PROGRESS ON HG WAKEFIELD ACCELERATOR DEVELOPMENT EUCLID&AWA COLLABORATION

1. A. Kanareykin for Euclid/AWA Collaboration Euclid Techlabs LLC PROGRESS ON HG WAKEFIELD ACCELERATOR DEVELOPMENT EUCLID&AWA COLLABORATION

2. Euclid Techlabs LLC: DLA collaboration AWA of Argonne Nat. Lab, Chicago: Argonne Wakefield Accelerator: M.Conde, J.G.Power, R.Conecny, Z.Yusof, AWA and W.Gai • Euclid Techlabs, Rockville, MD: - -C.Jing, S.Antipov, P.Schoessow, and A.Kanareykin • P. Avrakhov (FNAL) • S. Zou (NRL) THz: FACET Collaboration: SLAC, UCLA J. Rosenzweig, G.Travish, M.Hogan… • Naval Research Lab, Washington, DC • S.Gold • - J. Butler

3. DLA Issues • Drive Beam – Beam Train - High Gradient DLA • Dielectric Material Beam Tests • Dielectric - Wakefield Power Extractor • Tunable Dielectric Based Accelerator • Energy Transfer: High Transformer Ratio • Beam Handling, Beam Breakup (BBU) • Dipole Mode Damping Dielectric Based Accelerator issues: high gradient – drive beam, power extraction, tuning, efficiency, beam control (BBU).

4. Outline • Transformer Ratio Experiment (C.Jing’s talk) • Tunable DLA (C.Jing’s talk) and Nonlinear Materials for DLA • 26 GHz Power Extractor • BBU Studies for DLA • PETS power extractors • Short Pulse High Gradient DLA Structure (M.Conde’s talk) • Multipactor DLA Studies (S.Antipov’s talk) • GHz Diamond Based DLA Structure • FACET DLA

5. e Q 2b 2a Cu Materials for Dielectric Loaded Accelerator • Single bunch operation • Q=1-150 nC • Energy=15 MeV • High Current = 10 kAmp • Bunch train operation • up to 64 bunches x 50 nC  50 ns long >100 MV/m gradient demonstrated

6. thermo d material e t - tan , X - band conductivity 0 ´ diamond 5.7 2500 W/m/ K , 1 10-4 thermo d material e t - tan , X - band conductivity 0 ´ quartz 3.8 1.4 W/m/ K , 1 10-4 Dielectric Materials for the HG Accelerator Applications* Low loss microwave ceramic (1994-2011) Composite ferroelectric (2003-11) Quartz (2002-11) CVD Diamond (2005-11)

7. Euclid efforts in the WF experiments at Argonne • Experiment of 26GHz dielectric wakefield power extractor in 2009 • 16ns,1MW & 6ns, 20MW 26GHz rf pulse were measured. • BBU was observed. • Experiments of transformer ratio enhancement in 2007, 2010 • Successfully enhanced the transformer ratio to 3.4 by using ramped bunch train technique. • The tunable DLA demonstration with the beam test in 2010. • Developed the tunable DLA structure, bench tested. Beam test has been completed few weeks ago. Tuning range of ½ λ has been demonstrated • The planned test of the GHz diamond structure • Finished simulation and engineering design. The planar structure is being assembled. Beam experiment - in Spring of 2011. Progress on cylindrical structure development.

8. + r (z) W - W z d d d Transformer Ratio Experiment by joint effort from Euclid Techlabs and AWA* (2010) *talk J.Jing R2=3.4 Measured Enhancement factor of R2/R1=1.31 Inferred R2=2.3 Reference: Schutt et. al., Nor Ambred, Armenia, (1989) (2007)

9. Tunable DLA Temperature Tuning* forsterite BST(M) Temperature tuning of 14 MHz/0K *C.Jing’s talk

10. Tunable DLA Beam Experiment* Frequency Shift *C.Jing’s talk Wakefield Temperature tuning of 14 MHz/0K

11. BST(M) Ferroelectric Based L-band High Power Tuner Collaboration with Omega-P and FNAL Pulse steepening on NL planar transmission line 30 ns switching time

12. 26 GHz Power Extractor and BBU Experiment BBU mitigation with quadrupole channel 20 nC beam; tapered F-D-F quad array

13. Transverse Beam Dynamics in the DLA Collaboration with Dynamic Software and ANL

14. Multibunch BBU in the DLA • 3D beam implementation • Phase space input/output • Parmela files import opportunity • Improving Particle Push Algorithm (3D) • 2D FODO focussing F(x)~x, F(y)~y • Improved results visualization • Main parts to be ready by February 2008

15. 7.8 GHz Transverse Mode Damped DLA Structure* • A new transverse mode damped DLA structure has been proposed. • A 7.8 GHz prototype has been built and bench tested. • Beam test will be performed at AWA facility. Collaboration with ANL *C.Jing, this workshop

16. Projects • Development of a Dielectric-Based Short RF Pulse Two Beam Accelerator Prototype Module Unlike the most of the present accelerator designs pulse with lengths of 150-400 ns and gradients ~100 MV/m as the operational parameters, we propose a short pulse (~20 ns), high repetition rate (>1 kHz), high gradient (>200 MV/m) accelerator technology. • THz Dielectric Wakefield Accelerating Structure. This project will develop a manufacturing technology of artificial diamond fiber to be used in dielectric loaded accelerating structures. When developed, this structure will sustain a record high accelerating gradient in THz frequency range. • Development Of A 12 GHz Dielectric-Based Wakefield Power Extractor for Potential CLIC Applications Dielectric based high power radio frequency (rf) generator offers the possibility of reduced cost and higher efficiency for applications in the next generation high energy physics machine to meet the particular requirements of CLIC. • Multipactor Suppression In Dielectric Loaded Accelerating Structures Using Vacuum Channel Surface ModificationThis project will study ways to eliminate a form of energy absorption that is currently the main obstruction to widespread use of the dielectric based particle accelerators. • Dielectric Collimators for Linear Collider Beam Delivery this project will develop a special device to control electron bunch of the future linear collider. The use of new software and materials that our company has developed is expected to lead to improved performance and efficiency.

17. Developing a Dielectric PETS* (CLIC) In order to have a high power rf test at SLAC, the 1st structure is scaled to 11.424GHz. 12GHz Quartz-Based Power Extractor Using CLIC Parameters: σz=1mm, Q=8.4nC, Tb=83ps * Funded by DoE SBIR Phase I. Thanks for help from AWA, CLIC, and SLAC.

18. 12 GHz PETS is under construction: The rest of parts are on the lathe; will be done this week, then will be shipped for the brazing.

19. Development of a Short Pulse High Gradient DLA Structure* RF pulse structure Trf=28ns AWA/Euclid proposed a 26GHz short pulse collider concept. 3ns 3ns 6.5A 0.3m 267MV/m 16ns 1.264GW Tbeam=16ns Tf=9ns 25ns Requirements for the accelerating structure • fast rf rise time (<3ns)Broadband (>150MHz) • less filling time  Large (~10%c) Vg. *M.Conde’s talk * Funded by DoE SBIR Phase I.

20. Design of the Short Pulse DLA Broad band  fast rise time DLA structure (const. impedance) 500MHz Vg~11%c; R/Q~22k/m; R~50.5M /m Broadband coupler (scaled from SLAC X-band coupler)

21. Projected rf power and achievable gradient in AWA 75MeV beamline 26GHz DWPE Estimated Power AWA facility 75MeV beam 16 bunches 60nC/per bunch z=2mm 767MW, 15ns, 26GHz rf (10MeV loss) talk M.Conde Estimated Gradient 26GHz DLA 250 MV/m

22. Multipactor Studies Longitudinal Transverse we are all set to test ~ 10 different configurations: • groove type • groove dimensions • length • TiN coating Simulations: Multipactor power loss decreases at HG S.Antipov’s talk Collaboration with UMD, NRL and ANL

23. Motivation for CVD Diamond for DLA • CVD DIAMOND PROPERTIES: • - DC BREAKDOWN THRESHOLD OF ~ 2 GV/m • LOSS FACTOR DOWN TO 5-9 x10-5 AT 30-140 GHz • HIGHESTTHERMAL CONDUCTIVITY • DC CONDUCTIVITY - HIGH REPRATE. • MULTIPACTING CAN BE SUPPRESSED • - CVD DEPOSITION NOW CAN BE USED TO FORM CYLINDRICAL WAVEGUIDES Element Six Element Six

24. 35 GHz Diamond Based DLA Structure CVD diamond tube fabrication

25. High Electronic Quality Cylindrical Diamond DLA (I)

26. High Electronic Quality Cylindrical Diamond DLA (II) Laser light Laser light cylindrical Daylight facets Outer surface facets

27. Planar Diamond Structure • First CVD diamond in a dielectric accelerating structure • > 100 MV/m gradient using AWA beam • Breakdown test using 20 micron – wide artificial scratch on the diamond surface (0.5 GV/m level fields) Structure is short, TM110 – based . Wake is a single mode at ~ 26 GHz

28. Planar Structure Design beam Diamonds E6 ...scratched Avoiding hot spots on diamond holder There will be a ~500% field enhancement in the scratch / groove beam

29. Diamond Groove SEM Image Image: “BEFORE” SEM: Z. Yusof Cut: J. Butler (NRL)

30. The Structure Holder Most the holder parts are completed One modification needed (RF probe) Cleaning (parts, diamonds) S. Doran

31. SEE COEFFICIENT • Collaboration: • - NRL, Surface Chemistry (J.Butler) • Genvac Aerospace Inc./NASA • Coating Technology Solutions, Inc. A.Kanareykin, P.Schoessow et al, EPAC 2006, Edinburgh, pp. 2460-2462, (2006). I.L. Krainsky et al. NASA Report/TP—1999-208692, (1999) Multipacting is suppressed by treating the diamond surface during the CVD growth of the diamond, in particular, dehydrogenation of the surface to decrease the secondary electron yield. SEE coefficient is reduced ~ 1.

32. Planar or Cylindrical THz DLA ? Gradient ID=80 μm (a=40 μm ) OD= 152 μm (b=76 μm) b - a= 30 μm (diamond thickness) 2a=80 μm, a= 40 μm, b= 70 μm b - a= 30 μm (diamond thickness) w= 300 μm e 2 GV/m/nC 2 GV/m/nC Q 2b 2a w Both structures ~ 2 GV/m/nC

33. Conclusions • Transformer Ratio Experiment has demonstrated R>3.4 for two bunch train • Tunable DLA has been developed with the tuning range of 15 MHz/0 • 26 GHz Power Extractor has been demonstrated • BBU code has been developed and used for PE development • 12 PETS power extractor for CLIC is under construction • High Gradient DLA Structure proposed for the new Short Pulse collider • GHz Diamond Based DLA Structure test are coming • Multipactor simulations showed reduced power loss at 150 MV/m • FACET DLA structure is being fabricated