Six such cavities will be used for each ring, their prime purpose being to accelerate each bunch of protons injected into the ring from its injection orbit to its final 'stacked' orbit. It is essential that the operation of the cavity should not be influenced by the presence of the beam (beam loading) and a feed-back coupled amplifier is being developed to provide the necessary low source impedence. Major problems remaining to be overcome are those of stability and control of the radiofrequency voltage.
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