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Recently, considerable attention has been given to the development of relativistic high-power microwave sources with the capability of broad-band frequency tuning. We have demonstrated frequency tunability via computer simulations and experiments in an X-band backward wave oscillator (BWO) with a modified cavity reflector.
In the present work we suggest to use cyclotron absorption to suppress a wave that is responsible for feedback in traveling wave tubes (TWTs) without removing reflections and other causes of parasitic self-excitation that can lead to controlled gain by varying the magnitude of the guide magnetic field inside the stationary region of cyclotron absorption (RCA). We illustrate amplification in the RCA...
Summary form only given. We analyze conditions under which a double-humped potential function of electron beam states is formed in a system of coordinates that is moving with the electrons. We show that periodic states with large amplitudes can exist. Such states can be used as the basis for microwave oscillators with a strong Doppler frequency shift. In addition, we predict the existence of solitary...
Summary form only given. The stability of stationary states of dense electron beams propagating in weakly irregular channels, in particular, in channels with non-deep periodically corrugated walls, is investigated using the method of coupled waves. We show that Bursian's instability can develop, leading to the formation of virtual cathodes or their disruption. In unlimited channels, separate zones...
Summary form only given. Smith-Purcell (SP) radiation is produced when an electron beam passes over a metallic periodic structure and a continuous spectrum of modes associated with the beam is scattered by the grating. Most of the scattered modes are evanescent, while some may propagate. The SP radiation wavelength is found to be proportional to the grating period, L, and inversely proportional to...
Summary form only given. One of the important problems for high power microwave sources is to provide removal of spent electrons to avoid overheating and erosion of the output channel, part of which is used as the electron dump. An effective solution of this problem is achieved by spreading the electrons along the surface of the output channel. However, it is noted that changing the location of the...
Over the past 30 years, the paraxial diode has utilized a gas-filled transport cell to focus an electron beam onto a high-Z target in order to generate intense x-rays for flash radiography. One of the key objectives is to create a small radiographic spot, which in turn is related to the focusing dynamics of the beam. For gas-filled transport cells, the primary limitation to achieving a small time-integrated...
Summary form only given. Spectroscopic experiments are being conducted on a plasma-filled paraxial X-ray radiography diode on the RITS-3 accelerator at Sandia National Laboratories. Initial data shows line and continuum emission occurring during the time of the electron beam propagation through a partially-ionized background plasma. Additional impurity ion species have also been identified. The purpose...
Summary form only given. In flash X-ray radiography, one of the key goals is to focus an electron beam onto a high-Z-target to generate X-rays. One of several goals is to create a small radiographic spot. The paraxial diode, which utilizes a gas-filled transport cell to focus the beam into a small spot, has been investigated for several decades. It has been shown in simulations using LSP, a particle-in-cell...
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