Analysis of the Phase Drift in the Main Drive Line and L2 Reference Lines along the LCLS Using MATLAB

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
10
(No Transcript)
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 3.23-3.20 .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?