Effect of a Wire on the Electromagnetic Field  in an Accelerating Cavity   in the Coaxial-Wire Method

Toyomasu, Takanori; Izawa, M.; Kamiya, Yukihide

doi:10.1143/jjap.34.340

Cited by 2 publications

(2 citation statements)

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“…15 is twice the real part of the beam coupling impedance, From this figure, the maximum value of the shunt impedance is about 450 at 1170 MHz which is 39.5 MHz higher than the simulation result of 1130.5 MHz, and 54.4 MHz higher than the result of the previous parameter measurement, 1115.6 MHz. This frequency shift is due to the 3-mm diameter wire [7], [34]. After considering a negative value of the near 1600 MHz due to calibration and gating errors, the maximum value of the shunt impedance is increased to about 470 .…”

Section: Measurementsmentioning

confidence: 99%

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Longitudinal feedback system kicker for the PLS storage ring

Kim

Kwon

Huang

et al. 2000

IEEE Trans. Nucl. Sci.

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The higher order modes (HOM's) of RF cavities at the Pohang Light Source (PLS) storage ring cause longitudinal coupled bunch mode instabilities. A longitudinal feedback system (LFS) is introduced to cure these instabilities. As a key component of the LFS, there is a single-ridged waveguide-overloaded cavity for a longitudinal bunch-by-bunch LFS kicker. Since the RF frequency is 500 MHz, the bandwidth of this kicker should be wider than 250 MHz to damp any coupled bunch mode. Also, a higher shunt impedance of the kicker is selected to use a lower power amplifier. One aluminum kicker is fabricated, and the bandwidth, HOM's, and the shunt impedance of the kicker are measured with a network analyzer. This kicker has several different features from the LFS kicker for DA8NE. First of all, there are four input/output ports to obtain a wider bandwidth. Second, there is a nose cone to obtain a higher shunt impedance. Third, the symmetric frequency response of the shunt impedance around the central frequency is provided. Finally, low beam coupling power (4 W per port at 400 mA) is obtained. According to the simulation result by the high frequency structure simulator (HFSS) code, we obtained the high shunt impedance of 621.3 (transit time factor considered value) and the wide bandwidth of 255 MHz. These are compared with the measured result.Index Terms-Coupled bunch mode instability, HOM, longitudinal feedback system kicker, wake fields.

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Section: Measurementsmentioning

confidence: 99%

“…There are some differences between measured values and HFSS simulation results as described in Section IV. But, if the diameter of the 3 mm wire is reduced, the maximum shunt impedance will be increased further, and the central frequency shift will be decreased [7], [34].…”

Section: Measurementsmentioning

confidence: 99%