The split-cavity oscillator: a high-power E-beam modulator and microwave source

Marder, B.M.; Clark, M.C.; Bacon, L.D.; Hoffman, James M.; Lemke, R.W.; Coleman, P. D.

doi:10.1109/27.142833

Cited by 83 publications

(41 citation statements)

References 15 publications

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“…This efficiency is achieved in circular cavities operating in the TM olO mode for which the axial electric-field distribution is uniform along the interaction space. On the other hand , a cavity bisected by a diaphragm or a conducting foil [5][6][7] so as to support a nmode standing wave in the partitioned cavity yields a two-fold increase in the conversion efficiency, thus providing a 40% efficiency level [7][8]. These previous results were obtained through optimization schemes on the basis of particle-in cell (PIC) simulations without much emphasis on the physical mechanisms underpinning the efficiency enhancement process.…”

Section: Efficiency and Electron Trajectorymentioning

confidence: 94%

“…7 that electron #22 gets reflected after crossing the transition. Such an effect is explained by inequality (6). After transiting the region of g>O, electron #22 arrives at the transition with vo=0.065 and ¢b=0.5 17t to start its journey through the region where g= -0.067.…”

Section: Z( T)=g(cos T -Cos¢o)+(t -¢O)(vo +Gsin¢o)mentioning

confidence: 94%

“…The inset shows the distribution of initial phases of the beam electrons, for which the initial changeof momentum is proportional to -cos r/Jo (6). …”

mentioning

confidence: 99%

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Conversion efficiency in axial monotrons

Barroso

2009

2009 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)

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Abstract~A comparative st udy is given on the bunching mechanisms which develops in transit-time tubes with RF-field bunching, often referred to as monotrons. Uniform and stepped wise longitudinal electric-field profiles are discussed, and it is shown that the two-fold enhancement in the conversion efficiency of a monotron operating in the 7t mode--instead of the longitudinally uniform TM olO mode for which the efficiency is limited to 20 percent-arises from a phase synchronization process due to the action of RF electric fields of reversed signs in each partition of the bisected cavity dp =qEof(z)cos(OJt+¢o) dt in which the electron position is given by equation(1) the trajectory (2) In the calculation which follows , we normalize the motion variables according to p= p / me , == zOJ/ c, t = OJ t whereby the force equation becomes nondimensionalized, 0.0 0.5 1.0 1.5 2.0 2.5 3.0 normalized axial distance zw/c Fig. 1. Stepped field profile repres ented by the function f ei) = -tanh[l 00(= -d/2) with d = 2.90 . OJ -0 E 0 rn .!!! <+= o 0.. -1 where p is the electron momentum, q= -I e I and m are the electronic charge and the electron rest mass, OJ is the angular frequency of the RF field of amplitude Eo, and ¢o denotes the electron entrance phase. In the force equation j{z) specifies the electric-field axial distribution. For the TM olO mode the field is uniform,j{z) = 1, and to describe the axial distribution of the 1t mode we use the analytical function profile fez) = -tanh[100(z-d / 2)] as illustrated in Fig. 1. (4) (3) [511+Wo(keV)]2 -511 2 p(O) = 511 .dP-= = -g f(z)cos(t + ¢o) dt where g = qEo / tome. First, using f (z)=l and g =0.045 (to be justified later), the force and trajectories equations are numerically solved subject to the initial conditions =(¢o) =0, p(¢o) =Po with the initial momentum Po corresponding to the injection energy W o =1O keY, through

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Section: Efficiency and Electron Trajectorymentioning

confidence: 94%

Section: Z( T)=g(cos T -Cos¢o)+(t -¢O)(vo +Gsin¢o)mentioning

confidence: 94%

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Conversion efficiency in axial monotrons

Barroso

2009

2009 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC)

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“…As is known, TTO as one of the most potential HPM sources has the virtue of simplicity in structure, stability in output power, and monochrome in output frequency (Marder et al, 1992;Barroso et al, 2000;2002). Due to these valuable merits, we plan to design a compact Ku-band relativistic TTO with low guiding magnetic field for generating more than 500 MW Ku-band HPM.…”

Section: Overview Of the Devicementioning

confidence: 96%

A Ku-band coaxial relativistic transit-time oscillator with low guiding magnetic field

Ling

Zhang

et al. 2014

Laser Part. Beams

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A novel coaxial relativistic transit-time oscillator with low guiding magnetic field is proposed and investigated to generate high power microwave at Ku-band. With the coaxial structure and a quasi body wave adopted as the operating mode, the device has a larger space-charge limiting current, higher power handling capacity, and lower guiding magnetic field. Moreover, for further improving the output power, a coaxial TM 02 mode resonant reflector is well designed. Main structure parameters of the device are optimized by particle in cell simulations. A typical simulation result is that, with a 358 keV, 7.25 kA beam guided by a magnetic field of about 0.7 T, an 810 MW microwave pulse at 14.25 GHz is generated, yielding a conversion efficiency of about 31%. The primary experiments are also carried out. At a low guiding magnetic field of 0.7 T, a microwave pulse with power of 400 MW, pulse duration of 30 ns, frequency of 14.3 GHz close to the simulation one, and efficiency of 15.4% is generated.

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“…The Split-Cavity Oscillator (SCO), which utilizes transit-time bunching of the beam to generate microwave energy, has been investigated by Marder, Clark and coworkers (Marder et al 1992). Power output is moderate; Pulses in the range of 100 MW for durations on the order of 100 ns have been achieved.…”

Section: Split-cavity Oscillatorsmentioning

confidence: 99%

A Brief Technology Survey of High-Power Microwave Sources

Bacon

Rinehart²

2001

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This report provides a brief summary of the characteristics of contemporary high-power microwave sources. The focus is on their physical and operational characteristics and regions of application rather than their theory of operation. Magnetrons, linear beam tubes, split-cavity oscillators, virtual cathode oscillators, gyrotrons, free-electron lasers, and orbitron microwave masers are described. Power supply requirements and engineering issues of the application of HPM devices are addressed.

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The split-cavity oscillator: a high-power E-beam modulator and microwave source

Cited by 83 publications

References 15 publications

Conversion efficiency in axial monotrons

Conversion efficiency in axial monotrons

A Ku-band coaxial relativistic transit-time oscillator with low guiding magnetic field

A Brief Technology Survey of High-Power Microwave Sources

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