1. Analysis of the Phase Drift in the Main Drive Line and L2 Reference Lines along the LCLS Using MATLAB
By: Guy Grubbs II

2. Introduction
The Main Drive Line (MDL) and L2 Reference Line (L2) at the Stanford Linear Accelerator Center are used in timing the klystrons which power the accelerator structure.
These signals will be involved in accelerating a very finely compressed bunch of electrons which must travel on phase of the electromagnetic (EM) waves that come from the klystrons.

3. Timeline of Project
Research
Data Collection
Data Analysis
Conclusions

4. Research
Main Drive Line: Expansion Joints securely fastened to concrete floor along accelerator
L2: Heliax cable used, dielectric increases velocity of RF wave to compensate for additional distance travelled

5. Thermal Expansion Happens in signal lines as well
Change in distance changes amount of power delivered to accelerator structure

6. Data Storage The Stanford Linear Collider Control Program (SCP) system
Experimental Physics and Industrial Control System (EPICS) system
Head to Tail Monitor
Temperature
Slow Phase and Amplitude Controller (SPAC)

7. Data Collection

8. Data Collection (cont.)
Collected every 6 minutes
Ran at all times
Checks for old data each time program is started
Will continue running until the array is filled if left to itself

9. Data Analysis

11. Data Analysis (cont.) Updates to new data on being run
Outliers eliminated
Displays relationships between different data
Allows user to set parameters quickly and easily

12. Brief Demo of Analysis

13. Results
Average drift from sectors 22-24: 3.23 degrees S-Band per degree Celsius
Drift at sector 25: 3.20 degrees S-Band per degree Celsius
Difference in L2 and MDL phase drift from sector 22 to sector 24: = .03 degrees S-Band per degree Celsius
Small difference between MDL and L2 phase drifts with respect to temperature

14. Results (cont.) Sector 29 has a very low correlation coefficient (.37)
Sector 30 has a nonlinear relationship
27-28 Feedback may be causing problems, or monitors need replaced
Sector 30

15. Proposed Solutions to Drift
Liquid Hydrogen Cooling
Fiber Optics
Beam Cavities

16. Acknowledgements Ron Akre Vojtech Pacak SULI Program Staff
Fellow SULI participants

17. Questions?