The electron cyclotron maser

Chu, K. R.

doi:10.1103/revmodphys.76.489

Cited by 552 publications

(238 citation statements)

References 174 publications

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“…21,23,28 A review of the theory with experimental results and many references dedicated to the study of nonstationary regimes in gyrotrons can be found in Chu. 12 The gyrotron system used in this work has been designed with the aim of maximizing its frequency tunability via longitudinal mode competition for dynamic nuclear polarization (DNP)-nuclear magnetic resonance (NMR) applications. 3,25 The uncoupled dispersion relation for the gyrotron system parameters is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Experimental study from linear to chaotic regimes on a terahertz-frequency gyrotron oscillator

et al. 2012

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Basic wave-particle interaction dynamics from linear to chaotic regimes is experimentally studied on a frequency tunable gyrotron generating THz radiation in continuous mode (200 W) at 263 GHz which will be used for dynamic nuclear polarization nuclear magnetic resonance spectroscopy applications. In the studied system, the nonlinear dynamics associated to the waveparticle interaction is dominated by longitudinal mode competition of a given transverse TE m;p cavity-mode. This study covers a wide range of control parameter from gyro-traveling wave tube (gyro-TWT) to gyro-backward wave oscillator (gyro-BWO) like interactions for which extensive theoretical studies have been performed in the past on a simplified system. Besides the common route to chaos characterized by period doubling, other routes have been identified among which some are characterized by line-width frequency-broadening on the side-bands. The complex nonlinear dynamics is in good agreement with the theory and the experimental results are discussed on the basis of the prediction obtained with the nonlinear time-dependent selfconsistent codes TWANG and EURIDICE both based on a slow-time scale formulation of the self-consistent equations governing the wave-particle dynamics. V C 2012 American Institute of Physics. [http://dx

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Section: Introductionmentioning

confidence: 99%

Experimental study from linear to chaotic regimes on a terahertz-frequency gyrotron oscillator

et al. 2012

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“…The charged particles, through their interaction, can collectively exchange energy and momentum with the waves. In accelerators particles gain energy from the electromagnetic fields, while in microwave sources and amplifiers energetic electrons give up some fraction of their energy to waves [5]. In fusion plasmas, radio frequency waves are used to heat the plasma, and also to generate currents in plasmas by imparting momentum to particles.…”

Section: Introductionmentioning

confidence: 99%

Interaction of charged particles with localized electrostatic waves in a magnetized plasma

2012

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Charged particle interaction with localized wave packets in a magnetic field is formulated using the canonical perturbation theory and the Lie transform theory. An electrostatic wave packet characterized by a wide range of group and phase velocities as well as spatial extent along and across the magnetic field is considered. The averaged changes in the momentum along the magnetic field, the angular momentum, and the guiding center position for an ensemble of particles due to their interaction with the wave packet are determined analytically. Both resonant and ponderomotive effects are included. For the case of a Gaussian wave packet, closed-form expressions include the dependency of the ensemble averaged particle momenta and gc position variations on wave packet parameters and particle initial conditions. These expressions elucidate the physics of the interaction which is markedly different from the well known case of particle interaction with plane waves and are relevant to a variety of applications ranging from space and astrophysical plasmas to laboratory and fusion plasmas as well as accelerators and microwave devices.

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“…and even in the vacuum electronic devices, such as, linear/particle accelerators [11,12], backward-wave oscillators (BWOs) [13], magnetrons [14], coupledcavity and helix travelling-wave tubes (TWTs) [15][16][17][18][19], cyclotron masers [20,21], gyrotron sources [21][22][23][24] and amplifiers [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], etc.. In these devices, one may see the periodic beam-wave interaction structures holding either azimuthal or axial periodicity [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]…”

Section: Introductionmentioning

confidence: 99%

“…In these devices, one may see the periodic beam-wave interaction structures holding either azimuthal or axial periodicity [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. The azimuthal periodicity in interaction structure may be seen, for example: in travelling-wave magnetrons [14] for π-mode operation, in gyrotrons [21][22][23][24] for mode rarefaction, in conventional helixTWTs [17] for broadbanding, in gyro-travelling wave tubes (gyroTWTs) [25,26] for higher interaction impedance and, in turn, for higher device-gain. The axial periodicity in interaction structure may be seen, for example, in conventional helix-TWT [17] for higher device-gain, in coupled-cavity TWT [17] for getting fundamentalmode backward-wave characteristics, and in gyro-TWT [27][28][29][30][31][32][33][34][35][36][37][38][39] for broadbanding.…”

Section: Introductionmentioning

confidence: 99%

Propagation Characteristics of a Variant of Disc-Loaded Circular Waveguide

Kesari¹,

Keshari²

2012

PIER M

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Abstract-The shaping of dispersion characteristics in a variant of disc-loaded circular waveguide was studied through electromagnetic analysis for assessing the structure for wideband coalescence of the beam-and waveguide-mode dispersion characteristics that entails the wideband gyro-travelling-wave tube (gyro-TWT) performance. In this variant of disc-loaded circular waveguide, the alternate dischole radii were varying, however, the structure was periodic. The structure periodicity coupled with Floquet's theorem and fieldmatching technique resulted into the dispersion relation of the infinitely long structure. A numerical code was developed to solve the dispersion relation, and the dispersion characteristics of the structure were analyzed for the azimuthally symmetric TE-modes. The effects of structure parameters were studied for getting a straight-line portion of the dispersion characteristics over a wide frequency range. The dispersion shaping was projected for typically chosen TE 01 -mode. The results were validated against those obtained for the conventional and un-conventional known structures and those obtained using commercially available simulation tool. The variation of azimuthal electric field intensity over the radial coordinate was also studied to examine the control of structure parameter for maxima-position, where the gyrating electron beam would be positioned for optimum beamwave interaction in a gyro-TWT.

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The electron cyclotron maser

Cited by 552 publications

References 174 publications

Experimental study from linear to chaotic regimes on a terahertz-frequency gyrotron oscillator

Experimental study from linear to chaotic regimes on a terahertz-frequency gyrotron oscillator

Interaction of charged particles with localized electrostatic waves in a magnetized plasma

Propagation Characteristics of a Variant of Disc-Loaded Circular Waveguide

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