Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS LCLS Undulator Support/Mover System: Relay Rack Heat Dissipation & the Effects on the Overall System Jeff T. Collins

Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Background: During Operation, the Relay Rack Located Under Each Undulator System will Continuously Dissipate Approximately 150 Watts of Waste Heat. Concern Has Been Raised that the Relay Rack Heat Dissipation will Elevate the Temperature of the Girder and Undulator Body as Much as 1°C. Estimates of the Relay Rack Heating Effects on the Undulator System have been Analyzed by J. Welch (1/10/08 Memo, “Estimate of Localized Heating Due to 150W Rack”, Hot Rack Effect.pdf).

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Hello David, I estimated some of the localized heating effects a 150 W rack would induce when placed under an undulator segment. This estimate includes radiation heat transfer and makes a stab at combining free convection and forced convection, which are both significant. The attached picture is largely self explanatory. The outside of the rack will come up to 29 C and a boundary layer flow of warm (24.5 deg C) air will form around it. This warm air will rise, mostly vertically, and envelop a section of the undulator and the girder. Heat transferred to the undulator and girder at this location will conductively spread longitudinally, warming up the girder and segment, and then get transferred to the air. I think the estimated temperature changes are accurate to within a factor of ~ 1/2 to ~ 2X. - Jim 1/10/08 Memo from J. Welch to D. Schultz:

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing The Experiment: A Combination of Infrared Imaging and Thermocouple Measurements were Used to Determine the Actual Undulator System Heating Effects from the Relay Rack Under Worst-Case Conditions where No Forced Air Flow is Present Along the Undulator. The LTT Set-Up at the APS was Used for the Experiments. Prior to Experimentation, Background Air Temperature Fluctuations Were Recorded Over a Weekend Period to Assess Air Temperature Stability in the LTT Test Area. A 156 Watt Heater Attached to a Spool Piece Was Placed Inside of a Relay Rack and the Relay Rack was Placed in Position Under the Support/Mover System Girder. The 156 Watt Heater Was Turned On and Infrared Images Were Acquired at a Rate of 1 per Minute for a Total of 20 Hours (1200 Images). After the 20 Hour Period, Temperatures Were Recorded Using a Type T Thermocouple at Various Locations On and Around the Undulator System.

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing The Relay Rack: 156 Watt Heater Attached to Spool Piece Placed Inside of the Relay Rack

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing The Radiometer System: The FLIR SC-6000 Radiometer was Recently Purchased in 2007 Two Weeks Ago The System Was Calibrated Using an Extended Area Blackbody The Calibration Yields 0.1°C Absolute Accuracy for Infrared Thermal Imaging The Thermal Imaging Resolution is Better than 25 milliKelvin

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Ambient Air Temperature Fluctuations in the LTT Area: Friday 3 PM Monday 11 AM  Ambient Air Temperature Fluctuation ≈ 0.7°C Temperature (°C) 0Time (hours)

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Rack Heating 156 Watts.avi The Thermal Imaging Results: Images Were Acquired at a Rate of 1 per Minute Over a 20 Hour Period 1200 Images Were Acquired The Data Was Converted into a Movie Time versus Temperature was Evaluated at Several Points on the System PRESS BUTTON TO PLAY MOVIE

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing The Final Image After 20 Hours of Relay rack Heat Dissipation: Steady-State on the Relay Rack Surface is Reached in Approximately 3 Hours Variations Beyond Steady-State Track with Air Temperature Fluctuations ≈ 5.1°C Temperature Rise in the Center of the Relay Rack ≈ 1.16°C Temperature Rise on the Gusset Center ≈ 0.24°C Temperature Rise on the Girder Top Above the Relay Rack Unmeasurable Temperature Variation on the Undulator 0.31°C per Division Frame Number = Minutes

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Temperature Measurement Location Measured Temperature (°C) Floor Under the Undulator System Next to Relay Rack21.8 Inboard Wall Adjacent to Center of Undulator System22.4 Center Top of Relay Rack28.2 Hottest Spot on Top of Relay Rack (Rear Edge)28.9 Side of Relay Rack at Louvers32.3 Underside of Girder on Gusset Above Center of Relay Rack22.6 Edge of Girder Above Center of Relay Rack22.3 Top Center of Girder Above Center of Relay Rack22.1 Top Center of Girder at Upstream End21.9 Top Center of Girder at Downstream End21.7 Center of Undulator Above Center of Relay Rack21.7 Downstream End of Undulator21.7 Upstream End of Undulator21.8 Steady-State Temperature Measurements Taken at Various Points On and Around the Undulator System Using a Type T Thermocouple After 24 Hours of 156 Watt Relay Rack Heat Dissipation

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Conclusions: With 156 Watt Power Dissipation from the Relay Rack there is an Unmeasurable Temperature Variation on the Undulator. These Tests were Conducted Under Worst-Case Conditions with No 0.43 m/sec Tunnel Air Flow Along the Undulator. In Actual Operation with Tunnel Air Flow Present the Effects of Relay Rack Heat Dissipation Would be Even Less. The K-Value of the Magnets in the Undulator Will be Unchanged as a Result of the Heat Dissipation from the Relay Rack.

Jeff T. Collins Undulator Support/Mover System January 2008 LCLSLCLSLCLSLCLS Support/Mover System Testing Future Tests: Similar Tests Shall Be Performed Using an 800 Watt Load Contained Within the Relay Rack. An Attempt Shall be Made to Determine the Threshold Where Measurable Temperature Rise on the Undulator can be Observed as a Result of the Relay Rack Heat Dissipation.