456
F. Bordry et al.
Septum magnet
Kicker magnet
(installed in
circulating beam)
Circulating beam
Quad
(defocusing in
injection plane)
Homogeneous
field
Field free region
Quad
(focusing in
injection plane)
time
kicker
field
intensity
injected
beam
‘boxcar’ stacking
circulating
beam
Fig. 8.66 Fast single-turn injection in one plane
are operated with very high fields and must also cope with the heat load from the
impinging beam. To reduce the particle losses septa (coils, or foils/wires in case of
electrostatic septa) must be as thin as possible; nevertheless, the characteristics of
the beam processes involved mean that septa are usually among the most radioactive
parts of an accelerator, together with collimators and dumps. This has to be taken
into account during the design, for example, it must be possible to quickly assemble
and release electrical, water and vacuum connections.
The rise time of the field produced by the kicker magnets must be very short
(ranging from several tens of μs down to several ns), while the requirements for
low ripple and good reproducibility of the flat-top amplitude are stringent (at least
considering the pulse-type excitation). Redundancy can also be an important design
criterion: if one of the devices fails the remaining devices should be sufficient,
in combination with special protection elements, to handle the beam safely. For
single-turn injection or extraction there is only one action on the beam and the
timing needs to be precisely set up; although it may be feasible to compensate for
small, non-ideal, deflection of the first and last bunches of a train [164], significant
online corrections are not possible. Applications are often safety critical (beam abort
systems) and imminent failures must be recognized in real time.
8.7.1 Fast Pulsed Systems (Kickers)
Apart from their use for injection and extraction purposes specific kickers are also
used to excite the beam, for instance to measure the tune or probe the machine
aperture. Kicker magnet yokes are frequently made out of NiZn ferrite because of its
relatively high resistivity and magnetic permeability: with the NiZn ferrite field rise
F. Bordry et al.
Septum magnet
Kicker magnet
(installed in
circulating beam)
Circulating beam
Quad
(defocusing in
injection plane)
Homogeneous
field
Field free region
Quad
(focusing in
injection plane)
time
kicker
field
intensity
injected
beam
‘boxcar’ stacking
circulating
beam
Fig. 8.66 Fast single-turn injection in one plane
are operated with very high fields and must also cope with the heat load from the
impinging beam. To reduce the particle losses septa (coils, or foils/wires in case of
electrostatic septa) must be as thin as possible; nevertheless, the characteristics of
the beam processes involved mean that septa are usually among the most radioactive
parts of an accelerator, together with collimators and dumps. This has to be taken
into account during the design, for example, it must be possible to quickly assemble
and release electrical, water and vacuum connections.
The rise time of the field produced by the kicker magnets must be very short
(ranging from several tens of μs down to several ns), while the requirements for
low ripple and good reproducibility of the flat-top amplitude are stringent (at least
considering the pulse-type excitation). Redundancy can also be an important design
criterion: if one of the devices fails the remaining devices should be sufficient,
in combination with special protection elements, to handle the beam safely. For
single-turn injection or extraction there is only one action on the beam and the
timing needs to be precisely set up; although it may be feasible to compensate for
small, non-ideal, deflection of the first and last bunches of a train [164], significant
online corrections are not possible. Applications are often safety critical (beam abort
systems) and imminent failures must be recognized in real time.
8.7.1 Fast Pulsed Systems (Kickers)
Apart from their use for injection and extraction purposes specific kickers are also
used to excite the beam, for instance to measure the tune or probe the machine
aperture. Kicker magnet yokes are frequently made out of NiZn ferrite because of its
relatively high resistivity and magnetic permeability: with the NiZn ferrite field rise