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Title: Simulation of 3Qx Resonance Driving Term Measurement with AC Dipole Excitation

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) Relativistic Heavy Ion Collider
Sponsoring Org.:
USDOE SC OFFICE OF SCIENCE (SC)
OSTI Identifier:
1061856
Report Number(s):
BNL-99415-2013-IR
KB0202011
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43; relativistic heavy ion collider

Citation Formats

Luo Y., Bai, M., Bengtsson, J., Fischer, W., and Trbojevic, D. Simulation of 3Qx Resonance Driving Term Measurement with AC Dipole Excitation. United States: N. p., 2007. Web. doi:10.2172/1061856.
Luo Y., Bai, M., Bengtsson, J., Fischer, W., & Trbojevic, D. Simulation of 3Qx Resonance Driving Term Measurement with AC Dipole Excitation. United States. doi:10.2172/1061856.
Luo Y., Bai, M., Bengtsson, J., Fischer, W., and Trbojevic, D. Mon . "Simulation of 3Qx Resonance Driving Term Measurement with AC Dipole Excitation". United States. doi:10.2172/1061856. https://www.osti.gov/servlets/purl/1061856.
@article{osti_1061856,
title = {Simulation of 3Qx Resonance Driving Term Measurement with AC Dipole Excitation},
author = {Luo Y. and Bai, M. and Bengtsson, J. and Fischer, W. and Trbojevic, D.},
abstractNote = {},
doi = {10.2172/1061856},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Technical Report:

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  • Resonance driving terms for linear coupled betatron motion in a synchrotron ring can be determined from corresponding spectral lines of an excited coherent beam motion. An AC dipole is one of instruments to excite such a motion. When a coherent motion is excited with an AC dipole, measured Courant-Snyder parameters and betatron phase advance have apparent modulations, as if there is an additional quadrupole field at the location of the AC dipole. Hence, measurements of these parameters using the AC dipole require a proper interpretation of observed quantities. The situation is similar in measurements of resonance driving terms using themore » AC dipole. In this note, we derive an expression of coupled betatron motion excited with two AC dipoles in presence of skew quadrupole fields, discuss an impact of this quadrupole like effect of the AC dipole on a measurement of coupling resonance driving terms, and present an analytical method to determine the coupling resonance driving terms from quantities observed using the AC dipole.« less
  • Depolarization from an intrinsic spin resonance can be avoided by adiabatically exciting a coherent betatron oscillation. Sustained coherent transverse beam oscillations have been achieved in the AGS using a high frequency AC driven dipole magnet. The amplitude of the oscillations using the present system has been as large as 2.6 times the rms beam size, and the oscillations were held at this level for over 1,000 revolutions. By adiabatically increasing and decreasing the dipole field amplitude during this procedure, the transverse emittance of the beam was left unaffected. To set the scale, had an oscillation of that amplitude been leftmore » to oscillate freely, the beam emittance would have increased by a factor of 7 after filamentation. This result provides encouragement that this technique can be used to induce spin flip of polarized proton beams in synchrotrons when crossing strong intrinsic depolarizing resonances during acceleration. Another application of this device in a polarized beams storage ring would be the reversal of the polarized beams storage ring would be the reversal of the polarization direction of the beam. By slowly sweeping the frequency of the modulated dipole field through the spin precession frequency of the storage ring, an adiabatic spin flip can be induced, thus reversing the polarization direction of each individual particle in the storage ring without increasing the beam emittance. This can be useful for reducing systematic errors in polarized beam experiments.« less
  • The SSC collider is designed to have circumference of 87 km. The superconducting magnets along the collider ring are grouped into ten sectors. Each sector, a string of average length of 8.7 km,m is powered by one power source located near the center of the sector. Because of the alternating-current (ac) electrical characteristics of the magnets, the power supply ripple currents and transients form a time and space distribution in the magnet string which affects particle motions. Additionally, since the power supply load is a magnet string, the current regulation loop design is highly dependent upon the ac electrical characteristicsmore » of the magnets. A means is needed to accurately determine the ac electrical characteristics of the superconducting magnets. The ac characteristics of magnets will be used to predict the ripple distribution of the long string of superconducting magnets. Magnet ac characteristics can also provide necessary information for the regulation loop design. This paper presents a method for measuring the ac characteristics of superconducting magnets. Two collider dipole magnets, one superconducting and one at room temperature, were tested at Brookhaven National Lab.« less
  • The SSC collider is designed to have circumference of 87 km. The superconducting magnets along the collider ring are grouped into ten sectors. Each sector, a string of average length of 8.7 km,m is powered by one power source located near the center of the sector. Because of the alternating-current (ac) electrical characteristics of the magnets, the power supply ripple currents and transients form a time and space distribution in the magnet string which affects particle motions. Additionally, since the power supply load is a magnet string, the current regulation loop design is highly dependent upon the ac electrical characteristicsmore » of the magnets. A means is needed to accurately determine the ac electrical characteristics of the superconducting magnets. The ac characteristics of magnets will be used to predict the ripple distribution of the long string of superconducting magnets. Magnet ac characteristics can also provide necessary information for the regulation loop design. This paper presents a method for measuring the ac characteristics of superconducting magnets. Two collider dipole magnets, one superconducting and one at room temperature, were tested at Brookhaven National Lab.« less