Kim, V.

Lamour, E.

Lomonosov, I.

Piriz, A. R.

Rozet, J.

Stöhlker, T.

Tahir, N. A.

Vernhet, D.

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Thermal simulations of a C beam stripper for experiments at Spiral2∗N.A. Tahir1, V. Kim2, E. Lamour3, I.V. Lomonosov2, A.R. Piriz4, J.P. Rozet3, Th. Sto¨hlker5, andD. Vernhet31GSI, Darmstadt, Germany; 2IPCP, Chernogolovka, Russia; 3Institut des NanoSciences de Paris,UMRCNRS–Universite´ Pierre et Marie Curie, Paris, France; 4UCLM, Ciudad Real, Spain; 5GSI, Darmstadt, Germany; IOQ,Friedrich-Schiller-Universitt, 07743 Jena, Germany; Helmholtz-Institut Jena, 07743 Jena, GermanyWe present 3D thermal simulations (excluding hydrody-namics) of a wheel shaped beam stripper made of solid Cthat has been designed for use in the FISIC (Fast Ion-SlowIon Collision) experiments at the SPIRAL2 facility. Theinner radius, R1 of the target is 32 cm, the outer radius,R2 is 35 cm while the beam is perpendicular to the targetsurface at a radius, R0 = 33 cm (see Fig. 1). The target isrotated at a rate of 2000 rpm. Several ion species includingFigure 1: Stripper geometry.Ne, Ar and Ni, with the following beam parameters, havebeen considered. The transverse ion beam intensity dis-tribution in the focal spot is assumed to be Gaussian withσ = 0.5 mm corresponding to the most extreme case. At theexit of the LINAC, the beam comprises of particle bunches,each bunch having a duration of 1 ns while the bunch fre-quency is 88 MHz that leads to a separation of 10.36 nsbetween two neighboring bunches.Detailed simulations have been done for the followingsets of beam and target parameters.Case 1: Ne7+ with E = 5 MeV/u, I = 10 pµA andN = 6.25x1013/s. Two different target thicknesses, namely,13 and 100 µg/cm2, respectively, have been considered.Case 2: Ar13+ (a) with E = 4 MeV/u, I = 10 pµA andN = 6.25x1013/s. Three different target thicknesses includ-ing, 4.4, 20 and 320 µg/cm2, respectively, have been used.(b) with E = 14 MeV/u, while using four different targetthicknesses, namely, 9.5, 32, 105 and 750 µg/cm2.Case 3: Ni18+ (a) with E = 10 MeV/u, I = 1 pµA andN = 6.25x1012/s. Five different target thicknesses includ-ing, 34, 60, 80 190 and 1300 µg/cm2, respectively, havebeen considered.(b) with E = 14 MeV/u, again using five different tar-get thicknesses, namely, 42, 60, 95, 200 and 1450 µg/cm2,respectively.∗Work supported by the BMBFThese simulations have been performed using a 3D com-puter code PIC3D [1] which includes ion energy deposi-tion, heat conduction and thermal radiation losses. Twodifferent values of the emissivity, ǫ, namely, 0.2 and 0.8,have been used to check the influence of emissivity on tar-get cooling. 300 350 400 450 500 550 600 650 700 750 800 0  0.5  1  1.5  2  2.5T (K)t (s)Figure 2: Temperature vs time at R0 (top curve), R1 (mid-dle) and R2 (lowest); red curves (ǫ = 0.2), blue curves(ǫ = 0.8); Ar13+, E = 4 MeV/u, I = 10 pµA and target thick-ness = 320 µg/cm2. 300 350 400 450 500 0  2  4  6  8  10  12  14T (K)t (s)Figure 3: Same parameters as in Fig. 2, but usingNi18+, E = 10 MeV/u, I = 1 pµA and target thick-ness = 1300 µg/cm2.It is seen in Figs. 2 and 3 that the temperature at thecenter of the focal spot remains safely below the sublima-tion temperature of C. However, the possibility of materialdamage due to thermal stresses needs to be addressed. Thiswork is in progress.References[1] V.E. Fortov et al., Intnl. J. Impact Eng. 33 (2006) 244.APPA-MML-AP-31 GSI SCIENTIFIC REPORT 2014246 DOI:10.15120/GR-2015-1-APPA-MML-AP-31

Thermal simulations of a C beam stripper for experiments at Spiral2

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Thermal simulations of a C beam stripper for experiments at Spiral2

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