Free-electron lasers with magnetized ion-wiggler

Mehdian, H.; Jafari, S.; Hasanbeigi, Ali; Ebrahimi, Farshad

doi:10.1016/j.nima.2009.03.057

Cited by 6 publications

(5 citation statements)

References 28 publications

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“…During the bounce period, the unstable electromagnetic waves continue to grow to overshoot. This overshoot of the wave amplitudes results in further energy deposition into the electromagnetic radiation [33,49]. The axial guide magnetic field has a two-fold purpose.…”

Section: Numerical Results and Conclusionmentioning

confidence: 99%

“…The form of the interaction can be classified in a variety of ways depending upon such parameters as the magnitude of the electron current, the strength of the pump field, the bulk energy and energy spread of beam and the length of the interaction region. Thermal effects can be neglected when the energy spread in the beam E E 0 /N , where E 0 is the bulk beam energy and N is the number of wiggler periods in the interaction region [33,37]. An additional factor in the interaction is brought about by practical limitations in the propagation of intense electron beams, specifically that an axial guide magnetic field is required to collimate intense beams in the transverse direction [38].…”

Section: Physical Model and Assumptionsmentioning

confidence: 99%

“…in helical wiggler, <50 kG), a conventional FEL needs a very high-γ electron beam to generate a short wavelength (λ ∼ 500 Å) and to operate there with a low efficiency. This increases many beam requirements: higher energy, higher current and higher quality as well as the magnet requirements of stronger and more precise magnetic field, very accurate wiggler wavelengths and alignment [33,39]. By employing a DPC wiggler, the wiggler wavelength can be shorter and can easily be adjusted.…”

Section: Physical Model and Assumptionsmentioning

confidence: 99%

“…When the pump electric field is oriented perpendicular to the direction of beam propagation, the physical situation is much the same as for magnetic wigglers; in both systems, axial electron bunching necessary for wave amplification comes about via the radiation pressure force, i.e. the ponderomotive force; the electrical pump field E ⊥ in the electrically excited system plays the same role as the magnetic pump field B ⊥ = E ⊥ /c in the magnetic wiggler system [32,33]. Coherent radiation depends upon the stimulated emission due to the ponderomotive wave formed by the beating of the radiation and wiggler fields.…”

Section: Introductionmentioning

confidence: 99%

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Generation of stimulated emission from a relativistic beam by magnetized dusty plasma crystals (DPCs)

Mehdian¹,

Jafari²,

Hasanbeigi³

2010

Plasma Phys. Control. Fusion

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Micrometer-sized dust particles become highly charged when suspended in a plasma. Because of mutual repulsion and the plasma's weaker radial electric fields (usually produced by physically modifying the lower electrode in a rf chamber), they arrange themselves in a structure known as a plasma crystal. Stimulated emission by an accelerated electron beam propagating through a dusty plasma crystal (DPC), acting as a DPC wiggler, is studied. The period of these structures can be extremely short (of the order of hundreds of micrometers) which leads to the possible reduction in the electron beam energy necessary to produce a shorter wavelength. The laser gain in the low-gain-per-pass limit is calculated for a cold beam embedded in an external magnetic field. Numerical computations of the electron trajectories and small-signal gain are presented. It is shown that the DPC wiggler can provide a simple system with high frequency output and output power at relatively modest energies. In many situations it can be superior to conventional wigglers in beam devices.

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Section: Numerical Results and Conclusionmentioning

confidence: 99%

Section: Physical Model and Assumptionsmentioning

confidence: 99%

Section: Physical Model and Assumptionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Generation of stimulated emission from a relativistic beam by magnetized dusty plasma crystals (DPCs)

Mehdian¹,

Jafari²,

Hasanbeigi³

2010

Plasma Phys. Control. Fusion

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“…By passing a relativistic e-beam through a magnetized plasma channel, high-frequency electromagnetic radiation is generated by coupling the electromagnetic wave to the negative energy electrostatic beam modes. The negative energy electrostatic beam mode and the positive energy electromagnetic wave can strongly couple together, leading to an instability [34,35]. During the course of the instability, the amplitudes of beam modes increases and the waves begin to trap electrons.…”

Section: Introductionmentioning

confidence: 99%

Free-electron laser with a plasma wave wiggler propagating through a magnetized plasma channel

Jafari¹,

Jafarinia²,

Mehdian³

2013

Laser Phys.

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A plasma eigenmode has been employed as a wiggler in a magnetized plasma channel for the generation of laser radiation in a free-electron laser. The short wavelength of the plasma wave allows a higher radiation frequency to be obtained than from conventional wiggler free-electron lasers. The plasma can significantly slow down the radiation mode, thereby relaxing the beam energy requirement considerably. In addition, it allows a beam current in excess of the vacuum current limit via charge neutralization. This configuration has a higher tunability by controlling the plasma density in addition to the γ-tunability of the standard FEL. The laser gain has been calculated and numerical computations of the electron trajectories and gain are presented. Four groups (I–IV) of electron orbits have been found. It has been shown that by increasing the cyclotron frequency, the gain for orbits of group I and group III increases, while a decrease in gain has been obtained for orbits of group II and group IV. Similarly, the effect of plasma density on gain has been exhibited. The results indicate that with increasing plasma density, the orbits of all groups shift to higher cyclotron frequencies. The effects of beam self-fields on gain have also been demonstrated. It has been found that in the presence of beam self-fields the sensitivity of the gain increases substantially in the vicinity of gyroresonance. Here, the gain enhancement and reduction are due to the paramagnetic and diamagnetic effects of the self-magnetic field, respectively.

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Linear theory of magnetized ion-channel free-electron laser

Sadegzadeh¹,

Hasanbeigi²,

Mehdian³

et al. 2012

Physics of Plasmas

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A theory of wiggler pumped ion-channel free-electron laser (WPIC-FEL) and an axial magnetic field is presented. The motion of a relativistic electron is analyzed in the field configuration consisting of a helical wiggler magnetic field, a uniform axial magnetic field, and an electrostatic electric field produced by an ion-channel. An equation for the function Φ, which determines the rate of change of axial velocity with energy, is derived. Numerical calculations are made to illustrate the effects of two electron beam guiding devices on the trajectories. By means of linear fluid theory, the sixth-degree polynomial dispersion equation for electromagnetic and space-charge waves is derived. The dependence of growth rate-frequency curves on the ion-channel frequency and axial magnetic field is studied numerically.

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Free-electron lasers with magnetized ion-wiggler

Cited by 6 publications

References 28 publications

Generation of stimulated emission from a relativistic beam by magnetized dusty plasma crystals (DPCs)

Generation of stimulated emission from a relativistic beam by magnetized dusty plasma crystals (DPCs)

Free-electron laser with a plasma wave wiggler propagating through a magnetized plasma channel

Linear theory of magnetized ion-channel free-electron laser

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