Operational experience with SLC damping ring kicker magnets

Mattison, T.; Cassel, R.; Donaldson, A.; Gross, Gil J.; Harvey, A.

doi:10.1109/pac.1991.164956

Cited by 7 publications

(3 citation statements)

References 2 publications

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“…As a major change from the high-voltage-gradient design of the Fermi-style kicker, SLAC is developing an epoxy-resin insulated design of kicker with a much lower gradient [3]. In addition to reducing the problem of corona breakdown, the new design is expected to be much less susceptible to radiation damage.…”

Section: Future Directionsmentioning

confidence: 99%

Manufacture of fast-pulsed magnets for the SLC damping rings

et al. 1992

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Section: Future Directionsmentioning

confidence: 99%

Manufacture of fast-pulsed magnets for the SLC damping rings

et al. 1992

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“…There have been two generations of SLC kicker magnets [1,2]. The first generation of SLC kicker magnets suffered from high voltage breakdown through the joints between the ferrite tiles used for both flux return and capacitor dielectric.…”

Section: Old and New Magnet Designsmentioning

confidence: 99%

“…Voltages of up to 40 kV are required. There are substantial beam losses near the kicker magnets, with localized radiation levels of order 10 8 rads.There have been two generations of SLC kicker magnets [1,2]. The first generation of SLC kicker magnets suffered from high voltage breakdown through the joints between the ferrite tiles used for both flux return and capacitor dielectric.…”

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Fast and reliable kicker magnets for the SLC damping rings

Mattison

Cassel

Donaldson

et al.

Proceedings Particle Accelerator Conference

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The design, construction, and operation of a kicker magnet with superior electromagnetic performance and greatly improved radiation tolerance is described. A short flux return of high mu ferrite improves the field strength and linearity with current, and novel metallic fieldconfining structures minimize the inductance. An 8-cell structure with capacitance integrated into each cell makes the magnet a nearly perfect transmission line. The capacitor dielectric is 1 cm thick alumina-loaded epoxy, processed to eliminate air voids, and cast in a multiple step procedure developed to circumvent epoxy shrinkage. The magnet operates with pulses of up to 40 kV and 3.2 kA at 120 Hz, with magnet transit times of less than 35 nsec and field rise and fall times of less than 60 nsec. I. OLD AND NEW MAGNET DESIGNSThe Stanford Linear Collider (SLC) uses two 1.2 GeV damping rings to reduce the emittance of the e + and ebunches before acceleration in the main linac. Each damping ring requires an injection and extraction kicker magnet with rise and fall times of less than 60 nsec. The thyratron pulsers have rise/fall times of at best 25 nsec, so the magnet contribution must not exceed 35 nsec. The ekickers must inject or extract both bunches on a single pulse, requiring a 60 nsec flat top and two e -extraction kicks must be different by less than 10 -3 . These requirements are best met by a matched and terminated transmission line magnet. The kickers are outside of 21 mm diameter ceramic beam pipes, and the space allocated is less than 50 cm long. Voltages of up to 40 kV are required. There are substantial beam losses near the kicker magnets, with localized radiation levels of order 10 8 rads.There have been two generations of SLC kicker magnets [1,2]. The first generation of SLC kicker magnets suffered from high voltage breakdown through the joints between the ferrite tiles used for both flux return and capacitor dielectric. They also had poor pulse quality, behaving more like LC elements than transmission lines, and were not suitable for extracting two e -bunches on a single pulse. In the second generation of SLC kicker *Work supported by the US Department of Energy Contract DE-AC03-76SF00515. magnets, the capacitance was provided by a 2 mm thick layer of RTV silicone rubber between the center conductor and grounded aluminum segments containing large slotted ferrite flux return cores. The RTV also became brittle upon exposure to radiation, then cracked when thermally cycled. In some locations the lifetime averaged as low as 10 days. There was substantial stray inductance due to the distance between the center conductor and the beam pipe. A ferrite advertised as low-mu was used, for low inductance (but low kick per ampere) but the mu at operating current levels was substantially higher, leading to a higher inductance and mismatch. The second generation could be used for extracting two e -bunches on a single pulse, but only by shaping the current pulse to compensate for the mismatch of the magnet.A new kicker magnet has been...

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