5 Specifications and Test Results
5.1 Magnet Specification
5.1.1 Main Magnet
Symmetric Energisation:
Guaranteed maximum central magnetic field at 4.2K: 8.0 Tesla Guaranteed maximum central magnetic field at 2.2K: 9.0 Tesla
Current for central field of 8 T | 100.75 A |
Current for central field of 9 T | 113.34 A |
Field / Current ratio | 0.0794 T/A (794 Gauss/Amp) |
Nominal inductance | 88 Henries |
Asymmetric Energisation:
Guaranteed maximum central magnetic field at 4.2K | 4.0 Tesla |
Current for central field of 4 T | 91.35 Amps |
Field / Current ratio | 0.0438 T/A (438 Gauss/Amp) |
Nominal inductance | 46 Henries |
Neutron access
340 degrees in horizontal plane |
+-6 degrees onto 24 mm on axis in vertical plane. |
Switch heater current for open state | 75 mA |
5.1.2.Resistance Values (Ohm)
| Room Temp | 77 Kelvin | 4.2 Kelvin |
Magnet resistance Start-End Sym | 47.4 | 35.9 | 0.1 |
Magnet resistance Start-End Asym | 45.6 | 30.8 | 0.1 |
Persistent mode switch resistance | 50 | 210 | 205 |
Switch heater resistance | 214 |
Magnet to cryostat isolation (at 500v) | >20 M | >20 M | >20 M |
Main magnet to switch heater | >20 M | >20 M | >20 M |
Carbon resistors for lambda point refrigerator |
R1 | 142.0 | 163.0 | 976.0 |
R2 | 153.7 | 176.6 | 1021 |
R3 | 166.8 | 189.3 | 1015 |
R4 | 164.9 | 185.5 | 1062 |
5.2 Magnet Energisation
Energisation Rate
Symmetric Energisation:
Energisation Current (A) | Energisation Rate (A/min) |
0 to 75 | 3.0 |
75 to 90 | 2.0 |
90 to 100.75 | 1.0 |
100.75 to 113.34 Important: only at 2.2 K! | 0.5 |
Asymmetric Errergisation:
Energisation Current (A) | Energisation Rate (A/min) |
0 to 75 | 5.0 |
75 to 91.35 | 2.0 |
Achieving Persistent Mode
Maximum rate of change of current in the magnet current leads with the magnet in persistent mode (switch heaters off) is: 120 Amps/minute. This rate is programmed into the PS120-10.
For TAS7 users:
Note: For fields > 5T, tilt and translation motors GU,GL,TU,TL must be removed. This prevents the problem of the magnet pulling sideways and touching the inner LN2 shield.
5.3 Typical Lambda Point Performance
Resitance values of carbon resistors
R1 (kOhm) | R2 (kOhm) | R3 (kOhm) | R4 (kOhm) | approximate time after starting operation (min.) | Pressure (mbar) |
0.976 | 1.021 | 1.015 | 1.062 | 0 | 1000 |
0.976 | 1.022 | 1.153 | 1.311 | 10 | 45 |
0.981 | 1.448 | .1343 | 1.492 | 20 | 40 |
0.989 | 1.670 | 1.568 | 1.721 | 30 | 40 |
1.015 | 1.997 | 1.900 | 2.051 | 40 | 30 |
1.100 | 2.860 | 2.595 | 2.780 | 50 | 30 |
1.097 | 3.252 | 3.140 | 3.272 | 60 | 30 |
1.190 | 4.075 | 4.115 | 4.321 | 70 | 30 |
3.840 | 4.080 | 4.390 | 5.130 | 80 | 30 |
| | | | | Start to energize magnet from 8 T to 9 T. |
3.850 | 4.090 | 4.420 | 5.640 | 115 | 30 |
| | | | | 9 Tesla achieved |
3.860 | 4.100 | 4.440 | 5.930 | | |
5.4 Cryogenic Performance
Useful helium capacity | 45 litres |
Nitrogen capacity | 43 litres |
Typical liquid helium boil off rate at 4.2 K (no current in magnet leads, VTI needle valve closed) | 330 cc/hr |
Typical liquid nitrogen boil off | 630 cc/hr |
" when current in the leads | < 750 cc/hr |
5.5 Appendix
Allen-Bradley and Rhodium-Iron Temperature Sensor Characteristics
- Typical values of temperature versus resistance for an Allen-Bradley carbon resistor with nominal resistance at room temperature of 100 ohms and 270 ohms.
- Typical values of resistance versus temperature for a 4-wire Rhodium Iron sensor with a nominal resistance of 27 ohms at 273 Kelvin.
- Please note that this sheet is a guide for cooldown monitoring purposes only, and is not a substitute for a full calibration.
Temperature (Kelvin) | Allen-Bradley (100 Ohm) (Ohm) | Allen-Bradley (270 Ohm) (Ohm) | Rhodium-Iron (Ohm) |
500 | | | 51.4 |
475 | | | 48.2 |
425 | | | 42.8 |
373 | | | 37.5 |
323 | | | 32.2 |
300 | 100 | 270 | 29.8 |
280 | 100.5 | 273 | 27.8 |
260 | 101 | 276 | 25.7 |
240 | 102 | 280 | 23.74 |
220 | 103 | 285 | 21.73 |
200 | 104 | 290 | 19.69 |
190 | 104.5 | 293 | 18.67 |
180 | 105 | 296 | 7.66 |
170 | 106 | 299 | 16.64 |
160 | 107 | 304 | 15.87 |
150 | 108 | 309 | 14.53 |
140 | 109 | 314 | 13.46 |
130 | 110 | 320 | 12.37 |
120 | 112 | 326 | 11.38 |
110 | 114 | 334 | 10.24 |
100 | 116 | 343 | 9.2 |
95 | 117 | 348 | 8.7 |
90 | 118 | 354 | 8.18 |
85 | 120 | 360 | 7.68 |
80 | 122 | 367 | 7.19 |
75 | 124 | 375 | 6.72 |
70 | 126 | 384 | 6.27 |
65 | 128 | 395 | 5.82 |
60 | 131 | 407 | 5.43 |
55 | 135 | 420 | 5.05 |
50 | 140 | 435 | 4.73 |
45 | 145 | 455 | 4.43 |
40 | 150 | 485 | 4.17 |
35 | 158 | 520 | 3.94 |
30 | 170 | 560 | 3.75 |
28 | 175 | 580 | 3.67 |
26 | 180 | 610 | 3.6 |
24 | 190 | 640 | 3.53 |
22 | 200 | 680 | 3.45 |
20 | 210 | 730 | 3.36 |
18 | 225 | 790 | 3.28 |
16 | 241 | 860 | 3.18 |
14 | 269 | 980 | 3.07 |
12 | 300 | 1120 | 2.95 |
10 | 350 | 1350 | 2.81 |
9 | 390 | 1510 | 2.73 |
8 | 440 | 1770 | 2.65 |
7 | 520 | 2170 | 2.56 |
6 | 625 | 2700 | 2.45 |
5.5 | 700 | 3100 | 2.4 |
4.5 | 950 | 4500 | 2.28 |
4.2 | 1050 | 5000 | 2.25 |
4 | 1150 | 5500 | 2.22 |
3.75 | 1300 | 6200 | 2.19 |
3.5 | 1500 | 7100 | 2.16 |
3.25 | 1700 | 8400 | |
3 | 2100 | 10000 | |
2.8 | 2400 | 12300 | |
2.6 | 2950 | 15000 | |
2.4 | 3500 | 19500 | |
2.2 | 4400 | 25500 | |
2 | 5650 | 35000 | |
1.9 | 6800 | 41000 | |
1.8 | 8000 | 49000 | |
1.7 | 10000 | 60000 | |
1.6 | 12400 | 83000 | |
1.55 | 14000 | 100000 | |
Approximate % error due to magnetic fields:
Allen Bradley Resistors:
Field | 8 T | 14 T |
2K | 1.5 | 4 |
4.2K | 3 | 6 |
77K | 0.5 | 1.5 |
Rhodium-Iron Resistors:
Field | 1 T | 3 T |
2K | 0.14 | 0.88 |
4.2K | 0.13 | 0.79 |
50K | 0.14 | 0.84 |
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This page last changed on 16-Feb-2005 14:09:11 UTC by MarkusZolliker.
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