1. Drive Beam Feedforward and Compression
 Current layout
 Issues
 Ideas for changes in the layout

2. Current Layout Final Compression, Phase Correction PETS
First Compression,
Phase and Energy
Measurement
Combiner Rings
DB Accelerator
Gun

3. Issues
 Energy spread is limited, i.e. a huge R56 is required for compression
 An incoming energy jitter will cause a huge phase jitter
 The phase correction must allow a huge correction range while maintaining an accurate phase correction 12GHz)
 The correction kickers must be strong and accurate
 The kickers require a lot of space and will be expensive (remember that we need 48 of these systems)

4. Some ideas for layout changes 1
 Split phase correction in two parts => more accurate correction
 Zero total R56 behind final acceleration => phase becomes independent of energy jitter
Final Re-compression,
Phase Correction
PETS
DBA 2
First Re-compression,
Phase and Energy
Measurement
Final compression,
Phase Correction CR
Uncompression
DBA 1
Gun
First Compression,
Phase and Energy
Measurement

5. Some ideas for layout changes 2
 Since we don't expect any phase jitter to be induced in the beam lines behind the combiner rings* we could use a single correction system instead of 24 => simplify beam lines and reduce cost
*there might be some jitter from the loop, but this cannot be corrected in any case
Final Re-compression,
Phase Correction
PETS
First Re-compression,
Phase and Energy
Measurement
Final compression,
Phase Correction CR
DBA 2
Uncompression
DBA 1
Gun
First Compression, Phase and Energy Measurement

6. Some ideas for layout changes 3
 If the combiner rings and the loops could be build in a way that CSR is small even for final bunch lengths we could remove uncompression and re-compression. Phase measurement and correction could be integrated in the loops => simplify beam lines and reduce cost
Phase Correction via
orbit bump in loop
PETS
Phase Measurement
Final compression,
Phase Correction CR
DBA 2
DBA 1
Gun
First Compression, Phase and Energy Measurement

7. Some ideas for layout changes 4
 Again one can argue that we might not need 24 feed-forward systems on each side => simplify beam lines and reduce cost
PETS
Phase Correction via
orbit bump in loop
Final compression,
Phase Correction CR
DBA 2
Phase Measurement
DBA 1
Gun
First Compression, Phase and Energy Measurement