| Magnet Unit(s) | PR02:9012 |
|---|---|
| Typical BDES | -35.026 kG |
| Typical Current | 120 A |
| Typical PS Voltage | 20 V |
| Nominal Beta X | 16 m |
| Nominal Eta X | 0.0 m |
| Nominal Beta Y | 26 m |
| Nominal Eta Y | 0.0 m |
QDS0R is one of a family of seven individually powered quadrupole magnets (QDS3R, QFS3R, QDS2R, QFS2R, QDS1R, QFS1R, and QDS0R) at the beginning of arc 3. There is a comparable set at the end of arc 3, and at the beginning and end of arc 1.
In general the HER arcs have QFs and QDs each powered in series for the whole ring except for the seven quadrupole magnets at the beginning and end of the arc. For a general HER arc, these first/last seven are used to cancel the dispersion going into the adjacent straights, and to generate a dispersion mismatch in the arc which controls (increases) the horizontal beam emittance. The HER arcs not adjacent to IR2 (generally) have these "dispersion suppressor" quads powered together by one power supply for each family member (eg QFS2 appears eight times in the four non-IR2 adjacent arcs such that eight QFS2 magnets share one power supply called QFS2E).
Technically speaking the QDS0R magnet is not actually in the arc, rather it is before the first arc 3 dipole 9012. It is proper however to include the QDS0 family of magnets (technically in the straight) as part of the arc dispersion supression scheme.
Arcs 1 and 3 (being adjacent to IR2) have this "dispersion suppressor" scheme done with individual power supplies for each magnet (except the QDS3 on the outward half arcs which are in series with the rest of the ring's QDs) to allow further tunability of the dispersion and beta functions adjacent to the collision straight at IR2.