Comparative study of medium damped and detuned linear accelerator structures

Conference · Wed Aug 22 04:00:00 EDT 2001

OSTI ID:784604

Ostiguy, Jean-Francois ^[1]

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1. Fermilab

Long range wakefields are a serious concern for a future linear collider based on room temperature accelerating structures. They can be suppressed either by detuning and or local damping or with some combination of both strategies. Detuning relies on precisely phasing the contributions of the dipole modes excited by the passage of a single bunch. This is accomplished by controlling individual mode frequencies, a process which dictates individual cell dimensional tolerances. Each mode must be excited with the correct strength; this in turn, determines cell-to-cell alignment tolerances. In contrast, in a locally damped structure, the modes are attenuated at the cell level. Clearly, mode frequencies and relative excitation become less critical in that context; mechanical fabrication tolerances can be relaxed. While local damping is ideal from the stand-point of long range wakefield suppression, this comes at the cost of reducing the shunt impedance and possibly unacceptable localized heating. Recently, the Medium Damped Structure (MDS), a compromise between detuning and local damping, has generated some interest. In this paper, we compare a hypothetical MDS to the NLC Rounded Damped Detuned Structure (RDDS) and investigate possible advantages from the standpoint fabrication tolerances and their relation to beam stability and emittance preservation.

• Research Organization: Fermi National Accelerator Lab., Batavia, IL (US)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC02-76CH03000
• OSTI ID: 784604
• Report Number(s): FERMILAB-Conf-01/183
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ALIGNMENT
BEAM DYNAMICS
DAMPING
EXCITATION
FREQUENCY CONTROL
LINEAR ACCELERATORS
LINEAR COLLIDERS
PERFORMANCE
TUNING