1. Phase II Commissioning
MATLAB Feedback
Phase II Commissioning
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

2. Questions / suggestions
Topics
New Block Diagram
Demo
New Requirements
Tradeoffs and other Issues
Questions / suggestions
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

3. Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

4. DEMO
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

5. New Requirements Additional Feedbacks Creating new feedback loops
Bunch Charge
Longitudinal will expand to include BC2 Energy and BC2 Bunch Length
No DL2 energy for now, see SLC BPMs below
L2 and L3 Launch
Creating new feedback loops
Who is the target user? User needs to be familiar with EPICS databases
I suggest a team; physicist+controls sw
Reading SLC BPMs
Longer response time
Throwaway code
We have 3 EPICS BPMs for longitudinal; allows 5x5 fully EPICS
Controlling SLC Magnets
There was discussion about leaving the correctors under SLC control, what are the tradeoffs there and is this a real option?
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

6. New Requirements Automatically switch configurations
MATLAB script must read these conditions from PVs and make decision on each iteration of the algorithm, since it cannot be ‘interrupted’; a cost in processing time
not ‘standard’ across feedbacks. May not be an issue now, but specialization means maintenance difficulties, and implementation difficulties looking ahead to fast-feedback
Runtime adjustment of gains, weighting factors, mask matrix
MATLAB script must read and apply these parameters from PVs at each iteration of the algorithm, whether they’ve changed or not. Also not ’standard’, see above.
Cascading Feedbacks
Longitudinal already satisfies this
Is cascading required for transverse?
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

7. Mask Matrix  Switching mode
Introduce a Mask Matrix MM
The user can design a specific feedback, may be needed in commissioning stage
The Mask Matrix can be multiplied on the Gain Matrix MG
Minimum modification to existing longitudinal algorithm
Performs unnecessary calculation to get the correction on the actuator
Yet, the correction is not applied (ie. Becomes 0 change)
The Mask Matrix can be “multiplied” on getting the measurement, so to stop the measurement and to stop unnecessary calculation
Yet, the framework stays the same
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

8. LCLS – Accelerator and Bunch Compressor Schematic
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

9. Example: 6 by 6  5 by 5 L3 Phase L3 Phase Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

10. Cascade Loops: Injector, L2, and L3 Launch
Identify transport matrices from loop i (=1 … n) to loop j (=i+1 … n)
Based on Model? How accurate is the model, if the n—loop and n+1—loop are separated too far physically?
We can measure the transport matrices
Injector launch is commissioned and worked well
For each stage n, similar implementation as that for injector launch
However, the measurement should subtract what comes from the upstream loop disturbance
If n is too large, this becomes cumbersome
Minimum modification, and the framework stays the same
Oct. 11, 2007
LCLS Physics Meeting
D. Fairley & J. Wu

11. The End Questions? Suggestions? Oct. 11, 2007 LCLS Physics Meeting
D. Fairley & J. Wu