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At the Advanced Photon Source, they use two accelerators before injecting the electrons into the large storage ring. Is the addition of particles to the storage ring done in "batches" (however small/short they may be), or continuously?

By a "batch", I'm thinking where the LINAC would throw however many electrons into the booster ring, which would then accelerate them all together, then dump them all into the storage ring when they're at the appropriate energy.

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up vote 3 down vote accepted

That rather depends on the accelerator and the intended purpose of the beam.

But to choose one particular example the main electron accelerator at Jefferson Lab is the Continuous Electron Beam Accelerator Facility (CEBAF) which (duh!) functions in a continuous fashion (thought the electrons still comes in "bunches" because at any given time a RF klystron is only adding energy to particles found in part of it's length. The bunch spacing is ~2 ns in each of the three experimental halls and can be clearly reconstructed in some experiments.

That said, the ability of CEBAF to recirculate electrons in a continuous mode like that is a very special feature of the machine (which to my knowledge is not duplicated anywhere else at this time). Other than that, linear machines and synchrotrons can run in continuous mode, but accelerator rings machines must fill-n-spill.

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here is the series of accelerators feeding the LHC with pulses: espace.cern.ch/acc-tec-sector/default.aspx –  anna v Aug 6 '11 at 4:59
    
"fill-n-spill"; is that the technical term? :P –  Nick T Aug 6 '11 at 15:46
    
@Nick: It was meant to be descriptive, though I may have heard it from an accelerator guy... Certainly the Tevartron's beam delivery cycle in fixed target mode is described as having a "filling" period, and the beam is sent to the halls in a "spill". –  dmckee Aug 6 '11 at 16:06
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