Q1 and Q2 magnets design and their construction

The mechanical designs of the Q1 and Q2 magnets are shown in Fig. 13 and 14. The Q1, Q2 were designed so that their upper and lower yokes are separated to allow photon and deflected electron beam escape the gap of Q1 and Q2. They are mechanically supported by spacers between the upper and lower poles and the widths of Q1 and Q2 are minimized as shown in the figures. By this way, Q1 can be installed very close to the splitter magnet without bumping to the Enge spectrometer and the larger solid angle of the HKS is realized.

**表 9:** Q1 and Q2 parameters
Item	Q1	Q2
Bore radius (mm)	120	145
Pole length (mm)	840	600
Max. Ampere turns (A turns)	224000	144000
Number of turns	256	320
Conductor size	8 $\times$ 8 ( $\phi$ 6 hole)	13.5 $\times$ 11.5 ( $\phi$ 6.3 hole)
Coil Winding	Double Pancake Winding	Solenoid Winding
Field Gradient (T/m)	6.6	4.2
Max. Current (A)	875	450
Resistance (m $\Omega$ )	181 (@55 $^\circ$ C)	119 (@45 $^\circ$ C)
Cooling Water Flow rate (l/m)	49.6	17.3
Pressure drop (MPa)	0.36	0.38
Number of Coolant circuits	16	8
Total Magnet Weight (ton)	8.2	10.5
metric ton.

The required integral field gradients for Q1 and Q2 are respectively -5.20 (T/m) $\cdot$ m and 2.47 (T/m) $\cdot$ m as shown in section 3.2. A TOSCA 3D magnetic field calculation was performed (figure 15) and it was confirmed that the required integral field gradients are achieved before the saturation of iron starts for both Q1 and Q2.