Chromaticity correction in circular accelerators and storage rings: Part 1, A user's guide to the HARMON programs

Technical Report · Sun Jul 01 04:00:00 EDT 1979

OSTI ID:6614566

Donald, M

In circular accelerators and storage rings it is necessary to control the linear chromaticity defined as xi/sub x,y/ = /sub x,y//delta with /sub x,y/, the linear variation of the tunes with the fractional momentum deviation, delta. In small accelerators it is usually only necessary to control this linear variation by the use of two families of sextupoles powered by two power supply circuits. With SF sextupoles and SD sextupoles, the solution for the magnetic fields of the two sextupole families is uniquely determined by the desired values of the linear chromaticities, xi/sub x,y/. With the invention of low US insertions for storage rings, problems associated with nonlinear chromaticity became apparent even in quite small SPEAR size machines, became serious in PEP and PETRA size machines and are design limits in machines the size of LEP and greater. The HARMON programs were written for the PEP generation machines and work on the principle of finding the adverse effects of a particular quadrupole-sextupole configuration and then adjusting the sextupole strengths to minimize these effects. A minimizing rather than an equation solving technique was adopted since it was found better to reduce many adverse rather than to eliminate just a few. The latter case usually resulted in strong sextupoles and hence poor performance. Although some guidance may be obtained from the program on how to arrange the families of sextupoles, no attempt is made in the program to redesign the configuration. This guidance can be achieved through studying the sensitivity of various parameters to the strengths of individual sextupoles. 13 refs.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (USA)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 6614566
• Report Number(s): SLAC-PEP-NOTE-311; ON: DE89006343
• Country of Publication: United States
• Language: English

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