2.5.3 Electromagnet Wigglers
Wigglers generally consist of a series of ~10–20 powerful dipole bend magnets
arranged at a constant spacing. Many wigglers use electromagnets based on coils and
pole pieces (Fig. 2.16). Weaker magnets are placed at each end, so that the particle
beam emerges from the device in the same direction that it entered.
It turns out that electromagnets are great for producing high fields with long
periods. However, when a shorter period is desired, the current density required for
the magnet coils becomes unreasonably large, and a different technology is required
[30]. For this reason, a new kind of insertion device based on permanent magnets
was invented.
Fig. 2.14 Top left: ALS superbend modification of lattice. A pair of quadrupole magnets is also
added, since the bend magnet being replaced had some focusing properties. Bottom left: the device
before installation. Right: lowering the superbend into the ALS ring
Fig. 2.15 Left: particle trajectory in the SPring-8 Wavelength Shifter. Right: the SPring-8 device
before installation in the ring
2.5 Insertion Device Hardware
29
Wigglers generally consist of a series of ~10–20 powerful dipole bend magnets
arranged at a constant spacing. Many wigglers use electromagnets based on coils and
pole pieces (Fig. 2.16). Weaker magnets are placed at each end, so that the particle
beam emerges from the device in the same direction that it entered.
It turns out that electromagnets are great for producing high fields with long
periods. However, when a shorter period is desired, the current density required for
the magnet coils becomes unreasonably large, and a different technology is required
[30]. For this reason, a new kind of insertion device based on permanent magnets
was invented.
Fig. 2.14 Top left: ALS superbend modification of lattice. A pair of quadrupole magnets is also
added, since the bend magnet being replaced had some focusing properties. Bottom left: the device
before installation. Right: lowering the superbend into the ALS ring
Fig. 2.15 Left: particle trajectory in the SPring-8 Wavelength Shifter. Right: the SPring-8 device
before installation in the ring
2.5 Insertion Device Hardware
29