Accelerator Magnet Technology Division

a) Wiggler magnet for Indus-1

The magnetic lattice of the Indus-1 ring consists of 4 super periods, each having one dipole magnet with a field index of 0.5 and two doublets of quadrupoles. Each super period has a 1.3 m long straight section. A 3 Tesla wiggler was planned to put in one the straight section while other straight sections are used for beam injection (septum and pulsed kicker magnet) and one for RF cavity.

A 3 T air core wiggler magnet was designed. The magnet consists of 14 racetrack main coils. Out of these 7 coils will be laid above the mid plane and remaining 7 coils will be placed symmetrically below the mid plane. The 7 coils are divided in three coil groups. All the 14 coils will be connected in such a way so that only three power supplies can produce the desired field profile. The detail of quench analysis has been carried out. Figure 1 shows the 3-D view of the wiggler along with the 3D field variation in the coils. The 3D field distribution in the mid plane (SX plane S= Ph 250mm, X= Ph300 mm, Z=0) is shown in figure 2.

Figure 1: The 3-D view of the wiggler along with the 3D field variation in the coils.

Figure 2: The 3D field distribution in the mid plane (SX plane, S=±25 cm, X=±30 cm and Z=0).

b) Undulator magnet

Apple2 type of Undulator for Indus-2 is designed to produce circularly polarized radiation of 180 to 1000 eV. Parameters regarding to magnet design to produce radiation in the energy range of 100 eV to 1500 eV is given in table 1. A permanent magnet having six periods is designed for initial fabrication. Gap between two movable rows is taken as 1 mm.

End blocks are introduced to minimize the field integrals, which will remain within 50 G.cm for various pole gaps and phases. Attempt has been made to achieve this without using any trim coils. It needs a bit complicated end blocks design but the simulation results using TOSCA show the effectiveness of the end block to maintain field integral within tolerable range. Figure 1 shows the arrangements of magnets and the end blocks for a 6 period Undulator. 3D field variation of vertical field for zero phase, 20 mm pole gap and 72 mm period length as estimated using TOSCA is shown in fig. 2.

Table 1: Major parameters of Apple2 type Undulator

Magnetic period length

72 mm

Number of period

34

Length of magnetic structure

2448 mm+ End blocks ( ~50 mm)

Minimum pole gap

20 mm

Numbers of blocks per period

4

Peak vertical field

0.76 Tesla

Peak horizontal field

 0.5 Tesla

Max. circ. poln field Bx=By

0.41 T

Magnetic block material

Nd-Fe-B  (Br =1.14 T)

Magnetic bock dimensions

18mm ´ 40 mm ´ 40mm

Figure 1: Arrangements of magnets and the end blocks for a 6 period Undulator.

Figure 2: 3D field variation of vertical field for zero phase, 20 mm pole gap and 72 mm period length.

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