Relativistic Particle Beam Research Articles

Interaction of a relativistic beam with an inhomogeneous electromagnetic wave

A theoretical analysis is made of the motion of a relativistic particle beam across an electromagnetic H01, wave propagating in a rectangular waveguide and across a TEM wave propagating in a symmetric open two-conductor line. Modulation of the transverse coordinates and the particle velocities is investigated. A study is made of the interaction between the beam and an inhomogeneous wave. It is shown that when the beam propagates through an inhomogeneous wave, the particle energy may be converted into the radiation energy. A comparison is made with the results of numerical calculations of the particle dynamics in a wave field.

Beam instability in a nonmonochromatic wave and the possibility of optical phase conjugation in a relativistic particle beam

It is shown that the phenomenon of optical phase conjugation is possible in a relativistic particle beam.

Comment on "Curvature instability of relativistic particle beams"

Comment on "Curvature instability of relativistic particle beams"

Curvature instability of relativistic particle beams.

We investigate the instability of curvature radiation of a relativistic beam of charged particles in a very strong curved magnetic field, which is of interest as a pulsar radiation mechanism. The conditions for growth are a fairly steep boundary at the outer edge of the beam and high frequencies meeting a non-WKB requirement. High growth rates are found.

Laser acceleration of particles using resonance inversions of the Cherenkov effect

The possibility of Cherenkov accelerator development for physics experiments in the 10 2–10 6 TeV range is discussed in connection with the realization of some practical schemes of Cherenkov effect inversion using both the transverse homogeneous magnetic field and several Cherenkov waves. The required fields of 10 −2–10 5 TV/m can be obtained by double inversion of the Cherenkov effect in conventional and artificial ionic media. Calculations of particle dynamics were made taking into account the Coulomb scattering and radiation losses. The possibility of ∼ 10 5 T magnetic fields generation by relativistic particle beams is also discussed.

A trap for Cherenkov light from a wide beam of relativistic particles

A system is proposed which makes it possible to trap Cherenkov light from a wide beam of relativistic particles.

The interaction of relativistic charged-particle beams with interstellar clouds

view Abstract Citations (27) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The interaction of relativistic charged-particle beams with interstellar clouds Rose, W. K. ; Guillory, J. ; Beall, J. H. ; Kainer, S. Abstract Collimated beams of relativistic particles are known to be emitted from radio-bright active galaxies and quasars. Recent observations suggest that similar phenomena may occur in the nuclear regions of Seyfert galaxies. Some of the consequences that result from the interaction of a beam of relativistic particles with interstellar clouds have been calculated for a plausible range of physical parameters. Resonant plasma waves, nonresonant plasma waves, and ion acoustic waves are excit as a relativistic electron, electron-positron, or electron-proton beam traverses an interstellar cloud. The wave energy levels are characterized by either oscillatory or (quasi) steady state solutions. Nonresonant plasma waves may add power law tails to the distribution function of the background plasma electrons. The presence of electron tails can lead to enhanced optical and UV line radiation. The beam loses energy primarily as a result of the collisionless excitation of plasma waves, inverse Compton radiation, and resistive heating. The calculations made are described and some of their implications for observations of active galactic nuclei are discussed. Publication: The Astrophysical Journal Pub Date: May 1984 DOI: 10.1086/162025 Bibcode: 1984ApJ...280..550R Keywords: Galactic Nuclei; Interstellar Gas; Molecular Clouds; Particle Beams; Plasma-Particle Interactions; Relativistic Particles; Active Galactic Nuclei; Active Galaxies; Beam Interactions; Charged Particles; Magnetohydrodynamic Stability; Quasars; Seyfert Galaxies; Astrophysics full text sources ADS |

Inversion symmetry of radio lobes in extragalactic sources

The collimated beams of relativistic particles ejected from the central engines of extragalactic radio sources are traced out by means of the jet-like features of nonthermal radio emission which are observed to extend up to a few hundred kiloparsecs1–4. These jets exhibit departures from linearity in a variety of ways. In some less luminous large radio galaxies, the jets show structures with a distinctive S-shaped bending (inversion symmetry) at distances of the order of 100 kpc from the galactic nucleus5–8. We propose here that such a sharp bending can result from interaction of the relativistic beam fluid with faint, rotating shells similar to those seen around some nearby galaxies9, and discuss the possible implications of this hypothesis.

Ion-supported tori and the origin of radio jets

While apparently supplying tremendous power to their extended radio-emitting regions, the nuclei of most radio galaxies emit little detectable radiation. It is proposed that at the centre of each is a spinning black hole surrounded by a torus of gas too hot and tenuous to radiate efficiently. The torus anchors magnetic fields which extract rotational energy from the hole in the form of two collimated beams of relativistic particles and fields. These in turn drive the observed radio jets and hot spots. A large supply of accreting gas is thus unnecessary and radio galaxies may be interpreted as starved quasars.

Is a bi-stable beam responsible for the complex radio structure of 3C133?

It is generally assumed that the extended lobes of radio emission found in many extragalactic sources are powered by oppositely directed supply beams of relativistic particles emanating from the central galactic nucleus1,2. The complexity and asymmetry of the structure in many sources has, however, led to speculation of a ‘flip-flop’ beam mechanism3,4 where energy is supplied alternately to each radio lobe. Recent high resolution observations of the radio structure of 3C133 reveal a complex structure in which rotation of the source axis may have uncovered evidence for such a bi-stable nature of the energy supply. There are, however, several difficulties in such an interpretation.

Twin-jets from the centres of galaxies

Conceivably, the centres of all massive galaxies emit continuous antipodal beams of relativistic particles. We shall argue that these beams consist of highly relativistic electrons and positrons. At formation, the beams plough a channel through the ambient medium; the swept-up matter repeatedly stalls the particles which thereby follow closely the ambient pressure gradient. Thereafter, when the relativistic beam particles traverse these swarms of swept-up filamentary matter, they are repeatedly forced to bypass individual filaments and radiate (in the direction of their instantaneous motion). This forward-peaked radiation pattern can explain the preferred one-sided-ness of the observed radio/optical/X-ray knots in the jets. Pressure confinement focusses the beams, and temporarily freezes the channels. Interaction with the intergalactic wind can bend the beams into the shape of a warpedU, on length scales above some 20 kpc. The observed morphologies of extragalactic radio sources find a common explanation.

Extremely relativistic electron–positron twin-jets form extragalactic radio sources

The extended extragalactic double radio sources—quasars, BL Lac-type-objects (blazars), and radio galaxies—are commonly interpreted as synchrotron sources in which extremely relativistic electrons gyrate in enhanced magnetic fields. The detection of narrow emission bridges between hot spots inside these sources and the centre of an intermediate galaxy has strongly favoured the existence of a continuous power-line feeding the extended source1,3,5. Such beams may be a universal phenomenon occurring in many—if not all—massive galaxies, including our own4. But whereas early interpretations involved low-frequency electromagnetic waves and/or relativistic particle beams, more recent work favoured non-relativistic (β <10−1) (refs 3, 6–8), or mildly relativistic (γ <10) (refs 9–11) bulk velocities for the power supply. In particular, non-relativistic bulk velocities c β have been derived from estimates of the involved kinetic energy densities u and mass densities ρ in the form β≍(2u/ρ)1/2. This can lead to large underestimates of β when ρ is derived from Faraday rotation and depolarization data, because the observed jets are likely to have a two-fluid structure, with light relativistic plasma streaming inside of heavy ‘walls’ of thermal matter, or traversing ‘swarms’ of heavy quasistatic filaments12. We suggest here that these beams consist of extremely relativistic electrons and positrons, of typical Lorentz factor γ ≳102.

Some limitations on the design of plane periodic electromagnets for undulators and free electron lasers

Undulators and free electron lasers are potentially important new sources of intense quasi-monochromatic or coherent radiation produced by the action of a periodic magnetic field on a beam of relativistic particles. It is shown that field variations in the transverse plane arise as a direct result of the periodic nature of the magnet and that this restricts the minimum period that can be obtained. A parameter is introduced to describe the field variation and itseffect on the linewidth of the output radiation. Magnetic field computations have been carried out for a range of magnet geometries and the results are compared with useful analytic approximations. The restrictions on reducing the magnet period are then examined in detail. Consideration is also given to the more pronounced saturation effects that occur in such periodic magnets.

Radial expansion of a self-pinched beam with distributed energy

The structure and radial expansion of a relativistic particle beam are calculated in the presence of Coulomb scattering. The beam is assumed to be self-pinched and paraxial, but to have a distribution in energy. For the case in which the beam energy spread is small enough to satisfy (βγ)minβ−1γ−1≳1/2, solutions are found in which the entire beam expands self-similarly at an exponential rate proportional to β−1γ−1, where β≡v/c, γ−2≡1−β2, and the bar denotes the average over γ. The beam profile is calculated exactly in this case. If the inequality is not satisfied, low-γ particles expand faster than the main beam, at an exponential rate proportional to (2βγ)−1. Approximate time-dependent solutions, including initial transients, are presented for both cases.

Effects of a gravitational wave on relativistic particles

The interaction of a gravitational wave with a beam of relativistic particles leads to effects which can be observationally significant. The author finds, that if a beam of monochromatic light is scattered by these particles, the frequency shift of the scattered photons, as seen by a stationary observer, undergoes fluctuations, due to the presence of the gravitational waves, which are larger than the amplitude of these by the particle Lorentz factor. The actual motion of the beam under the effect of a train of gravitational waves is discussed.

Adiabatic equations of state for intense relativistic particle beams

Adiabatic equations of state for scalar pressure and anisotropic diagonal pressure have been obtained for intense, relativistic, unneutralized electron beams. These adiabatic equations of state complete the set of fluid equations needed to study beam dynamics and interactions from the fluid point of view. In particular, they facilitate the inclusion of thermal effects of momentum spread effects in stability analyses.

Statistical properties of double radio sources

We study a model of radio galaxies, where the galaxy is surrounded by an isothermal sphere of gas and the radio components move through this gas subsonically. Each radio component is assumed to be powered by either a supermassive particle accelerator, a head of a relativistic particle beam, or a train of plasmons. We find that the statistical properties involving the total size, radio luminosity, depolarization and symmetry of double radio sources can be explained independent of details of the radio source model.

Induced radiation of a beam of channeled relativistic particles

In principle, the possibility of producing a tunable laser on a beam of relativistic channeled particles is shown. A formula for the gain coefficient is obtained. A discussion is presented of the possibility of cooling the relativistic beam using channeling.

Langmuir Wave Phase Velocity in Unneutralized Beams

We investigate the dispersion relation for long wavelength slow Langmuir waves in a relativistic particle beam propagating along a strong magnetic guide field in an evacuated metallic waveguide. For a large class of beam radial profiles, wave phase velocity drops to zero with infinite slope as beam current approaches the space-charge limit. This result is of importance to certain collective ion acceleration proposals.

The Q-shift of off-center particle beams in elliptic vacuum chambers

The change of the betatron frequency of a relativistic particle beam - usually called Q-shift - due to the presence of material boundaries is calculated for elliptical geometries, including the limiting cases of circular and parallel plate geometries. The potential of a line charge anywhere in the elliptic chamber is found by conformal mapping, and the coherent and incoherent image coefficients are calculated from the second derivatives of the potential after subtraction of the direct space charge terms. The values of the image coefficients at the beam location itself are obtained by series development. The incoherent Q-shifts found from these formulae are used in the CERN Intersecting Storage Rings (ISR) for dynamic compensation of the working line during stacking of large beams.