Low-frequency azimuthally propagating (diocotron) waves in a non-neutral electron beam column

Chen, K. W.; Kim, S. H.; McKinley, M. C.

doi:10.1063/1.866461

Cited by 3 publications

(1 citation statement)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The diocotron wave is an electrostatic (ES) wave associated with a plasma density fluctuation which cannot be described with single-electron dynamics. The most perspicuously recognized feature of the diocotron wave is the rotation characteristics of the l = 1 diocotron wave and is inarguably observed even in low-density (n 6 10 7 cm −3 ) and low-velocity (v 0.001c) electron beam (Chen et al 1987).…”

Section: Long-range Coulomb Forcementioning

confidence: 99%

Maser gain determined by the spatial profile of work done by an average electron and the wavelength of density fluctuation driven by the maser field in multi-photon free-electron two-quantum Stark radiation

Kim

2015

J. Plasma Phys.

Self Cite

View full text Add to dashboard Cite

We find that the electron in an electron–cyclotron maser (ECM) of Nc = n1/3λ ≫ 1, where n and λ are the electron density and the maser wavelength, respectively, can only lower its energy through masing transition. From this fact and the application of Heisenberg's uncertainty principle on photon emission, we infer that until the electron energy becomes lower to pass through the width of uncertainty in the electron energy, the interval time Tint between two successive radiative transitions is zero. Hence, we find that if the number Nt of radiative transitions during the laser period T under the assumption of Tint = 0 is far larger than the number Nu of radiative transitions required to pass through the half-width ΔE of uncertainty in the electron energy, the radiation power from an electron is equal to ΔE/T. We deduce that the shift in the energy level of an average electron is predominantly produced by the density-deviation mode driven by the laser field so as to be spatially sinusoidal with period λw and amplitude $\mathcal W$. We recognize that the uncertainty in the z position of an electron emitting a laser photon through free-electron two-quantum Stark (FETQS) radiation is the wavelength λe of the electric wiggler. Thus, if λw ≪ λe, then ΔE is equal to $\mathcal W$. Based on the above findings, we identify electron–cyclotron masing in a high-density ECM as a gyration-driven FETQS radiation whose power is given by P = ΔE/T, where ΔE is not caused by gyration but rotation around the waveguide axis. The gain calculated based on this identification agrees with the measured one.

show abstract

Section: Long-range Coulomb Forcementioning

confidence: 99%

Maser gain determined by the spatial profile of work done by an average electron and the wavelength of density fluctuation driven by the maser field in multi-photon free-electron two-quantum Stark radiation

Kim

2015

J. Plasma Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

Excitation of Surface Flute Waves in Electron Cyclotron Frequency Range by Relativistic Electron Beam Gyrating Along Large Larmor Orbits

Гірка

Thumm

2022

Surface Flute Waves in Plasmas

View full text Add to dashboard Cite

Structure and damping of toroidal drift waves (and their implications for anomalous transport)

Taylor

Connor

Wilson

1993

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

The conventional theory of high-n toroidal drift waves, based on the ballooning representation, indicates that shear-damping is generally reduced in a torus compared to its plane-slab value. It therefore describes the most unstable class of toroidal drift waves, ttowever, modes of this type occur only if the diamagnetic frequency w*(r) has a maximum in r, and they affect only a small fraction, O(1/n 1/2), of the plasma radius around this mazdmum. Consequently they may produce little anomalous transport. In the present work we show that, within the ballooning description, there is another class of toroidal drift waves with very different properties to the conventional ones. The new modes have greater shear-damping (closer to that in a plane-slab) than the conventional ones and so have a higher instability threshold. However, they occur for any plasma profile and at all radii, and they have larger radial extent. Consequently they may produce much greater anomalous transport than the possibly benign conventional modes. This suggests a picture of anomalous transport in which the plasma profile is determined by marginal stability, but marginal to the new class of modes not to the conventional ones. This might explain why marginally stable profiles calculated for drift waves with plane-slab damping sometimes agree well with the profiles in toroidal experiments. It is also consistent with the fact that experimental profiles may exceed conventional toroidal instability thresholds. The new modes may also be related to the long radial structures which appear in some plasma simulations and in experiments.

show abstract

Low-frequency azimuthally propagating (diocotron) waves in a non-neutral electron beam column

Cited by 3 publications

References 9 publications

Maser gain determined by the spatial profile of work done by an average electron and the wavelength of density fluctuation driven by the maser field in multi-photon free-electron two-quantum Stark radiation

Maser gain determined by the spatial profile of work done by an average electron and the wavelength of density fluctuation driven by the maser field in multi-photon free-electron two-quantum Stark radiation

Excitation of Surface Flute Waves in Electron Cyclotron Frequency Range by Relativistic Electron Beam Gyrating Along Large Larmor Orbits

Structure and damping of toroidal drift waves (and their implications for anomalous transport)

Contact Info

Product

Resources

About