Advanced Accelerator R&D: Flat Beam Transform & Emittance Exchange

Kwang-Je Kim ANL & U of C

June 27, 2008

ANL-UChicago-FNAL Collaboration Meeting at Fermilab

2ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Emittance Exchange and Flat Beam Transform Emittance Exchange (EEX): Complete exchange between x- and z-phase spaces: (x,z) (z,x)

Flat Beam Transform (FBT): Transform a round photo-cathode beam to a flat beam with a desired emittance ratio in (x,y) phase space

Applications often require a combination of these manipulations

3ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Flat Beam Transform Produce angular-momentum dominated beam and remove correlation

– R. Brinkmann, Y. Derbenev, and K. Floettmann (1999, 2001)

Experimentally demonstrated at A0– D. Edwards, et. al., emittance ratio of 40 at Fermilab A0 (Linac2000,

PAC2001)

– Yin-e Sun, U of C thesis (2005)

– Ph. Piot, Y.-e. Sun, and KJK, emittance ratio>100 (PRSTAB 9, 031001, 2006)

4ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Emittance Exchange Scheme First dogleg provides dispersion at deflecting cavity. The cavity reduces the momentum spread of the beam and gives

a shear deflection to the beam. The second dogleg finishes the exchange. The scheme improves on the previous approximate scheme by

Cornacchia and Emma in which the second dog-leg is reversed.

final e- bunch

Initial e- bunch

x < z

D1

x > z

D2 D3

D4

3.9 GHz TM110

Diagram by Tim Koeth.

5ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Improve HG X-Ray FEL Performance(P. Emma, Z. Huang, P. Piot, KJK)

Electron bunch emittance of current X-ray FEL projects is (xymwith Q=1 nC

This is about 10 times larger than ideal (to match the x-ray beam phase space)

Due to small energy spread, can make zm

FBT: (xy, zmExchange x & z (xy, zm

Q=30 pC, z=10 fs

• Higher gain

• Lower K

• Lower E-energy

6ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

To Obviate Electron Damping Ring from ILC Emittances of ILC electron bunches are

(xyzm

These bunches are produced by a 5 GeV, 6 km damping ring Theemittance Txy)1/2 is too small for photocathode

A possibility: (1, 1, 8)(50,0.02, 8)(8, 0.02,50) (Ph. Piot)

7ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

EEX Demonstration Experiment FNAL/A0

– Initiated by Helen Edwards, December, 2006, and T. Koeth engaged

– (x, y, z): ()(120, 6, 6)m, Q=1 nC

– Use CKM cavity design and existing RF power– Exciting dataTim will be able to graduate!

ANL/AWA-NIU-TsingHua U– Argone Acclerator Institute activity, funded by LDRD

– (x, y, z): ()(3,3,10)m , Q=0.1 nC

– NIU (Marwan Rihauoi, GS) and Tsinghua U (defl. cavity)– To be finished by 2010-2011

ANL-FNAL collaboration– Bi-(Tri-) weekly meetings and common web page– Especially productive in exchanging ideas on diagnostics

8ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

A0 People Helen Edwards – The Boss

– Don Edwards Ray Fliller (The Manager) Yin-e Sun (Recently from ANL) Jinhao Ruan – Laser, All things optical Jamie Santucci – Operations Tim Koeth – Rutgers Ph.D. Student Artur Paytan – Yerevan U. Ph.D. Student Mike Davidsaver – UIUC staff, controls Grigory Kazakevich – Guest Scientist, OTRI Manfred Wendt – Instrumentation, BPMs Randy Thurman-Keup – Instrumentation, Interferometer Vic Scarpine – Instrumentation, OTR and cameras Alex Lumpkin – Instrumentation, Radiation Diagnostics (On leave from ANL) Ron Rechenmacher – CD, controls Lucciano Piccoli – CD, controls Gustavo Cancelo – CD, Low Level RF Wade Muranyi – Mechanical Support, Lead Tech. Many Others from AD/RF, AD/MS

9ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Use a 3.9GHz, 5 cell copper cavity based on the CKM SRF deflecting cavity cooled with liquid N2.

An 80 kW klystron is available.

A0 Photoinjector Layout with EEX beamline

EEX at FNAL-A0

DipolesVertical Spectrometer

3.9 GHz TM110 (deflecting mode) Cavity

10ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

First Deflected Beam by a CKM type Cavity

Operating phase for exchange

11ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Recent Measurements at A0( Tim Koeth)

TM110 cavity strength, ko

Vary cavity strength

record vertical BPM reading

Intro p from 9-Cell

OFF73%90%100%105%

Verti

cal B

eam

Pos

ition

aft

er

Verti

cal S

pect

rom

eter

(mm

)

As the cavity strength is increased, the momentum change after the exchange line is reduced

1. Change the input momentum (0.70% Increments)2. Measure the vertical offset after exchange line spectrometer3. Increase Deflecting Cavity Strength

12ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Diagnostics for A0 EEX Prior to the exchange :

– OTR screens for beam spot size measurement

– Slits for uncorrelated beam divergence measurement• Combined with above gives a transverse emittance measurement

– Horizontally bending spectrometer for energy and energy spread measurement

– Streak Camera for bunch length

After the exchange:– Same diagnostics for measuring transverse emittance

– Vertically bending spectrometer for momentum spread• Allows us to decouple the momentum spread measurement from any

residual horizontal dispersion from the doglegs

– Martin-Puplett interferometer for bunch length measurement• Also the streak camera (> 1 ps)

13ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Recent Measurements at A0 ( cont’d)A preliminary measurements of several of EEX matrix elements:

Onto an attempt to directly measure the exchange:

x [mm.mrad] z [mm.mrad]

INPUT 6 120

OUT (TM110 OFF) -- 188

OUT (TM110 ON) -- 50.5

Output energy spread measurement

Bunch length measurement with a streak camera.(A. Lumpkin)

TM110 Cavity OFF

TM110 Cavity ON

Resulting emittances values:

Close to CSR increased emittace (R. Fliller)

14ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

ANL-NIU-TsingHua Collaboration For EEX

AWA– Wei Gai (Leader)– Sergey Antipov – Manoel Conde– Felipe Franchini (Tech)– Feng Gao (Student)– Chunguang Jing ( Euclid supported)– Richard Konecny (Super Tech)– Wanming Liu– John Power– Zikri Yusof

APS– Kathy Harkay, (Yin-e Sun), (Alex Lumpkin)

NIU– Philippe Piot– Marwan Rihaoui (GS)

TsingHua– Cavity fabrication

15ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Emittance Exchange (EEX) at the Argonne Wakefield Accelerator

Gun Linac

ICT1 GVGV

TQ1,TQ2,TQ3YAG1 YAG2 Emittance

Exchanger

x=10 my=3 mz= 3 m x= 3 m

y=3 mz= 10 m

TM110

Photoinjector

AWA photoinjector:Q=100pC; K= 12 MeV;Laser: x=y=2.5 mm; z=1.15 ps;

EEX beamline:=15 deg; x = 25 cm; k=4

Overall Goal: exchange small z for

largex with small Q

bunchesN.B. Exchanged many idea with Fermilab Emittance Exchange Group

16ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Diagnostics for AWA EEX ANL diagnostics will be more challenging than A0 due to small

longitudinal emittance, thus short bunch length Spot size

– OTR screens for beam spot size measurement (same as A0)

Beam divergence– pepper pot, (allows us to look at correlations, including x-y for flat beam)

Energy and energy spread before and after EEX: – Spectrometer (same as A0)

Bunch length– zero-crossing method with linac, deflecting cavity (short bunch)

– Exploring EOS ( help from Jinhao Ruan)

In addition:– Time-of-flight monitor: stripline-based phase detection

– Longitudinal phase space: linac phase scan or deflecting cavity + spectrometer

17ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

Cavity fabricated atTsinghua U in Beijing

•Trajectory offset in a deflector cavity•D. Edwards (theory), J. Power (simulation)

•Developed a theory to eliminate by adjust cavity parameters

Deflector Cavity

Deflector cavity arrives from Tsinghua U (soon)

Installation to AWA beamline (Fall, 2008)

Improved Longitudinal Emit Measurement with deflector cavity + Spectrometer

18ANL-UChicago-FNAL Collaboration Meeting, June 27, 2008

NORTH

CONTROL ROOM LASER ROOM

SCALE 1:120

AWA AREA LAYOUT (present to 2010)

WITNESS GUNTEST STAND BEAMLINE

PHOTOCATHODE GUN

PREACCELERATOR(UPGRADED)

TEST SECTON

SPECTROMETER SPECTROMETER

LINAC

GUN

NIU LAB

BEING REMOVED

EEX BEAMLINE

NEW WITNESS BEAM