us hg research collaboration workshop, slac, 2011 progress on hg wakefield accelerator development...

US HG Research Collaboration Workshop, SLAC, 2011

PROGRESS ON HG WAKEFIELD ACCELERATOR DEVELOPMENT

EUCLID&AWA COLLABORATION

A. Kanareykin for Euclid/AWA CollaborationEuclid Techlabs LLC


Euclid Techlabs LLC: DLA collaboration

Euclid Techlabs, Rockville, MD: - -C.Jing, S.Antipov, P.Schoessow, and A.Kanareykin -P. Avrakhov (FNAL)-S. Zou (NRL)

AWA of Argonne Nat. Lab, Chicago: Argonne Wakefield Accelerator:M.Conde, J.G.Power, R.Conecny, Z.Yusof, AWA and W.Gai

Naval Research Lab, Washington, DC-S.Gold- J. Butler

FACET Collaboration:SLAC, UCLAJ. Rosenzweig, G.Travish,M.Hogan…

THz:


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).


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


Drive Gun

Linac & Steering Coils Quads

Wakefield Structure

ExperimentalChambers 4.5 m

GVGV

YAG1 YAG2

Spectrometer

YAG5Dump/Faraday Cup

Slits

YAG4YAG3ICT1

ICT2 BPM

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

Materials for Dielectric Loaded

Acceleratorb a

Q

Cu

>100 MV/m gradient demonstrated


Materials

(f = 9,4 GHz)

tan

(f = 9.4 GHz)

Cordierite 4.50.2 210-4

Forsterite 6.30.3 210-4

Alumina 9.80.3 110-4

D-10 9.70.2 1.510-4

D-13 13.00.5 210-4

D-14 14.00.5 0.610-4

D-16 16.00.5 210-4

MCT-18 18.03% 110-4

MCT-20 20.05% 1.510-4

V-20 20.05% 310-4

V-37 37.05% 310-4

material tan, X-band /, 4 V/m BST+MgO 350-500 510-3 1.30

material tan, X-band tthermo-conductivity

diamond, 5.7 110-4 2500 W/m/0K

material tan, X-band tthermo-

conductivity quartz , 3.8 110-4 1.4 W/m/0K

Dielectric Materials for the HG Accelerator Applications*

Low loss microwave ceramic (1994-2011)

Composite ferroelectric (2003-11)

CVD Diamond (2005-11)

Quartz (2002-11)


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.


Transformer Ratio Experiment by joint effort from Euclid Techlabs and AWA*

Measured Enhancement

factor of R2/R1=1.31

Inferred R2=2.3

Reference: Schutt et. al., Nor Ambred, Armenia, (1989)

zd d

W -

W+

d

(z)

R2=3.4

(2007)

(2010) *talk J.Jing


Temperature tuning of 14 MHz/0K

forsterite BST(M)

Tunable DLA Temperature Tuning*

*C.Jing’s talk


Tunable DLA Beam Experiment*

*C.Jing’s talk

Temperature tuning of 14 MHz/0K

Wakefield

Frequency Shift


BST(M) Ferroelectric Based L-band High Power Tuner

30 ns switching time

Collaboration with Omega-P and FNAL

Pulse steepening on NL planar transmission line


26 GHz Power Extractor and BBU Experiment

BBU mitigation with quadrupole channel

20 nC beam; tapered F-D-F quad array


Transverse Beam Dynamics in the DLA

Distance behind the bunch, cm3210-1

Wak

efie

ld ,

MV

/m1

0,8

0,6

0,4

0,2

0

-0,2

-0,4

-0,6

0

5

10

15

20

25

0,01 0,05 0,1 0,15 0,2 0,25 0,3 offset, cm

Transverse field, MV/m

Collaboration with Dynamic Software and ANL


Multibunch BBU in the DLA

v=cR

R’Fr

Fz

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


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.

Comparison of the 7.8GHz Conventional and the Transverse mode Damped DLA structure.

Freq. Q in conventional DLA structure

Q in transverse modes damped DLA structure

Accelerating mode (TM01)

7.8GHz 6964* 6738*

Transverse modes (HEM11)

6.34GHz 6866* 23*

Collaboration with ANL

*C.Jing, this workshop


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 Modification This 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.


Developing a Dielectric PETS* (CLIC)

* Funded by DoE SBIR Phase I. Thanks for help from AWA, CLIC, and SLAC.

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

Freq 12GHz

Effective Length 23cm

Beam channel 23mm

Thickness of the dielectric tube 2.58mm

Dielectric const. 3.75(Quartz)

Q 7318

R/Q 2.171k/m

Vg 0.4846c

Peak surface Gradient 12.65MV/m

Steady Power 142MW


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.


• fast rf rise time (<3ns)Broadband (>150MHz)• less filling time Large (~10%c) Vg.

3ns 3ns

Trf=28ns

Tf=9nsTbeam=16ns

%26rf

beam

rf

sloadbeambRF T

T

P

LEI

6.5A 267MV/m

0.3m

1.264GW

16ns

25ns

Development of a Short Pulse High Gradient DLA Structure*

AWA/Euclid proposed a 26GHz short pulse collider concept.

RF pulse structure

Requirements for the accelerating structure

* Funded by DoE SBIR Phase I. *M.Conde’s talk


Broad band fast rise time

500MHz

DLA structure (const. impedance)

Design of the Short Pulse DLA

Broadband coupler (scaled from SLAC X-band coupler)

Vg~11%c; R/Q~22k/m; R~50.5M /m


Projected rf power and achievable gradient in AWA 75MeV beamline

Estimated PowerAWA facility

75MeV beam16 bunches60nC/per bunchz=2mm

26GHz DWPE

767MW, 15ns, 26GHz rf (10MeV

loss)

26GHz DLAEstimated Gradient

250 MV/m

talk M.Conde


Multipactor Studies

0 50 100 1500

5

10

15

20

25

MP

-indu

ced

pow

er lo

ss, %

gradient, MV/m

MAX SEY 2.4MAX SEY 5 Simulations:

Multipactor power loss decreases at

HG

Longitudinal Transverse

• groove type • groove dimensions• length• TiN coating

we are all set to test ~ 10 different configurations:

S.Antipov’s talk Collaboration with UMD,

NRL and ANL


Motivation for CVD Diamond for DLA

Element Six

Element Six

CVD DIAMOND PROPERTIES:

- DC BREAKDOWN THRESHOLD OF ~ 2 GV/m

- LOSS FACTOR DOWN TO 5-9 x10-5 AT 30-140 GHz

- HIGHEST THERMAL CONDUCTIVITY

- DC CONDUCTIVITY - HIGH REPRATE.

- MULTIPACTING CAN BE SUPPRESSED

- CVD DEPOSITION NOW CAN BE USED TO FORM CYLINDRICAL WAVEGUIDES


35 GHz Diamond Based DLA Structure

CVD diamond tube fabrication


500 600 700 800 900-5000

0

5000

10000

15000

20000

25000

30000

35000

cts

8-30

-1

Wavelength (nm)

center

500 600 700 800 900-5000

0

5000

10000

15000

20000

25000

30000

35000

cts

8-3

0-2

Wavelength (nm)

edge

500 600 700 800 900

Wavelength / nm

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

Cou

nts

High Electronic Quality Cylindrical Diamond DLA (I)


High Electronic Quality Cylindrical Diamond DLA (II)

Laser light

Laser light

Daylight

Outer surface facets

facets

cylindrical


Planar Diamond Structure

Bunch length 1.5 mm

Beam gap 4.0 mm

D thickness 1.2 mm

width 8 mm

length 5.0 mm

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


Planar Structure Design

Avoiding hot spots on diamond holder

beamDiamonds E6 ...scratched

There will be a ~500% field enhancement in the scratch / groove

beam


Diamond Groove SEM Image

SEM: Z. Yusof

Cut: J. Butler (NRL)

Image: “BEFORE”


The Structure Holder

Most the holder parts are completed

One modification needed (RF probe)

Cleaning (parts, diamonds)

S. Doran


SEE COEFFICIENT

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.

I.L. Krainsky et al. NASA Report/TP—1999-208692, (1999)

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).


ID=80 μm (a=40 μm )OD= 152 μm (b=76 μm)b - a= 30 μm (diamond thickness)

Planar or Cylindrical THz DLA ?Gradient

Distance behind the bunch, cm0

Wak

efie

ld ,

V/m

10,000,000,000

8,000,000,000

6,000,000,000

4,000,000,000

2,000,000,000

0

-2,000,000,000

-4,000,000,000

-6,000,000,000

-8,000,000,000

-10,000,000,000

b a

Q

w

0 5 103 0.01

1 104

5 103

0

5 103

1 104

z-Vt, cm

Ez, M

V/m

Both structures ~ 2 GV/m/nC

2a=80 μm, a= 40 μm, b= 70 μm b - a= 30 μm (diamond thickness)w= 300 μm

2 GV/m/nC 2 GV/m/nC


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

us hg research collaboration workshop, slac, 2011 progress on hg wakefield accelerator development...

Documents