Transcript Undulator Vacuum Chambers and System

The Extruded Aluminum Chamber…
FAC10/07
October 30, 2007
1
Greg Wiemerslage
[email protected]
Why the Aluminum Extrusion…
Relatively fast and inexpensive
We have experience
Built more than than 40 extruded aluminum insertion device
chambers used at APS
Built extruded aluminum insertion device chambers in use around
the world
Bessy II, SLS, CLS, Desy TTF
Minimal welding needed
Only a small, simple TIG weld on each end to attach a bi-metal
flange
Aluminum surface provides high AC conductivity
Magnetic permeability of the chamber not a problem
No need for surface coating
FAC10/07
October 30, 2007
2
Greg Wiemerslage
[email protected]
The disadvantages…
The as-extruded aperture is not smooth
enough to minimize wakefield effects.
The aperture must be polished to reduce
Wakefield effects.
New methods of polishing had to be explored to
reach an acceptable surface finish.
We have settled on an approach utilizing “abrasive
flow machining” technology.
FAC10/07
October 30, 2007
3
Greg Wiemerslage
[email protected]
Abrasive Flow Polishing…
Normally an abrasive media is pushed back and forth through a part
through the use of a hydraulic ram.
Our extrusion is greater than 10x longer than they are used to pushing through.
A custom built diverter directs the media out orthogonal to the hydraulic
ram.
A flange attaches our extrusion with the diverter, and the media then flows
out through our extrusion and drops into a bucket.
After some refinements, the process produces satisfactory results.
FAC10/07
October 30, 2007
4
Greg Wiemerslage
[email protected]
Best test results compared to the acceptability table…
Polishing Data for Best (fourth) Test Results
80
70
X(rms) slope - mrad
60
50
40
30
20
10
0
0
5
10
15
20
25
Z(rm s) slope - m rad
The average rms slope error of the internal aperture in both the X (transverse) and Z (longitudinal)
directions should ideally fall within the green or yellow sections of the acceptability table.
The green, yellow, orange and red symbols on the chart on the right are from the acceptability table.
Green is very desirable.
Yellow is acceptable.
Orange is not desirable.
Red should be avoided.
The blue diamonds are our data points. The red circle is the average of our data points—within the realm of
acceptability.
FAC10/07
October 30, 2007
5
Greg Wiemerslage
[email protected]
Prototypes were built…
To test the viability and mechanical
characteristics of the full length chamber we
had two prototype chambers produced.
Both chambers were cleaned, baked, vacuum
tested and mechanically measured.
The results were excellent.
FAC10/07
October 30, 2007
6
Greg Wiemerslage
[email protected]
Prototype 1 Results
After a learning curve, the chamber was able to be straightened to ±50µm.
We did find that adjustment screws must be located every 10” over entire
length to achieve desired straightness.
Location 1 Chamber Straightness
Location 3 Chamber Straightness
0.060
0.060
0.040
Bottom
Straightness (mm)
Straightness (mm)
Top
0.020
0.000
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
-0.020
-0.040
0.040
0.020
Top
0.000
1
2
3
4
5
6
7
8
9
10
11
-0.020
-0.040
-0.060
-0.060
Chamber Location
Chamber Location
Location 2 Chamber Straightness
Straightness (mm)
0.060
0.040
0.020
Top
0.000
-0.020
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Bottom
-0.040
-0.060
Chamber Location
FAC10/07
October 30, 2007
7
Greg Wiemerslage
[email protected]
12
13 14
15
Bottom
Prototype 1 Results, Cont’d
Vacuum Chamber Thickness
Thickness at Aperture (mm)
6.090
6.080
6.070
6.060
Atmosphere
6.050
Vacuum
6.040
6.030
6.020
1 2
3 4
5 6
7
8 9 10 11 12 13 14 15
Cham ber Location
The chamber wall thickness fell within ± 50 µm.
There was no appreciable change in chamber thickness within the accuracy of
measurement between atmosphere and vacuum measurements.
The calculated aperture height range = 50 µm.
FAC10/07
October 30, 2007
8
Greg Wiemerslage
[email protected]
Prototype 2 Results
The chamber was straightened to ±80 µm within 4 hours.
Could get within ±50 µm or better with minimal added effort.
Location 1 Chamber Straightness
Location 3 Chamber Straightness
0.060
0.040
Bottom
0.020
0.020
0.000
-0.020
1
2
3
4
5
6
7
8
9
Straightness (mm)
Straightness (mm)
0.060
Top
0.040
10 11 12 13 14 15
-0.040
-0.060
-0.080
Location 2 Chamber Straightness
-0.100
0.000
-0.020
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
Top
-0.040
Bottom
-0.060
-0.080
-0.100
-0.120
-0.120
0.060
-0.140
-0.140
0.040
Cham ber Location
Cham ber Location
Straightness (mm)
0.020
0.000
-0.020
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
Top
-0.040
Bottom
-0.060
-0.080
-0.100
-0.120
-0.140
Cham ber Location
FAC10/07
October 30, 2007
9
Greg Wiemerslage
[email protected]
Prototype 2 Results, Cont’d
Cham ber Thickness
6.120
Thickness (mm)
6.100
Aperture Height (Calculated)
6.080
Atmosphere
6.060
Vacuum
6.040
6.020
6.000
5.080
1
2
Aperture height (mm)
5.070
3
4
5
6
7
8
9 10 11 12 13 14 15
Cham ber Location
5.060
5.050
Atmosphere
5.040
Vacuum
5.030
5.020
5.010
5.000
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
Cham ber Location
The chamber wall thickness fell within ± 50 µm.
There was no appreciable change in chamber thickness within the accuracy of
measurements between the atmosphere and the vacuum measurements.
The calculated aperture height range = 80 µm.
FAC10/07
October 30, 2007
10
Greg Wiemerslage
[email protected]
Gap Tolerance Stack-up…
Chambers can be manufactured well within the specified thickness tolerance.
Chambers can be installed within the 250 µm tolerance allocated for chamber thickness
variation and installation error using a reasonable amount of effort and modified support
system.
The allocation should be switched so manufacturing tolerance is smaller and alignment tolerance is larger.
FAC10/07
October 30, 2007
11
Greg Wiemerslage
[email protected]
Vacuum Chamber Specifications
A draft Engineering Specification Document (ESD) is written. Requirements are
below.
Parameter
Value
Achieved
6.00 +.15/-.05 mm
6.00 – 6.10 mm
5.00 ± .08 mm
5.00 – 5.07 mm
3464.44 +0/-.20 mm
Not Measured
± 0.050 mm
± .05 mm on chamber 1
± .08 mm on chamber 2
Beam stay-clear radius around the chamber aperture axis
≥ 2.3 mm
2.46 mm worst case
Average rms slope error goal of aperture in both longitudinal and
transverse directions – best effort
See table
-
Average vacuum pressure
< 10-6 Torr
<5 x 10-7
All peaks ≤ 44 AMU
All peaks ≤ 44 AMU
6063 aluminum
6063 aluminum
Thickness of chamber at aperture
Aperture height
Overall flange to flange length
Vertical straightness of the mounted chamber after alignment
RGA mass scan
Vacuum chamber material
FAC10/07
October 30, 2007
12
Greg Wiemerslage
[email protected]
Prototype Vacuum Tests…
Neither Prototype Chamber had detectable leaks
present with a sensitivity of better than 2.0 x10-10
mbar.l/sec
Pumping from only one end, with the gauges on the
opposite end of the chamber, the ultimate pressure of
the first prototype chamber was 4.7 x 10-7 torr.
Pumping from only one end, with the gauges on the
opposite end of the chamber, the ultimate pressure of
the second prototype chamber was 1.2 x 10-7 torr.
Therefore the average pressure within both was better than 5.0 x
10-7 torr.
FAC10/07
October 30, 2007
13
Greg Wiemerslage
[email protected]
Prototype Vacuum Tests…
Separate tests were conducted on a piece of
the polished extrusion in parallel with the
mechanical tests on the unpolished
prototype chambers
Polishing process introduced no contaminants that
could not be removed by standard cleaning
FAC10/07
October 30, 2007
14
Greg Wiemerslage
[email protected]
Outgassing test results of the polished piece…
Pressure after baking was 7.9 x 10-9 torr
Residual outgassing is calculated at 2.4 x 10-13 torr.l/cm2.sec
Comparable to unpolished extrusion
RGA scans were also comparable to the unpolished prototypes
FAC10/07
October 30, 2007
15
Greg Wiemerslage
[email protected]
Other efforts continue…
The ESD is in review
The SOW for machining is signed off and
part of the requisition
We have requested budgetary estimates for
machining and begun writing requisitions
We have begun preparing our fabrication
facility specifically for the LCLS chambers
Shipping crates have been ordered
FAC10/07
October 30, 2007
16
Greg Wiemerslage
[email protected]
The Schedule…
Event
Original Completion
Date
Updated Completion
Date
Polishing of all extrusions
12/07/07
11/30/07
Machining of all extrusions
4/21/08
Chamber Processing at ANL
4/23/08
Ship Chambers 1-5 to SLAC
1/23/08
2/1/08
1-6
Ship Chambers 6-10 to SLAC
1/28/08
2/22/08
6-11
Ship Chambers 11-20 to SLAC
3/10/08
3/14/08
11-22
Ship Chambers 21-30 to SLAC
3/26/08
4/4/08
22-33
Ship Chambers 31-40 to SLAC
4/25/08
4/29/08
33-40
FAC10/07
October 30, 2007
17
Greg Wiemerslage
[email protected]
The Cost…
So far Extrusion
costs are within
original (WAG)
estimates +
contingency factor
FAC10/07
October 30, 2007
Cost Items
Updated Estimates and
Quotes…Oct 07
Extrusions
$11,165.44
Flanges
$41,310.00
Polishing Prep
$350.00
Polishing
$152,819.85
Straightening
$15,600.00
Machining
$238,400.00
Crating
$4,979.60
Surface Sampling
prep
$5,040.00
ANL labor
~$220,000
Total
$689,664.89
18
Greg Wiemerslage
[email protected]
Progress to Date…
All Extrusions prepared for polishing and sent to
Engineered Finishing Corporation (EFC)
Ends of extrusions are already machined to accept
mating flange
Control samples of the first 54 un-polished extrusions
were cut and sent for surface finish analysis
Polishing requisition awarded and polishing has
begun
Polishing process is ongoing
10 Chambers already partially polished
FAC10/07
October 30, 2007
19
Greg Wiemerslage
[email protected]