Expressions for the Threshold Current of Multipass Beam Breakup in Recirculating Linacs from Single Cavity Models PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Expressions for the Threshold Current of Multipass Beam Breakup in Recirculating Linacs from Single Cavity Models PDF full book. Access full book title Expressions for the Threshold Current of Multipass Beam Breakup in Recirculating Linacs from Single Cavity Models by . Download full books in PDF and EPUB format.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We investigate multipass beam breakup (BBU) in a recirculating linear accelerator in the framework of a single cavity model. We present expressions for the beam breakup threshold current for various situations derived from a perturbative solution of BBU equations. These formulae should serve as a guide to understand the BBU phenomenon for a particular system and also as a tool to estimate the BBU threshold current quickly. Many of the results presented are more general than previous considerations because they include the effects of coupling between the two transverse polarizations in each dipole higher order mode.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We investigate multipass beam breakup (BBU) in a recirculating linear accelerator in the framework of a single cavity model. We present expressions for the beam breakup threshold current for various situations derived from a perturbative solution of BBU equations. These formulae should serve as a guide to understand the BBU phenomenon for a particular system and also as a tool to estimate the BBU threshold current quickly. Many of the results presented are more general than previous considerations because they include the effects of coupling between the two transverse polarizations in each dipole higher order mode.
Author: Publisher: ISBN: Category : Languages : en Pages : 2060
Book Description
Multipass beam breakup, a transverse beam instability generated by coherent excitation of cavity higher order modes in a recirculating linac, is a particular concern in designs utilizing superconducting technology. In this paper, an analytic model is presented that includes a description of this effect for a distribution of cavities along the linac with several recirculations in an impulse approximation. For N passes and M cvities, solution of the resulting equations reduces in general to finding M zeros of a 2(N-1) dimensional determinant or equivalently the M eigenvalues of an M-dimensional matrix. The parametric dependence of this system on higher order mode frequencies and Q, lattice functions, and transit times is discussed. Numerical examples are presented to clarify these issues and to model the CEBAF superconducting linac, where threshold currents are found to exceed design currents by more than an order of magnitude.
Author: Publisher: ISBN: Category : Languages : en Pages : 2483
Book Description
In general, a recirculation path length in a recirculating accelerator has to be an integer multiple of RF wavelength if recirculations are all in the same direction. However, it is not necessary to require such a relation to be satisfied with respect to the bunching frequency, when the bunch repetition rate is different from the RF frequency. An analytic model of multipass beam breakup (BBU) in recirculating linacs studied by Bisognano and Gluckstern has been generalized to include the case of a subharmonic bunching scheme in the operation of such linacs.
Author: Publisher: ISBN: Category : Languages : en Pages : 15
Book Description
We describe here a study of a single bunch Beam Break Up (BBU) instability for a proposed Berkeley fast x-ray facility based on a recirculating linac [1]. The recirculating linac employs a 600 MeV superconducting RF linear accelerator and the electron beam energy of H"2.5 GeV is reached over four beam passes through the linac. A 120 MeV superconducting RF linear accelerator is used as an injector to the recirculating linac. The machine parameters are listed in Appendix A. The equation describing the transverse displacement x(s, z) of the electrons in an accelerated bunch, as a function of their longitudinal position within the bunch z, can be written in the form [2]: d/ds[[gamma](s) dx/ds] + k2(s)[gamma](s)x(s, z) = r0+"sub z}{sup {infinity}}[rho](z')W{sub {perpendicular}}(z'-z)x(s, z')dz' (1) where [gamma] is the relativistic factor, k the focusing strength, r0 the classical electron radius, [rho] the bunch density, W{sub {perpendicular}} the transverse wake function per unit length and s indicates the position along the linac. We assume infinitesimally small transverse beam dimensions (a good approximation, when the bunch dimensions are much less than the size of the beam pipe), so that x has to be interpreted as the displacement of the centre of a bunch slice. We also assume a bunch length much less than the betatron wavelength, therefore the displacement in the RHS of Eq.(1) is not retarded and, finally, we use an average transverse wake function obtained averaging the calculated short range wake of a single cavity [2] over the linac length. At first we consider the effect associated with a displacement of the electron bunch at the injection into the perfectly aligned linac. Later we extend the analysis to the case of misalignments of the linac RF cavities and cryomodules. Throughout the paper we compare the results obtained to the output of a simple tracking code, written as a Mathematical notebook. In order to keep the analytical expressions reasonably simple, we model the linac length as entirely filled with RF cavities (thus neglecting all the drift spaces, accounting for as much as one third of the total length). This causes the wakefield intensity used in the analysis to be bigger than the actual value and the average accelerating gradient to be smaller. It is shown in the paper that this corresponds to a conservative estimate of the BBU growth.
Author: 
Author: 
Author: 
Author: 
Author: 
Author: 
Author: Eric R. Lindstrom
Author: Joseph J. Bisognano
Author: 
Author: Ilkyoung Shin
Author: