| Magnet Unit(s) | 2022,3122 |
|---|---|
| Typical BDES | 20.358 kG |
| Typical Current | 80 A |
| Typical PS Voltage | 60 V |
| Nominal Beta X | 23 m |
| Nominal Eta X | 0.4 m |
| Nominal Beta Y | 7.5 m |
| Nominal Eta Y | 0.0 m |
QFW9 is one of the family of quadrupole magnets used to generate the optics appropriate for the wiggler chicane in straight 6.
LER straight 6 is not straight. Rather it is taylored for placement of wiggler magnets at the center of a horizontal chicane bypass. The purpose of the wigglers is to adjust the horizontal beam emittance and radiation damping time of the LER beam. Presently the wiggler magnets in straight 6 are not powered.
The chicane bypass is achieved using four ordinary LER dipole bending magnets powered in series with the arc dipoles. ~20m into the straight a "BB+" dipole bends the beam inward. Another ~20 m in another dipole "BB-" bends the beam back parallel to the straight's axis, with the trajectory now offset ~1 m hortizontally from the normal line of the straight. The ~5 m surrounding the straight midpoint is then occupied by wiggler magnets. Another "BB-", "BB+" pair symetric about the straight midpoint with the first set then complete the chicane.
Twenty four quadrupole magnets driven by ten power supplies (QDW, QDW1-QFW9) are employed within this chicane to adjust the optics at the wigglers. The objective is to maintain a large uniform horzontal dispersion function within the wigglers, with a long (i.e. not steeply divergent) waist within the wigglers.
The wiggler straight's quadrupoles are powered symetrically about the straight's midpoint. Six of these quadrupole magnets (QFW3, QDW2, and QFW1 on both sides) are within the inner straight part of the chicane. Ten quadrupole magnets (powered by QFW4, QDW5, and QFW6) are within the BB- and BB+ dipoles, and eight quadrupole magnets (powered by QDW, QFW9, QDW8, and QFW7) are between the BB- dipoles and the outboard arcs.