Trip Report from CERN and Wendelstein W7-X October 6 – 13, 2007 Michael Viola; Steve Raftopoulos; Bill Sands October 6-10 CERN Geneva, Switzerland October Wendelstein W7-X, Greifswald Germany

CERN Paparazzi Metrology – “Bill Sands” Discussed Metrology Met with Christian Lasseur and Raphael Goudard –Photogrammetry improves with increased number of pictures taken with less than 60 degree field of view –Should fill Frame with target but not to edge –Must cover at least 10 pixels of the CCD –Should turn camera on side and upside down often to allow software to compensate aberation errors. –Should take absolute minimum of 9 photos –Should have 1/3 overlap –Distance between camera stations 2/3 of the recorded distance –If b = 2/3 * 2.8 * 2.1 then uncertainty ~ mm Best achievable is.23 mm (offset of.019 mm) –Choice of reflectors center sizes 12, 15, 40 mm

Metrology

CERN Discussed Welding –Met with three: Gil, Stefano, Michelle –MIG is far better for distortion –Weld from center to outside of each stringer –Weld alternate from center then left right; right left

CERN Discussed Welding –An example of a 10mm plate is to the left with three passes of MIG. Note little distortion and excellent fusion

CMS

W7- X Welding

Wendelstein W7-X Welding Welding Equipment –MIG with active CO2 cooling of surface –NEW patented narrow gap weld tip for MIG –PT Drive improves feed Procedure –Weld from center to outside –Alternate from center out –Narrow GAP technique –Adjust weld to allow for narrow gap head Comments –Our TIG procedure: Way too many passes as a result of too small wire –.4mm (3/32”) = 7 passes –Should use 1.6 mm wire = 3 passes (much less heat) –Check opportunity for pre-deforming or clamping along longitude if possible –Distortion realized is >75% from root weld and complete when 50% of weld is finished

Wendelstein W7-X Welding Welding Recommendations Equipment –MIG with active CO2 cooling of surface –PT Drive improves feed –NEW patented narrow gap weld tip for MIG Procedure –Weld from center to outside –Alternate from center out –Narrow GAP technique –Adjust weld to allow for narrow gap head Comments –Use very experienced and well qualified welders. –It takes two 3 week periods to qualify even a good welder to perform reasonable Stainless steel MIG welds. –Distortion realized is >75% from root weld and complete when 50% of weld is finished –Welds configuration must be qualified with samples and pull tests 5 mm 6 mm 11 mm

Wendelstein W7-X Metrology Photogrammetry –Torsten, head of W7-X metrology and Bob Brade head of JET metrology. –Presentation compares difference between LTD and Photo LTD –R=40 m –ADM provides 10 microns + 50 microns –No loss for ADM really since encoders dominate error Photo –R=5 m –Uncertainty 0.2 mm

Wendelstein W7-X Metrology Laser Tracker Used for most of the work –Take three complete for each measurement After scans they then pick best one of the three to use.

W7- X

W7- X Metrology

Wendelstein W7-X NCSX Status review General comments W7-X metrology grew in 2 ½ years Karl’s Assembly control division had three planners at top for Status review Are shims qualified? Was flexibility of the coils a recent find? Having shims and bushings are overkill and raise cause for suspicion of design and questions. Add the risk of tooling not working after commissioning Tooling for installing ports from underneath –can Ports be installed with vessel supports in place TF Coil installation and stability of field period assembly as we add components TF and PF supports will likely cause distortion. –How is it compensated? Guys are so busy doing day to day tasks that there isn’t time to design the future needs The design of station 5 and 6 is of done so how can a review say confidently that the design cost and schedule can be met?

Wendelstein W7-X NCSX Status review Status review Once you do a bottom up estimate, you must make milestones based on final date back Did we meet all milestones to date? Contracts –How long did it take to provide similar structures? –Why should review team believe that new contracts are shorter [sanity check of similar tasks.] All prototyping must use same materials; same configuration; same procedures Have the design all been well defined (Stations 5 and 6) – wave of hand that it is just simple is not enough !!Station 5 and 6 are too rough!! Talk about the risks in the technique and have a plan B Understand all risky operations and have them accounted for. A technical review needs to dissect the assembly steps Formulate work to deal with remaining risky activities –Design, material, interferences, schedule –Allow for repairs Knoxville planning showed too many tasks in parallel responsible by same people. Must also provide an explanation of plan B for either risky tasks OR not well defined work If station 3,5,6 additional time were based on station 2 actual experience it would be more convincing. Allow for don’t know problems or missing designs Promote pessimism