Beam Coupling Impedances of Obstacles Protruding into Beam Pipe

The beam coupling impedances of small obstacles protruding inside the vacuum chamber of an accelerator are calculated analytically at frequencies for which the wavelength is large compared to a typical size of the obstacle. Simple formulas for a few important particular cases, including both essentially three-dimensional objects like a post or a mask and axisymmetric irises, are presented. The analytical results are compared and agree with three-dimensional computer simulations. These results allow simple practical estimates of the broad-band impedance contributions from such discontinuities.Comment: 4 pages, LaTeX (REVTeX), 2 figures (eps); corrected and revised, comparison with simulations added; presented at PAC97 (Vancouver, May 97

Notes on beam dynamics in linear accelerators

A collection of notes, on various aspects of beam dynamics in linear accelerators, which were produced by the author during five years (1975 to 1980) of consultation for the LASL Accelerator Technology (AT) Division and Medium-Energy Physics (MP) Division is presented

Scalar potential for charge distributions with ellipsoidal symmetry

Calculation of the electrostatic scalar potential in ellipsoidal coordinates is outlined. The ellipsoidal coordinate system is described, and the Laplace equation is discussed for this system. Special charge distributions having ellipsoidal symmetry, and therefore most easily treated in ellipsoidal coordinates, are assumed and their scalar potentials calculated, including the ellipsoidal shell, two-dimensional and three-dimensional Gaussian charge distribution, and two-dimensional uniform distribution. 2 refs. (LEW

Width of nonlinear difference resonances

A definition is proposed in which the concept of ''acceptable'' growth in emittance plays the essential role. A numerical table is given for some combinations of p and q which are likely to be of practical interest. 4 refs., 4 figs., 1 tab. (GHT