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JSPWiki v2.0.52

Restrictions for MA7




InstrumentAllowed maximum field [Tesla] Conditions
AMOR 4 field perpendicular beam
AMOR 6.8 field parallel beam
RITA-II 4 ... 6.8 see below
SANS-I 6.8 / 6.2 (full field) with spin flipper only when field perpendicular to beam
SANS-II 6.8 / 6.2 (full field)
TASP 6.8 see below (A3 does not move > 4 Tesla)
EIGER 6.8 / 6.2 (full field)goniometer removed
ZEBRA 6.8 / 6.2 (full field)L1 = 1500 mm, L2 = 785 mm (1D detector)
ZEBRA 5 / 5 L1 = 1000 mm, L2 = 785 mm (1D detector)

Restrictions on RITA-II

Goniometer removed.
Provisional force measuremnents on RITA-II have shown that the operation of MA7 on Rita-II is allowed:

  • 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 (we had a quench at 6 Tesla!)
  • between 3.0 and 13.68 meV (a2 >= 42.7 deg) at a distance of 680 mm* or more, up to 6.8 Tesla

* at a distance of more than 680 mm or a2 angles < 42.7 the analyser tank touches the wall at a4 ~= 45

For any other configuration force tests have to be redone.

MA7 Original Data

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. 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.
With a reasonable security margin, we allow to go up to 4 Tesla.

Restrictions on TASP

Goniometer removed.
Beryllium Filter Distance 27 cm (see photo)
Sample table - Monochromator - 73 cm

A2 a4 Allowed field
-92 < A2 < -41 (Ei=14.7 meV)<= 119 6.8 Tesla

WARNING: Motor A3 may not move with a field > 4 Tesla

This data is derived from the force test 7. July 2015:
4.8 Tesla, horizontal force 150 N (towards Beryllium filter), vertical force 180 N.


Restrictions on SANS

Allowed up to maximum field independend of the field direction.

With spin flipper only when field perpendicualr to beam and in asymmetric mode. Other configurations with spin flipper have to evaluated.

Force measurements (without spin flipper):

field direction field horizontal force vertical force
parallel to beam 4.9 Tesla 80 N 340 N
perpendicular to beam 4.9 Tesla 110 N 180 N

Force Test on SANS-II 21.5.2015

4.9 T perpendicular to beam300 N vertical140 N horizontal
4.9 T parallel to beam300 N vertical60 N horizontal

Attachments:  distanceTASP.jpg  taspFilterMA7.png 
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This page last changed on 18-Sep-2020 09:35:18 UTC by MarkusZolliker.