Bagnoud, V.

Blazevic, A.

Brabetz, C.

Busold, S.

Deppert, O.

Jahn, D.

Kroll, F.

Roth, Markus

Schumacher, D.

GSI Repository

Upgrade of GSI’s laser-driven ion beamline at Z6∗S. Busold1,2, D. Schumacher1, C. Brabetz1, D. Jahn3, F. Kroll4, O. Deppert3, A. Blazevic1,2,V. Bagnoud1,2, and M. Roth31GSI Helmholtzzentrum fu¨r Schwerionenforschung GmbH, Darmstadt, Germany; 2Helmholtz Institut Jena, Germany;3IKP, TU Darmstadt, Germany; 4Helmholtz-Zentrum Dresden - Rossendorf, GermanyThe LIGHT beamlineThe German national collaboration ”LIGHT” (Laser IonGeneration, Handling and Transport, [1]) has implementeda worldwide unique laser-driven proton beamline at GSI.Compact acceleration up to nearly 30 MeV proton ener-gies is possible from the novel plasma source via the TNSAmechanism, which is driven by the PHELIX 100 TW laserbeam. Therefore, at the Z6 experimental area laser intensi-ties of up to 5×1019 W/cm2 are accessible. A pulsed high-field solenoid then provides for the necessary beam colli-mation and energy selection [2] and typically protons withan energy between 8 and 10 MeV are chosen.Furthermore, a radiofrequency (rf) cavity is implementedat 2 m distance to the source for phase rotation of the cre-ated single bunch, which shows a typical energy spreadof around 20% (FWHM around central energy) and highparticle numbers of up to 109. Energy compression of thebunch below 3% was demonstrated in an experimental runin 2013 [3].solenoid 3 gap cavity quadrupole doubletsFigure 1: Simulation (code: TraceWin) of the 7.8 MeV pro-ton beam size (rms) through the current beamline, from thesource up to a new diagnostic chamber at 6 m.For the 2014 campaign, the beamline has been extended bya diagnostic chamber at 6 m distance to the source, two per-manent magnetic quadrupole doublets (50 mm, 25 T/m) forbeam transport, see figure 1, and an optional third doublet(80 mm, 85 T/m and 45 mm, 105 T/m) for final focusing ofthe bunch. The additional space behind the cavity, whichis again used at -90 deg synchronous phase but this time athigher rf power to ’over-focus’ the bunch in longitudinalphase space, compare figure 2, is necessary as drift space∗This work is supported by the Helmholtz Institute Jena.phase@108.4MHz [deg]rel. energy E-E0 [MeV] rel. energy E-E0 [MeV] 01-101-10-200 200 0-200 200phase@108.4MHz [deg]01rel. particle density01rel. particle densityz=2mcavity inputz=2.55mcavity outputenergy compressionz=2.55mcavity outputphase focusingz=6mtemporal focusf1(Urf)f2(Urf)(a) (b)(c) (d)Figure 2: Simulated longitudinal phase space diagrams forthe two current operation modes when injecting the laseraccelerated proton bunch into the rf cavity at -90 deg syn-chronous phase: energy compression or temporal compres-sion of the bunch along a drift via phase focusing.for phase focusing experiments.Recent results and outlookIn the 2014 campaign, proton bunches with a central energyof 7.8 MeV were selected from the source and propagatedthrough the beamline, containing typically particle num-bers in the range of 2×108 to 5×108 within FWHM. Theirlength could be compressed in time to a FWHM bunchlength of τ=(462±40)ps.The transverse beam profile, however, could be reduced inthe experiment only to a line focus of 3×18 mm2 (FWHM).Therefore, the implementation of a second pulsed solenoidat the end of the beamline is planned as a new steep final fo-cusing system to access highest peak intensities. Also theacceleration of not only protons but also carbon, oxygenand flourine will be explored in 2015.References[1] S. Busold et al., NIMA 740, 94-98 (2014)[2] S. Busold et al., PRSTAB 16, 101302 (2013)[3] S. Busold et al., PRSTAB 17, 031302 (2014)APPA-MML-PP-04 GSI SCIENTIFIC REPORT 2014278 DOI:10.15120/GR-2015-1-APPA-MML-PP-04

Upgrade of GSI's laser-driven ion beamline at Z6

http://repository.gsi.de/record/184009/files/APPA-MML-PP-04.pdf

Upgrade of GSI's laser-driven ion beamline at Z6

Abstract

Similar works

Full text

Available Versions

GSI Repository