BEPC-II magnet
project
The BEPC-II magnets are Interaction Region magnets to be used as part of
an upgrade to the Beijing Electron Positron Collider. Two magnets will
be produced, both of which will be inserted within the solenoidal
detector at one of the collision points.
Since the best use of the quadrupole focusing in this case requires
placing the magnet as close to the collision point as possible, these
magnets will be used within the magnetic field of the detector. This
constrains the materials that can be used for construction to only
non-magnetic materials. It also places severe demands on the structure
of the magnet and it’s holding supports due to the reaction forces
between the solenoid and the magnet.
To create the coil pattern for the final magnet, the coils will be
manufactured using the computer controlled 11 axis-winding machine.
Using ultrasonic energy, the cable is wound onto a support tube using a
welding technique commonly used in industry for joining plastics. Since
the magnet will be ramped relatively slowly, the use of 6 around 1 cable
is acceptable.
The coil set for both magnets include an 8 layer main quad coil, a 2
layer horizontal dipole, a 2 layer vertical dipole, a 2 layer skew quad,
and three anti-solenoid shield coils. The anti-solenoids are fabricated
using a rectangular MRI style wire. These coils will be placed around
different parts of the body of three coils. The inner diameter of the
main quad for SCQ1 is 10 cm, with the outer diameter being 20 cm. For
SCQ2, the inner is 12.2 cm, with 16.8 outer.
In all, there are 28 layers of superconductor used in this magnet, the
most complicated design to date, using somewhat over three miles of
superconductor.
Link
to initial R and D winding and tests
Link
to production winding
Movie of winding process (4 minutes
35 seconds)
Large file
(25 MB, 640x480, 30fps, 778Mbps)
Medium file
(16 MB, 320x240, 30fps, 490Kbps)
Small file
(1.4 MB, 160x120, 15fps, 45Kbps)
For more information contact
John Escallier
