Chromaticity Measurements Using Phase Modulated RF and Vector Signal Analyzers
Abstract
Chromaticity measurements are usually done by changing the energy of the beam by a known amount and measuring the change in betatron tune with a spectrum analyzer. The energy change is done by adjusting the RF frequency. The change in RF frequency is made large enough so that the change in betatron tune can be seen. If synchrotron motion is present in the beam, then measuring the change in betatron tune can be difficult. This note will outline a method to measure the change in betatron tune by phase-modulating the RF and measuring the phase modulated betatron spectrum Extremely small resolution bandwidths are available on modern vector signal analyzers. A small resolution bandwidth is equivalent to measuring the chromaticity many times and averaging the results. This would permit much smaller shifts in betatron tunes to be measured. The phase-modulated signal consists of sidebands whose amplitudes are given by Bessel functions. The complication of the Bessel functions can be removed if the vector signal analyzer is capable of phase demodulation. The sign of the chromaticity can be determined by observing the modulation spectrum at both betatron sidebands.
- Authors:
- Publication Date:
- Research Org.:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 984578
- Report Number(s):
- FERMILAB-PBAR-NOTE-656
TRN: US1005993
- DOE Contract Number:
- AC02-07CH11359
- Resource Type:
- Technical Report
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 43 PARTICLE ACCELERATORS; AMPLITUDES; BESSEL FUNCTIONS; BETATRONS; MODULATION; RESOLUTION; SYNCHROTRONS; VECTORS; Accelerators
Citation Formats
McGinnis, Dave, and /Fermilab. Chromaticity Measurements Using Phase Modulated RF and Vector Signal Analyzers. United States: N. p., 2001.
Web. doi:10.2172/984578.
McGinnis, Dave, & /Fermilab. Chromaticity Measurements Using Phase Modulated RF and Vector Signal Analyzers. United States. doi:10.2172/984578.
McGinnis, Dave, and /Fermilab. Fri .
"Chromaticity Measurements Using Phase Modulated RF and Vector Signal Analyzers". United States.
doi:10.2172/984578. https://www.osti.gov/servlets/purl/984578.
@article{osti_984578,
title = {Chromaticity Measurements Using Phase Modulated RF and Vector Signal Analyzers},
author = {McGinnis, Dave and /Fermilab},
abstractNote = {Chromaticity measurements are usually done by changing the energy of the beam by a known amount and measuring the change in betatron tune with a spectrum analyzer. The energy change is done by adjusting the RF frequency. The change in RF frequency is made large enough so that the change in betatron tune can be seen. If synchrotron motion is present in the beam, then measuring the change in betatron tune can be difficult. This note will outline a method to measure the change in betatron tune by phase-modulating the RF and measuring the phase modulated betatron spectrum Extremely small resolution bandwidths are available on modern vector signal analyzers. A small resolution bandwidth is equivalent to measuring the chromaticity many times and averaging the results. This would permit much smaller shifts in betatron tunes to be measured. The phase-modulated signal consists of sidebands whose amplitudes are given by Bessel functions. The complication of the Bessel functions can be removed if the vector signal analyzer is capable of phase demodulation. The sign of the chromaticity can be determined by observing the modulation spectrum at both betatron sidebands.},
doi = {10.2172/984578},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Feb 16 00:00:00 EST 2001},
month = {Fri Feb 16 00:00:00 EST 2001}
}
-
Longitudinal Tracking with Phase and Amplitude Modulated RF
Synchrotron motion was induced by phase shifting the rf of the Indiana University Cyclotron Facility (IUCF) cooler-synchrotron. The resulting coherent-bunch motion was tracked in longitudinal phase space for as many as 700,000 turns, or for over 350 synchrotron oscillations. Results of recent experimental studies of longitudinal motion in which the rf phase and amplitude were harmonically modulated are also presented. Comparisons of experimental data with numerical simulations, assuming independent particle motion, are made. Observed multiparticle effects are also discussed. -
Improved oscillator phase locking using a modulated electron beam in a gyrotron. Interim report
A new method of microwave oscillator phase locking exploiting the extended nature of the gyrokylstron configuration is accomplished by modulating the electron beam before it reaches the cavity oscillator. The amount of power required to phase lock a gyroton is decreased by more than an order of magnitude from that predicted by Alder's theory. In addition, oscillator priming is observed at drive powers below all other systems tested to date. These new methods provide the coherence required of RF sources for linear accelerators and may enhance gyrotron performance for fusion heating.