| Line 1 was replaced by line 1 |
| - !!MA7 |
| + !!6.8 Tesla Horizontal Field Cryomagnet MA7 |
| Line 3 was replaced by lines 3-15 |
| - This new 6.8 Tesla horizontal field cryomagnet has strong stray fields due |
| + The horizontal high field cryomagnet has a restricted neutron access. |
| + There are 4 windows of 45 deg each, valid for a sample of 15 mm diameter. |
| + For larger samples, the opening angle for full access is sligthly smaller. |
| + In the field direction, the vertical access is +- 22.5, in fact, the access |
| + is a cone. Perpendicular to the field direction, the access is +-6.7 deg on |
| + a 15 mm sample, or 65 mm parallel access. |
| + |
| + [MA7/MA7coils.png] |
| + |
| + For access with polarized neutrons, an asymmetric mode (max. 6.2 Tesla) |
| + is available. This is needed when a beam perpendicular to the field is used. |
| + |
| + This cryomagnet has strong stray fields due |
| Line 8 was replaced by lines 20-24 |
| - !Restrictions on RITA-II |
| + [MA7 Specifications] |
| + |
| + More information on intranet page (drawing): [LdmWiki:MA7] |
| + |
| + [MA7 Restrictions] |
| Lines 10-11 were replaced by line 26 |
| - Provisional force measuremnents on RITA-II have shown that |
| - the operation of MA7 on Rita-II is allowed: |
| + [MA7/MA7pict.jpg] |
| Lines 13-67 were replaced by lines 28-58 |
| - * between 3.0 and 18.0 meV (a2 >= 37 deg) at a distance of 450 mm or more, up to 4 Tesla |
| - * between 3.0 and 8.0 meV (a2 >= 56 deg) at a distance of 450 mm or more, up to 4.4 Tesla |
| - * between 3.0 and 8.0 meV (a2 >= 56 deg) at a distance of 540 mm or more, up to 5.5 Tesla |
| - |
| - For any other configuration force tests have to be done. |
| - As soon as the approriate adapter plate is avaliable, we should |
| - repeat the force measurments. |
| - |
| - Original data: |
| - ||a2 [[deg] || distance [[mm] ||field [[Tesla] || force [[N] || extrapolated field [[Tesla] for 500 N || allowed field with security margin |
| - | 56 | 540 | 4.8 | 230 | 6.8 | 5.5 |
| - | 56 | 450 | 3.4 | 180 | 5.5 | 4.4 |
| - | 37 | 450 | 3.4 | 220 | 5 | 4 |
| - |
| - [MA15RitaRestrictions/SampleTableDistance.jpg]\\ |
| - How the distance has to be measured. |
| - In this example the distance is around 400 mm. |
| - |
| - !Restrictions on AMOR |
| - |
| - Provisional force measuremnents on AMOR have shown that |
| - the operation of MA7 on AMOR is allowed with a field perpendicular |
| - to the beam at least up to 4 Tesla (estimation: 5 Tesla). |
| - The distance to the shielding wall between AMOR and SANS-II has |
| - to be at least 540 mm, measured from the aluminium window |
| - (or about 870 mm to the magnet centre). |
| - |
| - ''Torque Calculations'' |
| - |
| - In general, the forces are not only radial, but also tangential, |
| - inducing a torque onto the magnet. For estimating the forces |
| - on the fixation, we need to take into account the distance of |
| - the fixation points from the coil center. |
| - |
| - For MA7, with a mean coil radius of about 100 m and fixation points |
| - at about 150 mm for the coil center, we get the following: |
| - |
| - Ro: object distance (mm)\\ |
| - phi: angle (deg) between field direction and direction of object, for maximum force on fixation\\ |
| - Fp: force when object on magnet axis (in field direction) |
| - Ft: maximum total force on fixation |
| - |
| - ||Ro ||phi ||Ft / Fp |
| - |<600 | 0 | 1.0 |
| - | 800 | 20 | 1.04 |
| - | 1000 | 27 | 1.13 |
| - | 1200 | 32 | 1.25 |
| - |
| - For the distance to the shielding wall we have to add 1/5 of the edge |
| - distance for the mean distance of the material that has to be taken |
| - into account (870 * 6/5 = 1044 mm). |
| - |
| - Measured force at 3.4 Tesla: 180 N. |
| - Extrapolated to 5 Tesla: 390 N. |
| - Factor 1.2 for including torque: 470 N. |
| + [MA7/asysym.jpg] |
| + !Asymetric mode |
| + |
| + For changing from symmetric mode to asymmetric mode and vice versa: |
| + |
| + * on the top of the magnet under the aluminium cyclinder: |
| + ** make sure that the magnetic field is zero (IPS: shown current is 0 AND "persistent mode" LED is off) |
| + ** switch the magnet power supply IPS off |
| + ** open the cap using the screws marked on the picture above |
| + ** switch the cable from the SYM pin to ASY pin (or vice versa) |
| + ** the cable connected to the COM pin must always stay connected |
| + ** close the cap |
| + ** switch the magnet power supply on |
| + * change the configuration of the IPS: |
| + ** press RAISE+LOWER+LOC/REM simultanously ("tESt" and "t 00" appears) |
| + ** press LOWER to go to "t 07", and then LOC/REM (""SUP" and "S 00" appears) |
| + ** press LOWER 5 times to go to "S 11" and then press LOC/REM (the induction value appears) |
| + ** press and hold LOC/REM and change the value with RAISE or LOWER, release LOC/REM when done |
| + ** press RAISE 7 times to go to "S 02" and then press LOC/REM (the value for max. current appears) |
| + ** press and hold LOC/REM and change the value with RAISE or LOWER, release LOC/REM when done |
| + ** press LOWER once to go to "S 01" and then press LOC/REM (the value for max. current appears) |
| + ** press LOC/REM again (the value for max. field appears) |
| + ** press and hold LOC/REM and change the value with RAISE or LOWER, release LOC/REM when done |
| + ** press LOWER once to go to "S 00" and then press LOC/REM ("tESt" and "t 00" appears) |
| + ** press LOC/REM again ("Stor.y" appears) and again |
| + |
| + ||Parameter || Value for Sym || Value for Asym |
| + |S11 (coil inductance) | 112 | 78.7 |
| + |S02 (max. current) | 96.636 | 100.657 |
| + |S01 (max. field: second value)| 6.8 | 6.2 |
| + |
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