SPECIFICATION FOR AN

MRBR 9.4 TESLA/400 MM/ASR

MAGNET SYSTEM

Prepared by:- Magnex Scientific Limited

The Magnet Technology Centre 6 Mead Road

Oxford Industrial Park Yarnton, Oxford OX5 1QU, UK

Tel : +44 (0)1865 853800 Fax : +44 (0)1865 842466 E-mail : sales@magnex.com www : magnex.com

Document Ref : TS1444D

Date : May 2006

Tech Spec TS1444D May 2006 2

CONTENTS 1. Description of System 2. The Superconducting Magnet i. General Description ii. Specifications iii. Superconducting Shim Coils 3. The Cryostat i. General Description ii. Specifications 4. Scope of Supply

Tech Spec TS1444D May 2006 3

1. DESCRIPTION OF THE SYSTEM The MRBR 9.4/400/ASR is a complete superconducting magnet system intended primarily for research studies on biological applications of NMR imaging (MRI) and NMR spectroscopy (MRS). The system essentially consists of a highly homogeneous superconducting magnet (400MHz 1H, 9.4 Tesla) housed in a horizontal room temperature bore (400mm), low-loss helium cryostat. Field shimming is accomplished using superconducting shim coils. The ultimate homogeneity specifications require room temperature shim coils. The system is complemented with a helium cryomonitor, and an emergency quench heater control unit. Two cryo-refrigerators are configured with the system to facilitate nominally zero helium consumption, and eliminate the need for a liquid nitrogen reservoir.

2. THE SUPERCONDUCTING MAGNET i. General Description The magnet is wound from multi-filamentary NbTi conductor with a high percentage of copper to superconductor. The windings are placed on a precision-machined aluminium alloy former and then fully vacuum impregnated for robustness and long-term reliability. The field homogeneity is defined over a 20 cm diameter spherical volume. Inevitably winding tolerances and small amounts of environmental influence will distort the central field. Corrections for these distortions are made in the first instance by superconducting shim coils located on a former surrounding the main coil. The ultimate homogeneity specification is achieved using a combination of passive and room temperature shims. The magnet coils are fully protected from accidental damage due to a quench by a passive resistor network located within the helium reservoir. In the event of the need to activate an emergency discharge of the magnet a quench heater circuit is incorporated within the windings. The magnet is designed to conservative levels of stress and mechanical stability to ensure reliable and stable operation. In addition, high quality superconducting wire is used to ensure that a highly stable magnet system is achieved.

Tech Spec TS1444D May 2006 4

ii. Specifications Magnet Type : Multi-coil superconducting Central Field : 9.4 Tesla (400 MHz 1H) Field stability measured a minimum : Less than 0.05 ppm/hour drift of 72 hours after energisation (Ultimate field stability expected less than 0.01 ppm/hr) Operating current : 215 Amps (nominal) Field homogeneity values Superconducting only shimmed : < 10 ppm over 20 cm DSV*

Fully shimmed : < 5 ppm over 20 cm DSV**

Fringe Field (position of 5 gauss contour) - (see customer interface drawing)***

Axially from magnet centre line : 5.0 metres Radially from magnet centre line : 3.6 metres * Defined as the peak to peak variations of points plotted over a seven plane plot on the surface of the stated spherical volume. ** Projected Specification *** Safety Note: In the event of a quench it is possible for the magnetic field to

momentarily bloom beyond this limit. For further details please consult the Magnex site planning guide for this magnet.

iii. Superconducting Shim Coils These coils are positioned on a non-conducting former surrounding the main coil in the helium reservoir. Each coil set is fitted with a superconducting switch for persistent mode operation. Coil Details:- Shims provided : Z1, Z2, Z3, X, Y, ZX, ZY, XY,

X2-Y2 Maximum recommended current : 25 Amps Coupling : All shims are designed to be

de-coupled from the main coil

Tech Spec TS1444D May 2006 5

3. THE CRYOSTAT i. General Description The cryostat is of zero boil-off design, consisting of a central all-welded stainless steel helium vessel which is surrounded by an aluminium cryocooled radiation shield. The complete assembly is contained within a stainless steel outer vacuum vessel with an angled service turret located centrally on top of the cryostat (see customer interface). The turret provides access to the helium reservoir for the demountable magnet leads, helium level probe, and helium transfer siphon. Separate turrets house two zero boil-off cryocoolers. The outer vessel has end-flange closures constructed from aluminium which are sealed to the main body and bore-tube by compressed rubber 'O' ring seals. The room-temperature bore-tube is constructed from stainless steel. The cryostat is supplied with a support stand that consists of load-spreading plates which have provision for fixing to the floor of the installation room. The helium reservoir contains approximately 5,000 litres of liquid helium, nominally there is zero helium usage. Cryogen level monitors are incorporated into the liquid helium vessel and the associated electronics provide liquid level display and low level alarms. A back-up liquid helium level probe is included for use in the event of failure of the primary probe. The probes will monitor helium levels continuously from empty to full conditions. ii. Specifications The cryostat is generally as shown in Figure 1. Full specifications for the system are as follows:- Dimensions: Length of cryostat : 2286 (± 10) mm Height including quench duct manifolds : 3214 (± 10) mm Room temperature clear bore (without : 405 mm shims and gradients) Room temperature bore-tube material : Stainless steel Centre of field to base of stand : 1431 (± 10) mm Cryostat end-flange to centre of field : 1143 mm Width of end-plates : 2900 mm Min ceiling height for cryocooler removal : 3530mm Weight of cryostat (excluding cryogens : 19,000 kg (approximately) and gradients)

Tech Spec TS1444D May 2006 6

Liquid helium cryogen details:- Volume for initial installation (includes : 12,000 litres (nominal) cooling the magnet from 77K to 4.2K, volume required to completely fill helium reservoir and to top-up helium reservoir after magnet energisation) Helium usage (quiescent) : Zero-boil off* (nominal) (static magnetic field, leads withdrawn) Liquid nitrogen cryogen details :- Volume for initial installation : 10,000 litres (pre-cool of magnet to 77K) No nitrogen required during normal operation. * The cryocoolers will be serviced once a year. Annual cryogen usage is

approximately 300L during coldhead service.

Tech Spec TS1444D May 2006 7

Tech Spec TS1444D May 2006 8

Tech Spec TS1444D May 2006 9

Tech Spec TS1444D May 2006 10

Tech Spec TS1444D May 2006 11

Tech Spec TS1444D May 2006 12

Tech Spec TS1444D May 2006 13

4. SCOPE OF SUPPLY

Standard Components

1. Magnex MRBR 9.4/400/AS superconducting magnet with integral shim coils housed inside a low loss horizontal bore cryostat with support stand.

2. Helium transfer siphon 3. Nitrogen blow out tube

4. Magnex E5083 cryogen monitor

5. Magnex E7007 emergency discharge unit.

6. Set of cables 8.5m long.

7. Demountable main current lead

8. Demountable shim lead

9. 2 off 2 stage coldhead

10. 2 off High voltage compressor (380-415V 50Hz, 460V 60Hz)

11. Set of flexible gas lines

12. Instruction manual

13. Spares kit

Optional Components Split service tools for low ceiling height Non magnetic platform to allow access to service turret