Search Results (2 total)

Extending the method of Warnock and Ellison for the simulation of the Vlasov-Fokker-Planck equation for bunched beams [in Proceedings of the 2nd ICFA Advanced Accelerator Workshop on the Physics of High Brightness Beams, Los Angeles, CA, 1999 (World Scientific, Singapore, 2000)], we analyze arbitrary radio-frequency potentials and high- Q impedances and study instabilities in stretched bunches. Results for the microwave instability driven by a broadband impedance and instability driven by high- Q rf modes in stretched bunches are compared with measurements of the vacuum ultraviolet ring at the National Synchrotron Light Source. A method for the calculation of response functions is developed, and simulated response functions are compared to experimental results.

A mode of coherent longitudinal dipole motion of the beam in the National Synchrotron Light Source (NSLS) vacuum ultraviolet (vuv) ring with small frequency is observed by Biscardi et al. [Rev. Sci. Instrum. 66, 1856 (1995)]. We point out in this paper that the coherent motion observed is, although a solution to the well-known secular equation for Robinson instability, a distinct mode of beam dipole motion from what is normally known as the Robinson mode. In this paper the mode’s properties and its relationships with the usual Robinson mode are developed. The collision of the two modes is understood analytically and observed experimentally in the NSLS vuv ring.