The coupled dipole modes of the NLC accelerator structure

Conference · Sun Mar 01 04:00:00 EST 1992

OSTI ID:10138902

Bane, K L.F.; Gluckstern, R; Holtkamp, N

The proposed accelerator cavity of the Next Linear Collider (NLC) is a disk-loaded structure composed of 200 cells, operating at 11.42 GHz. The proposed mode of operation is to accelerate bunches in trains of 10, with a bunch spacing of 42 cm. One problem is that one bunch in a train can excite transverse wakefields in the accelerator cavity which, in turn, can deflect following bunches and result in emittance growth. A method of curing this problem is to detune the transverse modes of the cavity. Beam dynamics simulations for the NLC have shown that by keeping the transverse wakefield at the positions of the nine trailing bunches at or below 1 MW/nC/m{sup 2} we can void emittance growth. Earlier, approximate calculations of the wakefields, which did not include the cell-to-cell coupling of the modes, have shown that by the proper Gaussian detuning the above level of cancellation can be achieved. A specific goal of this report is to see if this conclusion still holds when coupling is included in the calculation. Note that in this paper we focus on the modes belonging to the first dipole passband, which are the most important. A special feature of these modes in the detuned NLC cavity is that the cell-to-cell coupling changes sign somewhere in the middle of the structure.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 10138902
• Report Number(s): SLAC-PUB--5766; CONF-920315--12; ON: DE92011584
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200
BEAM BUNCHING
BEAM DYNAMICS
BEAM DYNAMICS, FIELD CALCULATIONS, AND ION OPTICS
BEAM EMITTANCE
BEAM OPTICS
CAVITY RESONATORS
EQUIVALENT CIRCUITS
LINEAR COLLIDERS
MAGNETIC DIPOLES
TUNING