| Paper |
Title |
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| MOP24 |
Using a Solid State Switch for a 60kV Bouncer to Control Energy Spread during the Beam Pulse*
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87 |
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- L. Donley, J.C. Dooling, G.E. McMichael, V. F. Stipp
ANL, Argonne, Illinois
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The beam injected into the IPNS Linac is from a column utilizing a Cockcroft-Walton voltage source. The accelerating column consists of a single high gradient gap. To lessen the likelihood of gap voltage breakdown, we pulse (“bounce”) the column voltage up during the beam pulse allowing the column DC voltage to be lower. The accelerating voltage is supplied through a 5 MΩ resistor and has only small capacitance to hold the voltage constant during the beam pulse. A capacitor is connected between the high voltage end of the column and the bouncer pulse generator. The bouncer pulse increases the column voltage to the proper level just microseconds before the beam pulse. A slope on the top of the bouncer pulse allows for correction to be added, compensating for the voltage droop that results from beam loading. The bouncer that has served this purpose in the past utilized a tube amplifier. In searching for a suitable replacement system it was decided that the system should be able to deliver a 60 kV pulse and the slope on the top of the pulse could be controlled by an RC rise. A solid state switch was purchased for this application. Switch protection and other design decisions will be discussed.
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| TUP61 |
Beam Analysis Using the IPNS Linac ESEM
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405 |
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- J.C. Dooling, F. R. Brumwell, L. Donley, G.E. McMichael, V. F. Stipp
ANL, Argonne, Illinois
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The Energy Spread and Energy Monitor (ESEM) is an on-line, non-intrusive diagnostic used to characterize the output beam from the 200 MHz, 50 MeV linac. The energy spread is determined from a 3-size, longitudinal emittance measurement and energy is derived from TOF analysis. Presently, a single particle distribution is used to yield energy and energy-spread results. Effort is on-going to allow for more realistic distributions to be included. Signals are detected on terminated 50 Ω, stripline BPMs. Each BPM is constructed with four striplines: top, bottom, left and right. Until recently, the ESEM signals were taken solely from bottom striplines in four separate BPM locations in the transport line between the linac and synchrotron. We have begun to use the top stripline data to examine, in more detail, beam position and attempt to measure beam size. The electrostatic coupling between the stripline and the beam depends on the capacitance, which in turn is inversely related to the beam-stripline separation. The electrostatic portion of fluctuations in beam motion will be nonlinear, possibly allowing one to infer beam size.
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