1. CLIC Klystron-based Design
D. Schulte for the CLIC team
D. Schulte, Klystron-based Design, January 2017

2. D. Schulte, Klystron-based Design, January 2017
Introduction
Goals
Develop conceptual design of the first energy stage
Design of lattices
Beam dynamics studies
Design optimisation with other groups (e.g. module)
Klystron-based alternative
Develop concept for the principle of the energy upgrades
Explore issues arising from upgrades and address important ones
Experimental activities
Contribution to experiments
Evaluation of impact of experimental programme on design
Explore opportunities of further experiments
Explore upgrade options based on novel technologies
Deliverables
Lattice decks
Specifications
Layouts
Reports
Will not cover details of work
Will evolve with results
Mainly give idea of scope and get going on things
Maybe wait with discussions until the end
D. Schulte, Klystron-based Design, January 2017

3. Klystron-based First Stage
Example RF unit design
(I. Syratchev)
With simple cost model find similar cost than drive beam-based design at 380GeV
Much improved RF unit design
More expensive at 3TeV
1076 units /beam
The pulse compressor used for parameter determination in the Baseline Report has been still a previous version
But used updated model
D. Schulte, Klystron-based Design, January 2017

4. Optimisation Procedure
Optimised cost systematically similar to drive beam-based design
Boundaries respected
Beamstrahlung level consistent with experimental request
Risk for the structure is slightly less than for 3TeV machine but the same for all designs
Beamdynamics constraints
50Hz operation
Some increase of risk in damping rings mitigated by increased horizontal emittance
Beam stability in main linac is constant (single and multi-bunch)
BDS is at the limit for the energy
Note: some effects are reduced, some are increased but not by large numbers
D. Schulte, Klystron-based Design, January 2017

5. Klystron-based Design Cost Model
Ph. Lebrun, G. Riddone, I. Syratchev
Based on:
Scaling of CE and infrastructure cost
Analytic estimate of module cost
Analytic cost of RF unit
D. Schulte, Klystron-based Design, January 2017

6. Reminder: New Structure Choice
D. Schulte, Klystron-based Design, January 2017

7. Reminder: Selected 380 GeV Beam Parameters
109
5.2 nb
352
frep Hz 50
ex/ey
mm/nm
0.95/30
bx/by
mm/mm
8.2/0.1
sx/sy
nm/nm
149/2.9 sz mm 70
Ltotal
1034cm-2s-1
1.5
L0.01
0.9 ng dE % 6
The emittances are nominal values at the IP
Draft values for emittances targets are
Exit of damping ring
ex < 700nm, ex < 5nm
Exit of RTML
ex < 850nm, ex < 10nm
Exit of ML
ex < 950nm, ex < 20nm
A limited flexibility exists for the collision parameters O(10%) since the beam size is larger than the minimum that could be achieved
Also the waist shift allows to gain a few percent
D. Schulte, Klystron-based Design, January 2017

8. Remember: CLIC Energy Stages
Ecms=380Gev, L=1.5x1034cm-2s-1, L0.01/L>0.6
For higgs and top production, specified by CLIC physics group
Ecms=O(1.5TeV)
Depends on LHC findings
Ecms=3TeV, L0.01=2x1034cm-2s-1, L0.01/L>0.3
Klystron-based first energy stage has to be consistent with energy upgrade
Bunch charge of > 4x109
> 312 bunches
D. Schulte, Klystron-based Design, January 2017

9. Rational and Cases to be Explored
Ideal would be to have the same structure design for the scenario with drive beam and with klystrons
The first energy design should be consistent with an energy upgrade keeping the initial structures and adding other designs
Reference is the drive beam-based design for 380GeV (DB244):
use the same structure but with klystrons
upgrade with other structures and power old structures with klystrons or new drive beam modules
ideal solution if it works
Exploration 1 (K244):
find the best solution for a structure that can be used with drive beam or klystrons and is compatible with the upgrade
could replace the reference case
Exploration 2 (K):
find the best structure for the use with klystrons
ensure that is compatible with an energy upgrade if these structure are continued to be powered by klystrons
N > 4x109
N > 312
Pulse length 244ns
Any pulse length
D. Schulte, Klystron-based Design, January 2017

10. Klystron-based Design Structure Choice
Expect significant cost increase compared to optimised structure for klystron-based design
D. Schulte, Klystron-based Design, January 2017

11. Klystron-based Design Structure Choice
Slightly better cost for structure that is optimised for klystron-based design
Very slight increase in cost for drive beam-based design
D. Schulte, Klystron-based Design, January 2017

12. Klystron-based Design Structure Choice
Significantly better cost for structure that is optimised for klystron-based design
For the upgrade cannot use this design with drive beam
D. Schulte, Klystron-based Design, January 2017

13. Selected 380 GeV Beam Parameters for KN
109
3.87 nb
485
frep Hz 50
ex/ey
mm/nm
0.66/30
bx/by
mm/mm
8.2/0.1
sx/sy
nm/nm
120/2.9 sz mm --
Ltotal
1034cm-2s-1
1.5
L0.01
0.9 ng dE %
The emittances are nominal values at the IP
Draft values for emittances targets are
Exit of damping ring
ex < 500nm, ex < 5nm
Exit of RTML
ex < 600nm, ex < 10nm
Exit of ML
ex < 630nm, ex < 20nm
A limited flexibility exists for the collision parameters O(10%) since the beam size is larger than the minimum that could be achieved
Also the waist shift allows to gain a few percent
D. Schulte, Klystron-based Design, January 2017

14. D. Schulte, Klystron-based Design, January 2017
Conclusion
For the klystron-based design, significant cost saving could be expected from the scenario K compared to DB244
Proposed strategy is to refine the optimisation for this point and to explore two structures DB244 and K
Igor’s changes in the pipeline
issues with previous design
different pulse compressors
higher efficiency 12GHz klystrons …
When can we base a design on these?
in particular experimental verification schedule
Cost model should be reviewed
Power model will be needed
Should review impact of different parameter sets on all systems
How much change is required?
Iterations might be required
D. Schulte, Klystron-based Design, January 2017