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

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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, , 2006)

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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 D2D3 D4 3.9 GHz TM 110 Diagram by Tim Koeth.

ANL-UChicago-FNAL Collaboration Meeting, June 27, Improve HG X-Ray FEL Performance (P. Emma, Z. Huang, P. Piot, KJK) Electron bunch emittance of current X-ray FEL projects is (  x  y  m  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  z  m FBT: (  x  y,  z  m Exchange x & z  (  x  y,  z  m Q=30 pC,  z =10 fs Higher gain Lower K Lower E-energy

ANL-UChicago-FNAL Collaboration Meeting, June 27, To Obviate Electron Damping Ring from ILC Emittances of ILC electron bunches are (  x  y  z  m These bunches are produced by a 5 GeV, 6 km damping ring The  emittance  T  x  y ) 1/2 is too small for photocathode A possibility: (1, 1, 8)  (50,0.02, 8)  (8, 0.02,50) (Ph. Piot)

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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 data  Tim 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 ANL-FNAL collaboration –Bi-(Tri-) weekly meetings and common web page –Especially productive in exchanging ideas on diagnostics

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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

ANL-UChicago-FNAL Collaboration Meeting, June 27, Use a 3.9GHz, 5 cell copper cavity based on the CKM SRF deflecting cavity cooled with liquid N 2. An 80 kW klystron is available. A0 Photoinjector Layout with EEX beamline EEX at FNAL-A0 Dipoles Vertical Spectrometer 3.9 GHz TM 110 (deflecting mode) Cavity

ANL-UChicago-FNAL Collaboration Meeting, June 27, First Deflected Beam by a CKM type Cavity Operating phase for exchange

ANL-UChicago-FNAL Collaboration Meeting, June 27, Recent Measurements at A0 ( Tim Koeth) TM 110 cavity strength, k o Vary cavity strength record vertical BPM reading Intro  p from 9-Cell OFF73%90%100%105% Vertical Beam Position after Vertical Spectrometer (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 spectrometer 3.Increase Deflecting Cavity Strength

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

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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] INPUT6120 OUT (TM110 OFF)--188 OUT (TM110 ON) 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)

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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

ANL-UChicago-FNAL Collaboration Meeting, June 27, Emittance Exchange (EEX) at the Argonne Wakefield Accelerator GunLinac ICT1 GV TQ1,TQ2,TQ3 YAG1YAG2 Emittance Exchanger  x =10  m  y =3  m  z = 3  m  x = 3  m  y =3  m  z = 10  m TM 110 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 large  x with small Q bunches N.B.  Exchanged many idea with Fermilab Emittance Exchange Group

ANL-UChicago-FNAL Collaboration Meeting, June 27, 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

ANL-UChicago-FNAL Collaboration Meeting, June 27, Cavity fabricated at Tsinghua 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

ANL-UChicago-FNAL Collaboration Meeting, June 27,