Al Omari, H.

Bagnoud, V.

Blazevic, A.

Brabetz, C.

Busold, S.

Deppert, O.

Hofmann, I.

Joost, M.

Kroll, F.

Roth, M.

Schumacher, D.

Zielbauer, B.

GSI Repository

Transport and focusing of laser-accelerated protons at Z6∗S. Busold1, D. Schumacher4, O. Deppert1, C. Brabetz2, F. Kroll3, M. Joost3, H. Al Omari2,A. Blazevic4,5, B. Zielbauer4,5, V. Bagnoud4,5, I. Hofmann4,5, and M. Roth11TU Darmstadt, IKP, Germany; 2JWG Universita¨t Frankfurt, IAP, Germany; 3Helmholtzzentrum Dresden-Rossendorf,Germany; 4GSI, Darmstadt, Germany; 5Helmholtz Institut Jena, GermanyLIGHTIrradiation of µm-thin foils with high-intensity laserpulses (> 1019 W/cm2) became a reliable tool during thelast decade for producing high-intensity proton bunches,providing up to 1014 protons in about a pico-second from asub-millimeter source. However, the proton energy distri-bution is of an exponential shape with a currently achiev-able cut-off energy < 100MeV (TNSA mechanism) andthe beam is highly divergent with an energy-dependentenvelope-divergence of up to 60 degrees. Thus, for mostpossible applications it is necessary to be able to cap-ture and control these protons as well as select a specificenergy. Therefore, the LIGHT collaboration (Laser IonGeneration, Handling and Transport) was formed, dedi-cated to investigate the possibilities of compact laser-drivenion sources for ions in the multi-MeV range. In this con-text, a lot of preperative work had been done at GSI inthe last years and the most promising results could be ob-tained with small quadrupol magnets [1] and pulsed high-field solenoids [2, 3]. And since the commissioning of thePHELIX 100 TW beamline [4] some experiments could al-ready move to the Z6 area, where now short-pulse lasertechnology and conventional accelerator infrastructure canbe merged in a unique way.pulsed high-field solenoidThe first experiment in 2012 for transport and focusingof laser-accelerated protons was done at the Z6 area, wherePHELIX can deliver about 15 J of laser energy on target,exceeding 1019 W/cm2. While the laser hits the front of thetarget, a 5–10µm thin metal foil, the protons are acceler-ated targetnormal from the back side. The pulsed solenoid,placed 80 mm behind the target, is 150 mm long, has anopen aperture of 40.5 mm diameter and can reach a maxi-mum field of 10 T.The magnetic field was adjusted to focus 4.5 MeV pro-tons at 695 mm behind the solenoid (925 mm behind thetarget). The Detection of the proton beam in front of thesolenoid and directly behind (still inside the targetcham-ber) showed the expected energy-dependet focusing andbeam rotation. A proton focus could be reached inside the∗This work is supported by the Helmholtz Institute Jena and HIC forFAIR.x [mm]y [mm]transverse proton focus profile  6.25 12.5 18.75 256.2512.518.7525.0Figure 1: Transverse focus profile of 4.5 MeV protons atnearly 1 m from source, produced with the pulsed high-field solenoid.attached Z6 ion beamline at 695 mm behind the solenoid,containing 5 × 108 particles and with a spot size of 3 mm(FWHM).The results are in good agreement with accompanyingsimulation studies, which are performed with CST particlestudio and TraceWin.permanent-magnetic quadrupole tripletIn a second experimental campaign in 2012, the trans-port and focusing of laser-accelerated protons could betested in the PHELIX laserbay with a permanent-magneticquadrupole triplet. Here, intensities of 5 × 1019 W/cm2were used with about 60 J laser energy on target; i.e. moreparticles are produced initially.A sub-aperture of the full beam (40 mrad divergence)was transported through the triplet and at 630 mm distanceto the source, 10 MeV protons were focused in a 3x6 mm(FWHM) spot size, containing up to 109 particles.References[1] M. Schollmeier et al., PRL 101, 055004 (2008)[2] K. Harres et al., Phys. Plas. 17, 023107 (2010)[3] T. Burris-Mog et al., PRSTAB 14, 121301 (2011)[4] S. Busold et al., GSI scientific report (2011)PNI-IONS-EXP-24 GSI SCIENTIFIC REPORT 2012332

Transport and focusing of laser-accelerated protons at Z6

http://repository.gsi.de/record/52226/files/PNI-IONS-EXP-24.pdf

Transport and focusing of laser-accelerated protons at Z6

Abstract

Similar works

Full text

Available Versions

GSI Repository