1. Walter Wuensch CLIC project meeting, 31 March 2015 Accelerating structure program: design and testing

2. Walter Wuensch CLIC project meeting, 31 March 2015 Our current prototype structure designs date back to 2007/2008. There have been many important developments since then, with a cumulative effect which motivates launching a new set of prototypes. Highlight the developments and the logic for designing new CLIC baseline structures. Review other new structures in the pipeline; baseline alternatives, other applications and structures built by collaborators. Update the high-gradient testing program Introduction

3. Walter Wuensch CLIC project meeting, 31 March 2015 High-gradient data and analysis Comp atible with previo us result at 29 MW input power

4. Walter Wuensch CLIC project meeting, 31 March 2015 Progress in understanding and feedback on rf design

5. Walter Wuensch CLIC project meeting, 31 March 2015 LHC results, energy staging and rebaselining  Most efficient structure is very similar to CLIC_G

6. Walter Wuensch CLIC project meeting, 31 March 2015 Consequences We are now launching a new series of prototype baseline CLIC accelerating structures for high-gradient testing: CLIC-G* - Optimized 3 TeV structure, new cell shape, constant ΔT, optimized damping features. Higher performance. CLIC-G*-with-SiC – Smaller overall transverse size, revised mechanical design of vacuum manifolds, new loads. Simpler, cheaper design. Two more are being defined but we don’t yet have final decisions: CLIC-380 – Features as above but for entry energy, lower gradient but same rf constraints. Understanding, publicity, first structure needed. CLIC-ST – Strongly tapered design. Depends on results of beam-loading experiment. Complex to understand but significant potential performance increase.

7. Walter Wuensch CLIC project meeting, 31 March 2015 Timescale CLIC-G* and CLIC-G*-with-SiC – 2 nd half 2016 CLIC- 380 - End 2016, early 2017 CLIC-ST - Hmmm Quantities need to be decided before procurement. Parameters fixed rf design mechanical design procurementassembly 12-18 months

8. Walter Wuensch CLIC project meeting, 31 March 2015 Structure in halves by SLAC. Potentially cheaper, hard materials, preconditioned surfaces possible. Choke-mode damping by Tsinghua. Potentially cheaper Four XFEL structures by SINAP. New application with large potential. High-gradient proton funded by KT. New application. Additional new accelerating structures

9. Walter Wuensch CLIC project meeting, 31 March 2015 Two TD26CC built and tested by KEK. Still unbeaten production! One TD26CC built by CIEMAT. Next step after PETS. Two T24s built by PSI in their production run. Vacuum brazing alternative, benchmark for their production line. One T24 built by SINAP. Potentially leads to large X-band installation. Whole structure in industry – Technical specifications are under preparation. Industrialization, cost estimate. New accelerating structures in the pipeline built by collaborators

10. Walter Wuensch CLIC project meeting, 31 March 2015 A now a look at our testing program XBox-1 and 2 clear since they run. Delivery, installation, commissioning and testing for XBox-3 is work in progress. Big job. Steadily increasing testing capacity should more or less coincide with the arrival of all the new structures.

11. Walter Wuensch CLIC project meeting, 31 March 2015 Shorter Term Priorities Repeat TD26CC - Consolidate (finish) CLIC baseline point. Validate compact coupler design. First TD24-SiC in low-breakdown rate regime. Complements SiC structures in module. Repeat T24 – We have not been able to reproduce KEK T24 result with CERN (beam-loading) or Tsinghua (first try) fabrication. Questions our fabrication quality Means relative performance of damped/undamped still an open question Reference for XFEL Waveguide components; rf valve, 3D printed components, controlled fabrication. For once test before installing… Will use Toshiba klystrons during installation/commissioning of XBox-3.

12. Walter Wuensch CLIC project meeting, 31 March 2015 Test stands status overview XBox-1 – T24, beam loading experiment ongoing and will continue. XBox-2 – Finish crab cavity, TD26CC next. XBox-3 – Under preparation. NEXTEF – Finish Tsinghua-built T24. KEK-built TD24R05 next. ASTA – Commissioning clone of our NI-based control system. KEK/SLAC-built TD24R05 installed and ready to go.

13. Walter Wuensch CLIC project meeting, 31 March 2015 Conclusions New CLIC baseline structures are being designed and should begin to be ready for test late next year. New structures are also in the pipeline baseline alternatives built by collaborators other applications XBox-1, XBox-2 and NEXTEF running and producing important results. XBox-3 coming on line during this year. Even ASTA is about to start up. Fabrication developments, pulsed dc, single cells, fundamental high-gradient studies, alternative materials another day.

14. Walter Wuensch CLIC project meeting, 31 March 2015 Upcoming events