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MA6 vertical field cryomagnet
Sample space dimensions
see Magnet List
Restrictions
| Instrument | Field Limit | Comment |
|---|
| DMC | 6 Tesla | |
| MARS | 6 Tesla | |
| TriCS | 6 Tesla | |
| PREP | 6 Tesla | in its trolley, far enough from "Kabelkanal" |
| HRPT | 6 Tesla | (measured forces below 200 N vertically and horizontally, even for xy table) |
| RITA II | 6 Tesla | with goniometer mounted (goniometer motors removed? - to be verified) |
| EIGER | 6 Tesla | with goniometer mounted (also gonio motors mounted) |
On EIGER the vertical force was less than 80 N at 4.2 Tesla -> no problem.
On all other instruments, to be evaluated before first use.
max. Forces on Magnet:
| horizontal | 500N |
| vertical | 500N |
Specifications
More Information on intranet page (Drawing): LdmWiki:MA6
Energisation rates (Tesla/min)
| Field range | Training mode (slow) | Normal mode (fast) |
| below 4.8 T | 0.1922 | 0.3844 |
| 4.8 ... 6 T | 0.0641 | 0.3844 |
Main Coils
| Guaranteed maximum central magnetic field | 6 Tesla |
| Current for full field | 93.661 A |
| Homogeneity over 15 mm diameter sphere | 1.0 % |
| Magnet clear bore diameter | 50 mm |
| Nominal inductance | 18.13 Henry |
| Switch heater current for open state | 65 mA |
| Current decay in persistent mode | < 1/10000 / h |
| Distance of magnetic field centre for base of cryostat | 165 mm |
| Neutron split | 40 mm |
| Vertical neutron access on a 15 mm sphere | ±15 deg |
| Horizontal neutron access | 340 deg |
Resistance values (Ohm)
| | RT | 77 K | 4.2 K |
| Magnet coil | 48.4 | 39.4 | 0.1 |
| Switch heater | 114.7 | 112.5 | 104.5 |
| Spare switch heater | 112.7 | 110.4 | 103.5 |
| Thermometer on coil (Allen Bradley) | 317.5 | 385 | 4560 |
General
| Liquid He evaoration rate (needle vale close, no current) | <275 cm3/h |
| Liquid N2 evaporation rate | 300 cm3/h |
| Useful liquid He volume | 22 l |
| Liquid N2 volume | 25 l |
| Approximate weight | 150 kg |
Field Homogeneity
Solved Issues
The following problems seem to be solved after repair at Oxford Instruments (Aug 2010)
- The magnet seems to have a cold leak, occuring only occasionaly at low temperatures.
As a workaround the main vacuum has to be pumped constantly. (Jul 2009)
- The magnet sometimes quenches (only above 4.8 T) -> solved by strictly obeying the
training mode ramps.
Attachments:
ma6_homogeneity.png
This particular version was published on 14-Sep-2020 12:19:42 UTC by MarkusZolliker.
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