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

Advanced Accelerator R&D: Flat Beam Transform & Emittance ExchangeKwang-Je Kim ANL & U of CJune 27, 2008 ANL-UChicago-FNAL Collaboration Meeting at Fermilab

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

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

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


Flat Beam TransformProduce angular-momentum dominated beam and remove correlationR. Brinkmann, Y. Derbenev, and K. Floettmann (1999, 2001)Experimentally demonstrated at A0D. 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)


Emittance Exchange SchemeFirst 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.Diagram by Tim Koeth.


Improve HG X-Ray FEL Performance(P. Emma, Z. Huang, P. Piot, KJK)Electron bunch emittance of current X-ray FEL projects is (ex, ey)=(1, 1) mm with 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 ez=0.1 mmFBT: (ex, ey, ez)=(10, 0.1, 0.1) mm Exchange x & z (ex, ey, ez)=(0.1, 0.1, 10) mm Q=30 pC, sz=10 fs Higher gain Lower K Lower E-energy


To Obviate Electron Damping Ring from ILCEmittances of ILC electron bunches are (ex, ey, ez)=(8, 0.02, 3000) mmThese bunches are produced by a 5 GeV, 6 km damping ringThe emittance eT= (ex ey)1/2 is too small for photocathodeA possibility: (1, 1, 8)(50,0.02, 8)(8, 0.02,50) (Ph. Piot)


EEX Demonstration ExperimentFNAL/A0Initiated by Helen Edwards, December, 2006, and T. Koeth engaged(ex, ey, ez): (6, 6, 120)(120, 6, 6)mm, Q=1 nCUse CKM cavity design and existing RF powerExciting dataTim will be able to graduate!ANL/AWA-NIU-TsingHua UArgone Acclerator Institute activity, funded by LDRD(ex, ey, ez): (10,3, 3)(3,3,10)mm , Q=0.1 nCNIU (Marwan Rihauoi, GS) and Tsinghua U (defl. cavity)To be finished by 2010-2011ANL-FNAL collaborationBi-(Tri-) weekly meetings and common web pageEspecially productive in exchanging ideas on diagnostics


A0 PeopleHelen Edwards The BossDon EdwardsRay Fliller (The Manager) Yin-e Sun (Recently from ANL)Jinhao Ruan Laser, All things opticalJamie Santucci OperationsTim Koeth Rutgers Ph.D. StudentArtur Paytan Yerevan U. Ph.D. StudentMike Davidsaver UIUC staff, controlsGrigory Kazakevich Guest Scientist, OTRIManfred Wendt Instrumentation, BPMsRandy Thurman-Keup Instrumentation, InterferometerVic Scarpine Instrumentation, OTR and camerasAlex Lumpkin Instrumentation, Radiation Diagnostics (On leave from ANL)Ron Rechenmacher CD, controlsLucciano Piccoli CD, controlsGustavo Cancelo CD, Low Level RFWade Muranyi Mechanical Support, Lead Tech.Many Others from AD/RF, AD/MS


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-A0DipolesVertical Spectrometer3.9 GHz TM110 (deflecting mode) Cavity


First Deflected Beam by a CKM type CavityOperating phase for exchange


Recent Measurements at A0( Tim Koeth)TM110 cavity strength, koVary cavity strengthrecord vertical BPM readingIntro dp from 9-CellOFF73%90%100%105%Vertical Beam Position after Vertical Spectrometer (mm)As the cavity strength is increased, the momentum change after the exchange line is reducedChange the input momentum (0.70% Increments)Measure the vertical offset after exchange line spectrometerIncrease Deflecting Cavity Strength


Diagnostics for A0 EEXPrior to the exchange :OTR screens for beam spot size measurementSlits for uncorrelated beam divergence measurementCombined with above gives a transverse emittance measurementHorizontally bending spectrometer for energy and energy spread measurementStreak Camera for bunch lengthAfter the exchange:Same diagnostics for measuring transverse emittanceVertically bending spectrometer for momentum spreadAllows us to decouple the momentum spread measurement from any residual horizontal dispersion from the doglegsMartin-Puplett interferometer for bunch length measurementAlso the streak camera (> 1 ps)


Recent Measurements at A0 ( contd)A preliminary measurements of several of EEX matrix elements:Onto an attempt to directly measure the exchange: Output energy spread measurementBunch length measurement with a streak camera.(A. Lumpkin)TM110 Cavity OFFTM110 Cavity ONResulting emittances values:Close to CSR increased emittace (R. Fliller)

ex [mm.mrad]ez [mm.mrad]INPUT6120OUT (TM110 OFF)--188OUT (TM110 ON)--50.5


ANL-NIU-TsingHua Collaboration For EEXAWAWei Gai (Leader)Sergey Antipov Manoel CondeFelipe Franchini (Tech)Feng Gao (Student)Chunguang Jing ( Euclid supported)Richard Konecny (Super Tech)Wanming LiuJohn PowerZikri YusofAPSKathy Harkay, (Yin-e Sun), (Alex Lumpkin)NIUPhilippe PiotMarwan Rihaoui (GS)TsingHuaCavity fabrication


Emittance Exchange (EEX) at the Argonne Wakefield AcceleratorGunLinacICT1GVGVTQ1,TQ2,TQ3YAG1YAG2Emittance Exchangerex=10 mmey=3 mmez= 3 mmex= 3 mmey=3 mmez= 10 mmTM110PhotoinjectorAWA photoinjector:Q=100pC; K= 12 MeV;Laser: sx=sy=2.5 mm; sz=1.15 ps;EEX beamline:Q=15 deg; hx = 25 cm; k=4Overall Goal: exchange small ez for large ex with small Q bunchesN.B. Exchanged many idea with Fermilab Emittance Exchange Group


Diagnostics for AWA EEXANL diagnostics will be more challenging than A0 due to small longitudinal emittance, thus short bunch lengthSpot sizeOTR screens for beam spot size measurement (same as A0)Beam divergencepepper 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


Deflector CavityCavity fabricated atTsinghua U in BeijingTrajectory offset in a deflector cavityD. Edwards (theory), J. Power (simulation)Developed a theory to eliminate by adjust cavity parametersDeflector cavity arrives from Tsinghua U (soon)

Installation to AWA beamline (Fall, 2008)

Improved Longitudinal Emit Measurement with deflector cavity + Spectrometer


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

Documents

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