2 June 1995
To: Distribution:
From: Stan Ecklund
Subject: "IR +- 1m Engineering" Meeting Notes 2 June 1995
Martin show a drawing of a section through Q1 with current
dimensions as best known. An interference of 8 mm still exists
between Q1 outer radius and support tube inner radius. The
minimum required thickness of the Q1 containment and the support
tube is of interest. Can the interference come out of these
thickness?
Stan showed the calculated Q1 strength for several inner and outer
radii. The CDR had 0% margin for Brem=1.05 Tesla. With 32
sectors instead of 16 one gains 5.8%. At this point it is
desirable to allow 10% for packing of material and any
inefficiencies . The table shows the required inner radii for
various outer radii keeping the required strength with 10% margin.
A potential solution with two Q1 segments was shown with only the
first having a trim coil. This allows a 10 mm decrease in outer
radius, with a 4.6 mm decrease in the inner radius. But this puts
the beam closer to the magnetic material causing a harmonic
problem.
Mike showed that the harmonics are a problem when the beam is too
close to the magnetic material. The beam is already at a radius
which gives a 1E-4 field error. Tracking studies have shown the
need for a 32 sector magnet.
Roy and Alex discussed status of looking for smaller custom cable
packages. They are considering flat parallel wires over ground
plane geometry. Electrically these require an active driver and
are not as desirable. Time scale for more information is after
Liverpool meeting.
Suggestions for resolving the space problem:
* increase diameter of support tube about 40 mm. - this results in
reduced tracking resolution.
* design Q1 as a composite quadrupole and dipole. - more
complicated Q1. Forces and demagnetizing fields must be
considered.
* use NdFe permanent magnet material, with higher Brem= 1.15 - 1.2
Tesla. - down side is larger dM/dT coefficient and larger
radiation sensitivity.
Tom reported Dave Coupal's progress with shielding studies. He is
updating GEANT geometry to current B1 and Q1 configuration. He is
considering tungsten shielding inside of Q1 on side not occupied
by the beam.
Dieter and Ron Rogers showed the latest water manifolds for the Be
beam pipe. In order to avoid a water to vacuum braze joint, they
put in an air vent. This requires the water spacing increase from
1 mm to 1.5 mm. We calculate the outer radius is still less than
the CDR value and should not be a problem for the vertex chamber.
The increase does increase the radiation lengths. They have
designs with and without a flange on the HER upbeam end.
John showed a heat calculation of the B1 mask with a newer
simplified geometry. The beam on/off temperature difference for
the magnet is of order 4.9 deg. C. This could be regulated with a
feed forward system controlling water temperature sensing beam
current. Maximum thermal stress is 24 KPSI, to be compared to a
GlidCop fatigue stress of 30KPSI. John pointed out that the film
drop at the water surface is equivalent to 19 mm of Cu conduction
path, so moving the water closer will not improve heat transfer
significantly.
Correct notes from 5/19/95: read 140 deg C temperature, not
temperature rise; temperature rise is 120 deg C.
Action Items:
1. Find solution to Q1 interferences. [Martin, Stan, Mike,..]
2. Look for ways to reduce cable interferences. [Roy]
How much z space at Q1 inboard end is needed?
3. Consider ways to make B1 support smaller. [Martin]
4. Temperature Specifications for B1, Q1. [Hobey]
5. Drawing Updates: [Martin Nordby, Fred Goozen]
Shielding, rotated BPM, Radial Ion pump,...
6. HOM RF calculations with new mask geometry. [Eddie Lin]
7. Check that a rotated BPM misses synchrotron rad fan. [Mike]
8. Maintain list of support tube parameters. [Hobey]
add Q1 radii, offset, support barrel radii,...
9. Can we do with less shielding between B1 and Q1? [D. Coupal]
10. Refine Be cooling flow manifold, details. [Dieter]
11. Required thickness of Q1 containment. [Martin]
12. Required thickness of Support Tube. [Martin]
13. Mask cooling calculation. [J. Hodgson]
Next Meeting: 13:00 Friday 9 June 1995 in the Yellow room with TV
to LBL
attachments: transparencies