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 |
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.
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 |
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 |
Allen-Bradley and Rhodium-Iron Temperature Sensor Characteristics
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 |