Zian Zhu Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001

The solenoid magnet provides an axial magnetic field of about 1.2 Tesla over the tracking volume of BESIII,field uniformaty <5%. The magnetic field produced by the coil is returned by the steel plates of the surrounding Muon detector. (~12 layers in barrel,space for endcap,proper aperture of end yoke for SC quadruple) Compositive field with SC quadruple Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Coil Detector Magnet System Cryostat Field Mapping Power Supply Quench Protection Yoke (Barrel/End) Chimney Control Dewar Cryogenics

Magnet Characteristics Cryostat Inner Radius1.0 m Outer Radius1.3 m Total Length3.4 m Nominal Magnetic Field1.2 T Cool Down Time< 7 days Quench Recovery Time< 1 day Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 The field uniformity and forces on the coil are strongly influenced by the proximity of the iron yoke. We will calculate the field and forces using the ANSYS program. Magnetic Field Design B along Z axis (B0=1T, Poisson method)

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Flux line display (Poisson method)

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Cooling Tube Coil Design Super Conductor Support cylinder Chimney Cryostat

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Parameters of the Solenoid Coil Cryostat Inner Radius1.0 m Outer Radius1.3 m Length3.4 m Coil Effective Radius1.15 m Length3.0 m Conductor Dimension3 x 33 mm2 Outer cylinder Thickness15 mm Center Field1.2 T Nominal Current 3000 A Inductance 6.12 H Stored energy9 MJ Stored energy/cold mass(E/M)6 kJ/kg Charging time 0.5 hour Effective cold mass 4.3 tons

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 * We can benefit from other successfully solenoid magnets, particular the BELLE coil. * The primary issue regarding conductor fabrication is the cross sectional aspect ratio of the conductor. Co-extruded cable: the superconducting cable is at the center of the aluminum stabilizer. We will compare in several conductor options. Here is a conductor BELLE using: 3x33 mm2. * Stability against a quench: Even if the total magnetic energy were dumped entirely into the conductor, the material of the 33 mm thick coil should be sufficient to keep the coil temperature below 80 K after a quench at the operating current. * The coil consists of a single layer aluminum stabilized superconductor coil wound around and glued on the inner surface of an aluminum support cylinder. * The electric ground insulation between the coil and the support cylinder must have breakdown voltage larger than 2kV. Superconductor Cross section

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Coil Cross View

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Cryostat Radiation shield Cooling: 2 phase force flow Lhe circulating through the tube welded on the outer surface of the support cylinder. 2mm thick pure aluminum strips are wound on the inner surface of the coil to increase the propagation velocity of the quench Vacuum vessel inner/outer vessel connected by flat annular bulkheads at each end, made by non magnetic metal

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Coil Support Sketch map, Detail study is under investigation

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Chimney The cryogenic lines and the superconducting leads from the coil go through the chimney to the outside of the iron structure. The lines and leads are surrounded by multi layer thermal shields and the vacuum jacket. The chimney protrudes vertically up ward from one end of the coil. The annular space between the thermal shield and the vacuum jacket is occupied by the flow channels for the pressure relief and vacuum exhaust lines. Pressure relief is needed to protect the vacuum vessel from overpressure in the event of an accidental leak of cryogens from the cooling line. The relief device and vacuum pump are located on the top of the detector. A hole of dimension 50x50 cm2 in the iron yoke accommodates the chimney.

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Cryogenics Common cryogenics with mini beta magnet 150W+80W

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Power Supply 3000 A and 10 V Dump resistor needed Protection circuit Three modes of switching and discharging for the extraction of the electromagnetic stored energy from the magnet. Fast discharge system: quickly switch off the circuit and extract the energy to the dump resistor. This mechanism must work during power failures. Quench protection: It is required to have sufficient redundancy in the fast discharge system and quench detectors for safe quench protection. Slow discharge system: discharge the coil sufficiently slowly so that the eddy current in the coil will not initiate a quench.

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Force Calculations The radial magnetic pressure The Hoop stress The compressive force The axial stress The combined stress Mechanical Design

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Schedule ~ : Concept design/Engineering design : order conductor ~ : Coil fabrication, test cryogenics,mapping machine,power supply : shipping ( ~ ): Disa. BESII ( ~ ):Assembly iron yoke,cryogenics commission ( ~ ):SC solenoid and quadruple magnet commission ( ~ ):Field mapping

Superconducting Solenoid Magnet BESIII Workshop Zian Zhu Beijing, Oct.13,2001 Need Support from Domestic and Overseas Concept design Coil/Cryostat fabricate Chimney Power Cryogenics Filed mapping