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| PT12 |
Beam Phase Measurements in the AGOR Cyclotron
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193 |
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- S. Brandenburg, H.W. Nijboer, W.K. van Asselt
KVI, Kernfysisch Versneller Instituut, Groningen, The Netherlands
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Beamphase measurement to optimize the isochronism is an essential part of
the diagnostics in multi-particle, multi-energy cyclotrons. In the AGOR
cyclotron an array of 13 nondestructive beamphase pick-ups is installed.
To reduce the large disturbances from the RF-system the measurements are
traditionally performed at the 2nd harmonic of the RF-frequency. To
further improve the sensitivity intensity modulation of the beam has been
introduced. This creates side-bands in the Fourier spectrum, that are
completely free of interference from the RF-system. These side-bands
contain information on both the beamphase with respect to the
accelerating voltage and the number of revolutions up to the radius of
the measurement. A specific case is intensity modulation at the orbital
frequency, where the side-bands contain only information on the
beamphase. Measurements with the different methods will be presented,
demonstrating that the intensity modulation strongly improves the
sensitivity of the measurement. Useful beamphase measurements can now be
made for beam intensities down to 10 nA.
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