Technical Design Report Super Fragment Separator
Technical Design Report Super Fragment Separator
Technical Design Report Super Fragment Separator
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DRAFT<br />
The magnets will be operated in DC mode but it must be guaranteed that all magnets in a multiplet<br />
can be ramped up from gmin to gmax and ramped down from gmax to gmin within 12 minutes. This is<br />
necessary in order to guarantee a frequent changing of the magnet setting due to experimental<br />
requirements. The maximum current of one magnet must not exceed 300 ampere. All magnets are<br />
individually powered. The breakdown voltage, Vbd, against ground of all magnets, sensors and<br />
connections must be:<br />
V > 2 ⋅V<br />
+ V<br />
bd<br />
where Vqm is the maximum quench voltage to ground and Vsm = 500 V is a safety margin.<br />
Magnetic design<br />
The 2D/3D magnetic design for the quadrupoles was performed using the code Opera-2D/3D [15].<br />
Figure 2.4.45 shows the cross section of a standard quadrupole magnet for the <strong>Super</strong>-FRS. The<br />
pole tip radius of 250 mm was chosen in order to provide sufficient space for the beam pipe (190<br />
mm inner diameter + 10 mm expected wall thickness), for the cryostat (expected thickness of 30<br />
mm), and for the octupole correction coils (about 5-15 mm), which are needed to correct the<br />
ion-optical 3 rd -order image aberrations. For simplicity of winding the main coil is designed as a<br />
race track coil with a cross section of (55 × 50) mm 2 .<br />
Figure 2.4.45: Cross section (1/4 part) of the standard superferric quadrupole magnet for the <strong>Super</strong>-FRS<br />
including octupole correction coils.<br />
Figure 2.4.46 shows the dependencies of the average field gradient along the elliptical aperture for<br />
a quadrupole magnet. It presents the field quality distributions for the medium/high field gradients<br />
of 5.6, 7.7 and 8.7 T/m. The field gradient deviation is well inside the specification of ±8·10 -4<br />
relative units. For the highest field gradients of 10 T/m, however, the 6 th harmonics increases<br />
exponentially such that field quality distribution reduces to few ‰ (see Figure 2.4.47). These errors<br />
can be corrected by additional 12-pole correction coils also embedded into the quadrupole. The<br />
present layout of the quadrupole magnet leaves enough space to include these correction coils if<br />
necessary which will allow to reduce the field gradient deviation to ≈ ±4·10 -4 even for the highest<br />
gradient of 10 T/m.<br />
qm<br />
sm<br />
46