LARP LARP Document 998-v1

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STABILIZING EFFECT OF A DOUBLE-HARMONIC RF SYSTEM IN THE CERN PS

Document #:
LARP-doc-998-v1
Document type:
Proceeding
Submitted by:
Chandrashekhara Bhat
Updated by:
Chandrashekhara Bhat
Document Created:
12 Oct 2009, 14:28
Contents Revised:
12 Oct 2009, 14:28
DB Info Revised:
12 Oct 2009, 14:28
Viewable by:
  • Public document
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Abstract:
Motivated by the discussions on scenarios for LHC upgrades,
beam studies on the stability of flat bunches in a
double-harmonic RF system have been conducted in the
CERN Proton Synchrotron (PS). Injecting nearly nominal
LHC beam intensity per cycle, 18 bunches are accelerated
on harmonic h = 21 to 26GeV with the 10MHz RF system.
On the flat-top, all bunches are then transformed to
flat bunches by adiabatically adding RF voltage at h = 42
from a 20MHz cavity in anti-phase to the h = 21 system.
The voltage ratio V (h42)/V (h21) of about 0.5 was set according
to simulations. For the next 140 ms, longitudinal
profiles show stable bunches in the double-harmonic RF
bucket until extraction. Without the second harmonic component,
coupled-bunch oscillations are observed. The flatness
of the bunches along the batch is analyzed as a measure
of the relative phase error between the RF systems due
to beam loading. The results of beamdynamics simulations
and their comparison with the measured data are presented.
Files in Document:
  • pdf (FR5RFP058.pdf, 621.7 kB)
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