2006 05 02 Booth

MICE Target Status: 

MICE Target Status Chris Booth Sheffield 2nd May 2006

Slide2: 

Focus of recent work has been assembly tests at RAL last week. Review of components Results of tests Preliminary follow-up plans

Components: 

Components Stator body Ceramic tube Glass readout tube Target shuttle Ceramic bearings Electronics Frame, jack, bellows, gate-valve

Stator (1): 

Stator (1) Micro-surgery on Manchester body has allowed insertion of ceramic tube! Tolerances around ceramic slightly tight. We have learned how to make all components for future stators in house.

Stator (2): 

Stator (2) Coil winding company provided satisfactory sample. 30 coils ordered – delivered 2 weeks ago. Coils wound in-house also satisfactory. Will try new cooling and potting techniques in future.

Ceramic tube: 

Ceramic tube Test flanges & dummy stator built at RAL. Indium vacuum seals tested. Pronounced satisfactory!

Optical readout enclosure: 

Optical readout enclosure Quartz glass tube and flange procured. Flange machined, tube fixed with cryostat cement.

Shuttle: 

Shuttle Oxford agreed to assemble shaft, target, alignment fin, stop, magnets, readout vane (see picture) – many thanks! Magnets, readout vane supplied by Sheffield. For prototype, shaft produced from steel tube rather than titanium. Assembly cleaned in Oxford, delivered direct to RAL.

Slide9: 

Titanium target Steel shaft Alignment fin Stop Magnets Optical readout vane

Ceramic bearings: 

Ceramic bearings Slot for alignment fin Hole for alignment pin

Control electronics: 

Control electronics Cards now rack-mounted. Extensive tests with prototype drive. Several hours pulsing at 0.3 Hz (10 A). Some reliability & noise problems to be addressed.

Bellows: 

Bellows

Slide14: 

Indium seals Ceramic bearings

Slide15: 

Beam pipe Gate valve Bellows Drive mechanism Support frame

Assembly test: 24-28 April: 

Assembly test: 24-28 April First time many parts came together: Stator first connected to electronics 20th Glass readout tube assembled 21st Target shuttle finished morning of 24th Some RAL parts and flanges not previously assembled.

What did we learn?: 

What did we learn? Glass tube is very fragile! Broken near metal flange. Ground down and re-glued – vacuum tested ok. New crack when tightened down onto full assembly. Covered in epoxy! Amazingly, this appeared to seal ok!

Slide18: 

Target shuttle was distorted Slot cut along thin-walled tube to take alignment vane caused shaft to distort. Vane was twisted and slightly off-axis at one end. Would not pass through ceramic bearing. Slot & hole in bearing machined out to allow shaft and vane to pass. Some play and roughness, but movement satisfactory.

Slide19: 

Indium seals did not work! Despite success with test pieces, could not pump down below 310–3 mbar. Flanges found to have too large diameter and chamfer; rebates incorrect so inadequate closure of seal. Attempts to seal with extra indium. Only partial improvement. Prevented vacuum quality checks with mass spectrometer.

Slide20: 

Temperature sensitivity Operation of drive (power-off to park position) caused deterioration in vacuum. Chilled water cooling (12°C) also worsened vacuum. Partial recovery on return to ambient temperature. Movement of ceramic tube disturbing (imperfect) seal?

Slide21: 

Optical readout block did not fit Insufficient space for readout block around glass tube when drive in raised position. Large guide flange removed – appears not to be necessary. Flange could also be machined down to allow space. Extremely difficult to align optics Higher refractive index of quartz tube? RAL restrictions on use of laser in hall.

Solutions: 

Solutions 1 & 6 Replace glass tube with steel plus flat glass windows Robust, much simpler optics. Redesign optical mounts to allow off-line alignment. 3 & 4 Flanges for indium seals to be re-ground or re-made Vacuum and temperature tests will be performed at RAL.

Slide23: 

2 Oxford redesigned target shuttle Target, shaft, stop, alignment fin machined out of single piece of titanium. Cross-shaped cross-section. Strong, no tendency to twist. Only magnets and readout fin to be added. New (or modified) ceramic bearings will be required – design to allow insertion of shaft through lower bearing for easier assembly.

Conclusions: 

Conclusions Still digesting results of last week! Despite problems, a lot was learned. Practical details of assembly for first time. Improved design of major components. No proper vacuum tests. No reliability or vibration tests. Review (with ISIS) 16th May. Will repeat assembly in hall. Unlikely to install in ISIS for June – perform thorough off-line checks for October access.