Title :
Transverse coupling impedance of the VEPP-4M collider: measurements and simulations
Author :
Kiselev, V. ; Smaluk, V. ; Zorin, V.
Author_Institution :
Budker Inst. of Nucl. Phys., Novosibirsk, Russia
Abstract :
The main contribution into the total impedance of the VEPP-4M is made by places of non-uniformity of vacuum chamber, such as sharp change of cross section, ceramic inserts, vertical electrostatic separators and by HOMs of cavities. The computer code GdfidL is used for the estimate of impedances in some of above structures. A new method for measurement of transverse coupling impedance has been used. The method is based on measuring of the closed orbit deviation caused by localized impedance. Transverse impedance acts on the beam as a defocusing quadrupole, strength of which depends on the beam current. If a local bump of closed orbit has been created at the impedance location, then the orbit deviation occurs while varying the beam current. The local impedance can be evaluated using the orbit deviation measured. The results of the measurements and numerical calculations are presented and compared
Keywords :
accelerator cavities; accelerator magnets; electromagnets; electron accelerators; high energy physics instrumentation computing; linear colliders; particle beam diagnostics; particle beam stability; storage rings; wigglers; GdfidL code; HOM; VEPP-4M collider; accelerator cavities; beam current; ceramic inserts; closed orbit deviation; defocusing quadrupole; impedance location; localized impedance; transverse coupling impedance; vacuum chamber nonuniformity; vertical electrostatic separators; Ceramics; Computational modeling; Current measurement; Distortion measurement; Electrostatic measurements; Extraterrestrial measurements; Frequency measurement; Impedance measurement; Particle measurements; Phase measurement;
Conference_Titel :
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001
Conference_Location :
Chicago, IL
Print_ISBN :
0-7803-7191-7
DOI :
10.1109/PAC.2001.987196
