffer from considerable beam losses and the well-known problem of rf pulse shortening [1,3].…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, a number of high-power microwave (HPM) experiments have employed high-intensity bunched annular relativistic electron beams, such as the relativistic klystron amplifier (RKA) experiment at Los Alamos National Laboratory (LANL) [1], relativistic klystron oscillator (RKO) experiment at Air Force Research Laboratory (AFRL) [2], and the backward wave oscillator (BWO) at the University of New Mexico [3]. Since an annular beam typically has a transverse size, which is of the order of the conductor wall radius, the beam-wall interaction can be increased compared to the interaction of a pencil beam with a wall.…”

Section: Introductionmentioning

confidence: 99%

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Equilibrium and confinement of bunched annular beams

Hess

Chen

2002

Physics of Plasmas

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The azimuthally invariant cold-fluid equilibrium is obtained for a periodic, strongly bunched charged annular beam with an arbitrary radial density profile inside of a perfectly conducting cylinder and an externally applied uniform magnetic field. The selfelectric and self-magnetic fields, which are utilized in the equilibrium solution, are computed self-consistently using an electrostatic Green's function technique and a Lorentz transformation to the longitudinal rest frame of the beam. An upper bound on the maximum value of an effective self-field parameter for the existence of a bunched annular beam equilibrium is obtained. As an application of the bunched annular beam equilibrium theory, it is shown that the Los Alamos National Laboratory relativistic klystron amplifier experiment is operating slightly above the effective s elf-field parameter limit, and a discussion of why this may be the cause for their observed beam loss and microwave pulse shortening is presented. The existence of bunched annular beam equilibria is also demonstrated for two other high-power microwave (HPM) experiments, the relativistic klystron oscillator experiment at Air Force Research Laboratory and the backward wave oscillator experiment at the University of New Mexico. In general, the results of the equilibrium analysis will be useful in the determination of the stability properties of strongly bunched annular beams in HPM devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Equilibrium and confinement of bunched annular beams

Hess

Chen

2002

Physics of Plasmas

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“…Several mechanisms of RF pulse shortening have been proposed [3], ranging from plasma formation at various locations in the device to nonlinear effects at the RF output section [4][5][6][7]. However, few of them have been fully verified in terms of theory, simulation and experiment.…”

Section: Introductionmentioning

confidence: 99%

Electron beam halo formation in high-power periodic permanent magnet focusing klystron amplifiers

Pakter

Chen

2000

IEEE Trans. Plasma Sci.

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Electron beam halo formation is studied as a potential mechanism for electron beam losses in highpower periodic permanent magnet focusing klystron amplifiers. In particular, a two-dimensional selfconsistent electrostatic model is used to analyze equilibrium beam transport in a periodic magnetic focusing field in the absence of radio-frequency signal, and the behavior of a high-intensity electron beam under a current-oscillation-induced mismatch between the beam and the periodic magnetic focusing field. Detailed simulation results are presented for choices of system parameters corresponding to the 50 MW, 11.4 GHz periodic permanent magnet (PPM) focusing klystron experiment performed at the Stanford Linear Accelerator Center (SLAC). It is found from the self-consistent simulations that sizable halos appear after the beam envelope undergoes several oscillations, and that the residual magnetic field at the cathode plays an important role in delaying the halo formation process.

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“…Recently, beam losses have been measured in a number of high-intensity accelerator and high-power microwave experiments. For example, beam power losses have been observed in several periodic permanent magnet (PPM) focusing klystrons [7] at the Stanford Linear Accelerator Center and in other HPM sources elsewhere [8]. Beam loss has also been attributed to be a limiting factor in the proton storage ring (PSR) [9] at Los Alamos and in the relativistic heavy ion collider (RHIC) [10] at Brookhaven.…”

mentioning

confidence: 99%