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Status of Target Design. Chris Booth Sheffield 28 th October 2004. Outline. Specifications Diaphragm Spring suspension Linear Drive First prototype New design Plans. Draft Specification. Transit: 40 mm Entry ≥ 5 mm into beam in ≤ 2 ms (see plot). Target edge trajectory. - PowerPoint PPT Presentation
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Status of Target Design
Chris Booth
Sheffield
28th October 2004
Chris Booth University of Sheffield 2
Outline• Specifications
• Diaphragm Spring suspension
• Linear Drive
– First prototype
– New design
• Plans
Chris Booth University of Sheffield 3
Draft Specification• Transit: 40 mm
• Entry ≥ 5 mm into beam in ≤ 2 ms(see plot)
Chris Booth University of Sheffield 4
Target edge trajectoryWith spring
45
50
55
60
65
70
75
80
0 5 10 15 20 25 30
t (ms)
Posi
tion
(mm
)
beam
target
Chris Booth University of Sheffield 5
Draft Specification• Transit: 40 mm
• Entry ≥ 5 mm into beam in ≤ 2 ms(see plot)
• Cycle time: 20 ms
• Positioning accuracy: 0.5 mm
• Timing accuracy: ~ 0.2 ms
• Frequency: (baseline) 1 to 3 Hz on demand
• (optimal) 1 to 50 Hz
• Maximum proton rate: 1.41012 per second
Chris Booth University of Sheffield 6
Specs Continued• Must operate in vacuum and radiation
environment
• Must not interfere with ISIS operation!!
Chris Booth University of Sheffield 7
Diaphragm spring
Target
Array of coils Magnet(s)
Position measurement
Schematic design
Linear Drive
Chris Booth University of Sheffield 8
Diaphragm Spring suspension• Frictionless “bearing” allowing vertical movement• Must keep armature on axis to 0.2 mm (for
magnet and position monitor)• Design of small spring obtained from Tom
Bradshaw (RAL)• Scaled up to allow ≥40 mm travel• Finite element studies to check stress and lifetime
issues (Lara Howlett)• Be-Cu sheet procured• Wire-erosion performed in Eng. Dept. workshop
Chris Booth University of Sheffield 9
Diaphragm Spring
Chris Booth University of Sheffield 10
Linear Drive (1)• Tests with first prototype
– Moving magnet shuttle (2 magnets)– Static single/double coil excitation– No commutator
Chris Booth University of Sheffield 11
Chris Booth University of Sheffield 12
Armature
Chris Booth University of Sheffield 13
Armature
S N N S
Chris Booth University of Sheffield 14
Armature
S N N S
~ radial field
Chris Booth University of Sheffield 15
x o o x o o
Coils
Armature
o x x o x x
x o o x o o
x o o x o o
Coils
Armature
o o x o o x
x x o x x o
“3-phase” drive
x o o x o o
Coils
Armature
x o x x o x
o x o o x o
x o o x o o
Coils
Armature
x o o x o o
o x x o x x
1 3
42
Magnetic actuator plus Hall switches bipolar drive
Chris Booth University of Sheffield 16
However!• Current armature/coil design does not
give required acceleration– 280 N kg–1 at 20 A mm–2
– Need ~950 N kg–1
revised armature design current density 35 A mm–2 for short
pulses
• Effective cooling essential
Chris Booth University of Sheffield 17
Improved armature design
soft iron Nd-Fe-B magnets
Sectored magnets – fixed together with aircraft glue
Chris Booth University of Sheffield 18
Cooling• Coils potted in thermally conductive resin
• Water cooling circuit integrated into outer aluminium housing
– Resin inside vacuum housing?
• Coil temperature monitored with thermistors
• Possible to monitor magnet temperature too?
Chris Booth University of Sheffield 19
Radiation concerns
• Wasn’t possible to make in situ
measurements this autumn
• Radiation levels may be radically different
without target in operation
• Studying documented radiation hardnesses
• Still hope to make measurements at ISIS in
spring
Chris Booth University of Sheffield 20
Plans for next months• Complete revised design
– Optimised coil, armature design
– 3-phase switched drive circuit
• Currently mounting 1st prototype vertically on diaphragm springs– Measure lateral stability
– Debug position readout system, check read speed
– Develop cooling and temperature measuring system
• Switch to new drive as soon as available
• Develop control hardware & software
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