DYNAMICS OF PLASMA EXCITED BY THE PERIODIC SEQUENCE OF RELATIVISTIC ELECTRON BUNCHES

Wake wave excited by the resonant sequence of electron bunches grows to high amplitude after passage of several bunches. As electron bunches are injected into plasma at the same point, it results to high-amplitude plasma oscillations at the limited area in the plasma volume. Relaxation of the wake wave causes plasma heating via Landau damping. It moves to background plasma pressing-out from this area. So plasma density spatial distribution is disturbed. Such density profile deformation causes plasma frequency deviation, so that initial Cherenkov resonance is broken. Local plasma density decreases almost linearly with time. Front of the density perturbation has the shape similar to collision less shock wave.

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Plasma Damping of Gravitational Waves

Symposium - International Astronomical Union ◽

10.1017/s007418090008774x ◽

1990 ◽

Vol 142 ◽

pp. 62-62

Author(s):

C. Sivaram

Keyword(s):

Neutron Star ◽

Magnetic Fields ◽

Gravitational Waves ◽

Plasma Frequency ◽

Landau Damping ◽

Plasma Medium ◽

Plane Gravitational Waves

The possibility of the damping of plane gravitational waves while propagating in a plasma medium is considered. The gravitational plasma frequency, is for a neutron star medium ~ 103Hz, which is the same as the frequency of the gravitational waves emitted by a collapsing star. So resonant damping of such waves within a collapsing star is probable. Estimates are made for the damping length for dense and dilute plasmas (also in the presence of magnetic fields). Analogies with Landau damping are made. Applications to other astrophysical situations are outlined.

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Acceleration of nonmonoenergetic electron bunches injected into a wake wave

Journal of Experimental and Theoretical Physics ◽

10.1134/s1063776112050044 ◽

2012 ◽

Vol 115 (1) ◽

pp. 171-183 ◽

Cited By ~ 3

Author(s):

S. V. Kuznetsov

Keyword(s):

Electron Bunches ◽

Wake Wave

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Plasma-Density-Gradient Injection of Low Absolute-Momentum-Spread Electron Bunches

Physical Review Letters ◽

10.1103/physrevlett.100.215004 ◽

2008 ◽

Vol 100 (21) ◽

Cited By ~ 250

Author(s):

C. G. R. Geddes ◽

K. Nakamura ◽

G. R. Plateau ◽

Cs. Toth ◽

E. Cormier-Michel ◽

...

Keyword(s):

Density Gradient ◽

Plasma Density ◽

Momentum Spread ◽

Electron Bunches

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The growth and decay of resonant plasma oscillations excited by a small pulsed dipole

Journal of Plasma Physics ◽

10.1017/s0022377800004335 ◽

1969 ◽

Vol 3 (2) ◽

pp. 227-241 ◽

Cited By ~ 11

Author(s):

J. A. Fejer ◽

Wai-Mao Yu

Keyword(s):

Time Delays ◽

Cyclotron Frequency ◽

Plasma Frequency ◽

Practical Interest ◽

Observation Point ◽

Landau Damping ◽

Plasma Oscillations ◽

Fixed Distance ◽

The Mean ◽

Thermal Speed

The application of integration by the method of stationary phase to resonant oscillations excited by a small pulsed dipole is outlined. Both the growth and the decay of the oscillations near the plasma frequency are determined by this method at a fixed distance from the dipole, first in the absence and then in the presence of an external magnetic field. It is shown that Landau damping must be taken into account in the calculation of the growth but not of the decay. The oscillations are shown to spread out with a speed that is about half the mean thermal speed of electrons.Only the decay, not the growth, of the oscifiations near harmonics of the cyclotron frequency can be calculated by the same method. It is shown, moreover, that the amplitude, calculated for an observation point that moves away with sateffite velocity in an ionospheric environment, is only valid for time delays longer than about a minute. Such a result is therefore of no practical interest because the resonances observed from sateffites only last a few milliseconds. The erroneous nature of using such a result and the need for a different approach, such as that used in earlier work by the first author, are thus demonstrated.

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Plasma wake-field excitation by relativistic electron bunches and charged particle acceleration in the presence of external magnetic field

Laser and Particle Beams ◽

10.1017/s0263034601194061 ◽

2001 ◽

Vol 19 (4) ◽

pp. 597-604 ◽

Cited By ~ 14

Author(s):

V.A. BALAKIREV ◽

V.I. KARAS' ◽

I.V. KARAS' ◽

V.D. LEVCHENKO

Keyword(s):

Magnetic Field ◽

Relativistic Electron ◽

Magnetoactive Plasma ◽

High Amplitude ◽

Plasma Dynamics ◽

Wake Field ◽

Electron Bunches ◽

Plasma Bunch ◽

Field Excitation ◽

Wake Fields

High-amplitude plasma wake waves are excited by high-density relativistic electron bunches (REB) moving in a plasma. The wake-fields can be used to accelerate charged particles, to serve as electrostatic wigglers in plasma free-electron lasers (FEL), and also can find many other applications. The electromagnetic fields in the region occupied by the bunch control the dynamics of the bunch itself. This paper presents the results of 2.5-dimensional numerical simulation of the modulation of a long REB in a plasma, the excitation of wake-fields by bunches in a plasma, in particular, in magnetoactive plasma. The previous one-dimensional study has shown that the density-profile modulation of a long bunch moving in plasma results in the growth of the coherent wake-wave amplitude. The bunch modulation occurs at the plasma frequency. The present study is concerned with the REB motion, taking into account the plasma and REB nonlinearities. It is demonstrated that the nonlinear REB/plasma dynamics exerts primary effect on both the REB self-modulation and the wake-field excitation by the bunches formed. We have demonstrated that a multiple excess of the accelerated bunch energy εmax over the energy of the exciting REB is possible in a magnetoactive plasma for a certain relationship between the parameters of the “plasma–bunch–magnetic field” system (owing to a hybrid volume–surface character of REB-excited wake-fields).

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ACCELERATING OF THE ELECTRONS OF ELECTRON BUNCHES IN A WAVEGUIDE LOADED DIELECTRIC STRUCTURE

10.46813/2021-136-067 ◽

2021 ◽

pp. 67-71

Author(s):

A.F. Linnik ◽

I.N. Onishchenko ◽

O.L. Omelayenko ◽

V.I. Pristupa ◽

G.V. Sotnikov ◽

...

Keyword(s):

Experimental Studies ◽

Bunch Length ◽

Dielectric Structure ◽

Steady State Mode ◽

Electron Bunches ◽

Simple Physical Model ◽

Wake Wave ◽

The Difference ◽

Wake Fields ◽

Dielectric Structures

The paper presents some results of experimental studies of the excitation of wake fields and the acceleration of electrons in waveguide-dielectric structures (DS) upon injection of a sequence of electron bunches into them. Exper-iments have shown an increase in the amplitude of the wake wave and the acceleration of a small fraction of elec-trons when the wavelength of the excited field is equal to the doubled bunch length. A simple physical model of the observed phenomenon is given. Also, the paper proposes a method for accelerating a part of each electron bunch in the steady-state mode of the resonator dielectric structure. Some of the electrons are “cut out” by the collimator and enter the accelerating phase of the previously excited wake wave. The wave is displaced due to the difference in the distances traveled by the wave and the accelerated part of the electrons.

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EVOLUTION OF THE WAKE WAVE EXCIDED BY THE SEQUENCE OF THE RELATIVISTIC ELECTRON BUNCHES

10.46813/2019-122-055 ◽

2019 ◽

pp. 55-58

Author(s):

O.K. Vynnyk ◽

I.O. Anisimov

Keyword(s):

Collisionless Plasma ◽

Plasma Waves ◽

Axially Symmetric ◽

Particle In Cell ◽

Wake Field ◽

Electron Bunches ◽

Density Maps ◽

Wake Wave ◽

Symmetric Geometry ◽

Pic Code

The amplitude of plasma waves, excited by the resonant sequence of electron bunches, saturates after passage of some number of bunches. This behavior was observed and simulated, using particle-in-cell code, but was not completely explained yet. Our study of this behavior was carried out via computer simulation, using modified PDP3 code − 2D3V PIC code for axially symmetric geometry and relativistic collisionless plasma. Simulation demonstrated that amplitude saturation was caused by the plasma pressing-out from the area of the most intensive wake field. This hypothesis has been verified by the obtained electrical and magnetic field spectra, temperature and density maps and density profile for various simulation times.

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Electromagnetic emission from laser wakefields in underdense magnetized plasmas

Journal of Plasma Physics ◽

10.1017/s002237781200027x ◽

2012 ◽

Vol 78 (4) ◽

pp. 421-427 ◽

Cited By ~ 6

Author(s):

Z. D. HU ◽

Z. M. SHENG ◽

W. J. DING ◽

W. M. WANG ◽

Q. L. DONG ◽

...

Keyword(s):

Plasma Frequency ◽

Electromagnetic Emission ◽

High Amplitude ◽

Particle In Cell ◽

Laser Propagation ◽

Laser Wakefield ◽

Cell Simulation ◽

Pass Through ◽

Underdense Plasma ◽

Electromagnetic Component

AbstractThe laser wakefield structure in a magnetized underdense plasma is studied analytically and numerically. Because of the DC magnetic field perpendicular to the laser propagation direction, an electromagnetic component appears in addition to the normal electrostatic component. This electromagnetic component can transmit partially into vacuum at the plasma–vacuum boundary as shown by particle-in-cell simulation. It is found that the emission has components both at the fundamental plasma frequency and its harmonics if the wakefield is driven at a high amplitude. Comparing with the emission at the plasma frequency, the harmonic emission depends weakly upon the density profile at plasma–vacuum boundary and it can pass through the boundary almost without energy loss, providing a new method for the diagnostic of wakefields.

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