Acceleration of Heavy Ion Beams with a Superconducting Continous Wave cw-Linac at GSI W. Barth 1,2 , K. Aulenbacher 1,2,3 , M. Basten 4 , M. Busch 4 , C. Burandt 1,2 , F. Dziuba 1,2,3 , V. Gettmann 1,2 , M. Heilmann 2 , T. Kürzeder 1,2 , S. Lauber 1,2,3 , J. List 1,2,3 ,M. Miski-Oglu 1,2 , H. Podlech 4 , A. Rubin 2 , A. Schnase 2 , M. Schwarz 4 , S. Yaramyshev 2 1 Helmholtz Institut Mainz, Germany 2 GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany 3 Johannes Gutenberg-Universität Mainz, Mainz, Germany 4 IAP Goethe-Universität Frankfurt, Frankfurt, Germany 1. Introduction 2. General Linac layout and RF-cavity development 3. EQUUS beam dynamics and Matching section 4. Acceleration of heavy ion beams - First beam test with a sc CH-cavity - Systematic phase space measurements 5. Further R&D/Advanced Demonstrator Project HELIAC* – preparation work 6. 7. Outlook * HElmoltz LInear ACcelerator
Introduction GSI UNIversal Linear ACcelerator High Charge State Injector (1991) Single Gap Resonators High Current Injector Alvarez (1975) (1975) (1999) 2 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
Uranium High Current Injector-Performance 16 Oct 14 U 28+ Nov.14 Oct 15 12 July 16 ion current [emA] Design/1999 Design/FAIR 8 U 4+ 4 0 LEBT HSI gas stripper 3 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
GSI/FAIR-Requirements FAIR high beam currents low repetition rate (max. 3 Hz) low duty factor (0.1 %, pulse length for SIS18 only 100 µs) Super Heavy Element-user program relatively low beam currents high repetition rate (50 Hz) high duty factor (100 %, pulse length up to 20 ms) Material Science at GSI-experimental hall Heavy Ions (m 200) High Beam Energy (up to 10 MeV/u) Continuous Beam Energy Variation (1.5 – 10 MeV/u) 4 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
cw-LINAC-project: Motivation Nuclear reactions at the Coulomb-barrier production of Super Heavy Elements (SHE) 288 289 Production of Element , , 30 𝑓𝑤𝑓𝑜𝑢𝑡 uut uut 115 115 (D. Rudolph, Lund Univ., PRL 111, 112502 (2013)) GSI- Unilac cw-Linac 6 ∙ 10 12 6 ∙ 10 13 Beam intensity (particle/s) Beam on target 3 weeks 2 days 5 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
General Heavy Ion cw-Linac layout 6 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
H-type Cavity developments HSI 36 MHz@gsi sc-prototype, 360 MHz HLI 108 MHz@gsi nc-CH-cavity sc-booster cavity, 325 MHz rt-325 MHz IH 216 MHz@HIT/Heidelberg Alvarez Wideröe 7 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
CH-cavity: Field profiles H field E field E field along beam axis - - + + - + 1,4 Simulation 1,2 Measurement 01-28-2015 1,0 E / arb. units - - - + + + 0,8 - - + + 0,6 0,4 0,2 - - - + + + 0,0 0 100 200 300 400 500 600 700 Beam axis / mm • Multigap drift tube cavity for the acceleration of protons and ions in the low and medium energy range • Drift tubes are alternating connected to “ + ” and “ - ” potential C ross-bar- H -mode cavity CH cavity • Equidistant drift tubes length special beam dynamics • 8 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
EQUUS beam dynamics concept courtesy: F. Dziuba et al., Poster@LINAC2018, THPO073 Longitudinal motion of an accelerated bunch in the constant- β -section EQUUS - EQUidistant mUltigap Structure y m y o 0.01 3 Particles too early obtain less acceleration Db 1 0 2 longitudinal focussing 1 -0.01 y (deg) 0 -90 -180 -270 2 Particles synchr. reach max. acceleration 7 longitudinal defocussing 3 2 E o (MV/m) 1 0 b s Particles too early obtain less acceleration 3 -7 y (deg) longitudinal focussing -270 0 -90 -180 Resonant acceleration at = -30 EQUUS 1 3 2 9 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
RF Testing of the CH-Cavity (10/2016) RF test in a horizontal cryostat (@4.2 K) Dynamic tuner Static tuner Inclined stem courtesy: F. Dziuba et al., Poster@LINAC2018, THPO073 Preparation ports Helium vessel • Improved performance (add. HPR) • Low field emission rate • High field gradient • Therm. quenching beyond 9.6 MV/m 10 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
Experimental setup of the demonstrator at GSI Layout of the horizontal cryomodule Matching line - demonstrator – test bench Superconducting • Steering magnets • Phase probes for TOF measurement 9.3 T solenoids • Rebuncher • Beam current transformers • Quadrupole doublet • Bunch shape monitor (Feschenko) • Profile grids • Emittance measurement Demonstrator at GSI-High Charge State Injector (HLI) Superconducting 217 MHz CH cavity Support frame LHe reservoir (3000 l) 11 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
12 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
Matching the cw-Linac Demonstrator courtesy: A. Rubin, Proc of IPAC'13 13 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
Longitudinal matching QD QT QD B Mob HLI cw R R P G T T P P S x | y 1,4 MeV/u 1 2 Demonstrator EMI M D (z) D (z) 14 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
First Acceleration QD QD QT B Mob HLI cw R R P G T T P P S x | y 1,4 MeV/u 1 2 Demonstrator EMI M Intensity [arb. units] Intensity [arb. units] • Measurement of transient signal induced by traveling bunch • Acceleration! Energy gain of 0.5 MeV/u systematic scan of rf- • phase and amplitude t [ns] 15 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
Bunch structure measurement QD QD QT B Mob HLI cw R R P G T T P P S x | y 1,4 MeV/u 1 2 Demonstrator EMI M D (z) cavities off R1 + R2 R1 + R2 + CH0 16 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
RF-parameter (matched case) 17 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
Amplituden-scan 100 2,3 75 Beam Transmission [%] 2 W kin [MeV/u] 50 1,7 E acc [MV/m] 25 Eacc [MV/m] 1,4 Transmission 1,1 0 0 1 2 3 4 5 6 E acc [MV/m] W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019 18
Systematic Scans (RF-phase/-amplitude) Ar 9+ Ar 9+ 2,0 100 Beam Transmission [%] 80 Wkin [MeV/u] 1,8 60 40 1,6 20 1,4 0 160 4.6 160 4.6 210 210 3.9 3.9 260 260 310 3.0 3.0 310 3.0 3.5 3.9 4.3 4.6 3.0 3.5 3.9 4.3 4.6 Ar 6+ 5.5 MV/m W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019 19
Emittance measurement horizontal vertical 1.40 MeV/u Ion species: 40 Ar 11+ , 40 Ar 9+ , 40 Ar 6+ (A/q=6.7), 50 Hz, 5ms, 25% beam duty, cw (rf duty), 1.5pµA (particle current), 95% (beam transmission), 0.460 MeV/u ( D W), transv. emittance growth 12% horizontal vertical 1.86 MeV/u W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019 20
Advanced Demonstrator Standard cryomodule layout • New cryo module layout containing demonstrator CH cavity, 2 short CH cavities, 1 buncher and 2 solenoids • Simplified cavity design (easier manufacturing & surface processing) • CH1 & CH2 are already in production (delivery at 4 th quarter of 2019) • Ordering of cryostat at 1 rd quarter of 2019 • Tendering process for rebuncher, solenoids, rf-amplifiers and high power couplers ongoing Moderate increase of design gradient more compact linac design or higher A/q • 21 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
First RF-measurement for CH1 in a vertical cryostat 8 gap-CH-cavity courtesy: M. Basten et al., Poster@LINAC2018, THPO072 & SPWR010 22 W. Barth, "Acceleration of Heavy Ion Beams with a Superconducting cw-Linac at GSI", GSI-Acc. Seminar, April/11/2019
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