Related papers: Space charge impedances of a rectangular beam with…
We propose and analyze in detail a method to measure the in-air spatial spread parameter of clinical electron beams. Measurements are performed at the center of the beam and below the adjustable collimators sited in asymmetrical…
In particle accelerators, pumping holes in a vacuum chamber can be a source of unwanted broadband coupling impedance, leading to beam instabilities. Analytical methods have been previously developed to estimate the impedance of holes in…
A general derivation of the beam coupling impedances produced by small discontinuities on the wall of the vacuum chamber of an accelerator is reviewed. A collection of analytical formulas for the impedances of small obstacles is presented.
The working of a resistive plate chamber depends on the electric field applied inside the gas gap. The strength of this electric field inside the gas gap depends on parameters like electrode thickness, permittivity, gas gap, among others.…
An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The…
Flat beams are preferred in high-intensity accelerators and high-energy colliders due to one of the transverse plane emittances being much smaller than the other, which enhances luminosity and beam brightness. However, flat beams are not…
The beam coupling impedances of small axisymmetric obstacles having a semi-elliptical cross section along the beam in the vacuum chamber of an accelerator are calculated at frequencies for which the wavelength is large compared to a typical…
The upgrade project of Hefei Light Source storage ring is under way. In this paper, the broadband impedances of resistive wall and coated ceramic vacuum chamber were calculated using the analytic formula, the wake fields and impedances of…
An analytical method is developed for calculating the geometric wakefield and impedances of an ultrarelativistic beam propagating on- and off-axis through an axially symmetric geometry with slowly varying circular cross-section, such as a…
As an extension of previous theoretical study on the coherent structure resonance due to space charge effects [Chao Li and R. A. Jameson, Phys. Rev. Accel. Beams 21, 024204, 2018], this paper aims to demonstrate how the beam, as a whole, is…
The microbunching instability usually exists in the LINAC of a free electron laser (FEL) facility. In many cases, the longitudinal space charge (LSC) is a dominant factor that generates the instability. For the highly bright electron beams,…
Resistive plate chamber (RPC) is one of the state-of-the-art particle detection technology for the High Energy Physics (HEP) experiments. The basic operating mechanism of an RPC involves ionization of gas due to the passage of charged…
For modern high-intensity linear accelerators, the well-known envelope instability and recently reported fourth-order particle resonance impose a fundamental operational limit (i.e., zero-current phase advance should be less than 90 deg).…
Coulomb fields of charged particle beams in circular machines determine, together with wake fields, modes of the collective beam oscillations, both for transverse and longitudinal degrees of freedom. Recent progress in these two areas of…
We study how the initial inhomogeneities of the spatial curvature affect the onset of inflation in the closed universe. We consider a cosmological model which contains a radiation and a cosmological constant. In order to treat the…
The spatial inhomogeneities are expected to affect nucleation process in an essential way. These effects are studied theoretically by considering the case of the depinning of the charge density wave as a typical example. The threshold field…
Proposed, justified and tested measuring of beam spatial coherence, based on the detection of an interference visibility of the equal to intensity of beam replicas emerging under reflection from the rotated plane-parallel plate. The method…
Both horizontal and vertical coherent beam-beam instability are important issues at CEPC. The horizontal instability (X-Z instability) could be induced by beam-beam itself. In this paper we try to study the effect of chromaticity and…
The space charge limited emission of ions from a target in the focus of an intense relativistic electron beam is studied analytically for the case of a spatially varying target density profile. In particular, the emission in the presence of…
The operation and parameters of Bunch Shape Monitors using coherent transformation of time structure of an analyzed beam into a spatial one of low energy secondary electrons emitted from a wire target is influenced by the characteristics of…