Beam Energy Loss to Parasitic Modes in Spear II

Allen, M. A.; Paterson, J. M.; Rees, J.; Wilson, Perry B.

doi:10.1109/tns.1975.4328005

Cited by 17 publications

(5 citation statements)

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“…The most precise, general purpose instrument to measure the phase of RF signals is the vector voltmeter. It is traditionally the instrument of choice for synchronous phase shift measurements [4,5,6]. However, as we found in our experiments, we could not measure the synchronous phase shift reliably with a Hewlett-Packard (HP) 8508A vector voltmeter.…”

Section: Traditional Way To Measure the Synchronous Phase Shift mentioning

confidence: 61%

New apparatus for precise synchronous phase shift measurements in storage rings

Podobedov

Siemann

1998

Phys. Rev. ST Accel. Beams

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Measuring a synchronous phase shift as a function of beam current is commonly done in accelerator physics to estimate the longitudinal impedance of a storage ring vacuum chamber. This measurement is normally done with RF techniques that do not have enough accuracy to detect small phase shifts typical to the newer storage rings. In this paper we report results from a new method for precise measurement of a synchronous phase shift. Our method involves downmixing from the RF frequency to a kHz range and then using an audio DSP lock-in amplifier for the actual phase detection. This paper describes the idea and the advantages of a new method as well as its practical implementation in the apparatus we build for precise synchronous phase measurements in the Stanford Linear Collider damping rings. The results of those measurements are also presented. [S1098-4402(98)00020-2]

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Section: Traditional Way To Measure the Synchronous Phase Shift mentioning

confidence: 61%

New apparatus for precise synchronous phase shift measurements in storage rings

Podobedov

Siemann

1998

Phys. Rev. ST Accel. Beams

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“…Beambased impedance measurement techniques exist as well. The integrated longitudinal impedance of a circular machine can be measured via the shift in synchronous phase vs. current of a single test bunch [3,4]. By varying bunch length in such measurements one can estimate the parameters of the broad-band equivalent impedance [5,6].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Longitudinal Impedances in Storage Rings Via Multibunch Effects

Teytelman¹

2002

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In this paper we present two new techniques for frequency-resolved characterization of longitudinal impedances in storage rings. The first method is based on transient measurements of the growth rates and tune shifts of unstable coupledbunch modes. In the second approach estimates of the impedances are obtained from analysis of the steady-state synchronous phases of the bunches for uneven fill patterns. These techniques are applicable to measurement of both fundamental and higher-order mode impedances and allow characterization of shunt impedances and quality factors of the HOMs. Methods presented here are complementary to lab bench measurements of RF cavities, in that the beam based measurements directly sense the physical impedance in the installed configuration. Experimental results from ALS and BESSY-II are presented showing the use of these techniques to measure complex impedances.

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“…The variation of the synchronous phase shift as a function of gap voltage has been used to determine the energy loss to synchrotron radiation [2], and its variation as a function of beam current has been used in several machines [2][3][4][5] to determine parasitic mode losses. In most of these measurements, rf phase detection techniques are used and commercial vector voltmeters or network analyzers are often the instruments of choice.…”

Section: Introductionmentioning

confidence: 99%

Oscilloscope measurement of the synchronous phase shift in an electron storage ring

Farias

Liu

Rodrigues

et al. 2001

Phys. Rev. ST Accel. Beams

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We present a new technique to measure the synchronous phase shift in an electron storage ring. A digital sampling oscilloscope is used to observe the cavity and beam signals simultaneously, and the amplitude and relative phase are obtained from a Fourier transform of the time-domain data. This procedure gives 6 mdeg resolution and is largely insensitive to input signal amplitude variations. The measurement system was used to study the dependence of the synchronous phase shift on beam current, gap voltage, and beam energy in the Brazilian Synchrotron Light Source electron storage ring.

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Beam Energy Loss to Parasitic Modes in Spear II

Cited by 17 publications

References 0 publications

New apparatus for precise synchronous phase shift measurements in storage rings

New apparatus for precise synchronous phase shift measurements in storage rings

Characterization of Longitudinal Impedances in Storage Rings Via Multibunch Effects

Oscilloscope measurement of the synchronous phase shift in an electron storage ring

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