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

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.

Timeline of Project Research Data Collection Data Analysis Conclusions

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

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

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)

Data Collection

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

Data Analysis

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

Brief Demo of Analysis

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: 3.23-3.20 = .03 degrees S-Band per degree Celsius Small difference between MDL and L2 phase drifts with respect to temperature

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

Proposed Solutions to Drift Liquid Hydrogen Cooling Fiber Optics Beam Cavities

Acknowledgements Ron Akre Vojtech Pacak SULI Program Staff Fellow SULI participants

Questions?