Damage to optics under irradiations with the intense EUV FEL pulses

Damage to optics under irradiations with the intense EUV FEL pulses Ryszard Sobierajski 1, Eric Louis 2 1 Institute of Physics PAS, 2 Universiteit Twente

Damage to optics - motivation Properties of the intense FEL beam create, apart new experimental opportunities, extreme demands to optical elements applied in the experimental equipment. Amongst the most serious issues is radiation load imposed on of optics / detectors / samples. C. David et al. Scientific Reports Vol. 1, (2011) 2014 Source Workshop, Dublin 2

intensity [W/cm 2 or J/cm 2 ] e - relaxation energy transport by e - & e - -phonon coupling & phase transisions Fast atomic movements (fast diffusion) Energy transport by phonons (heat diffusion) Thermoelastic processes Characteristic times & processes R/T/A 1 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 3

intensity [W/cm 2 or J/cm 2 ] Characteristic times & processes 1 R/T/A 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 4

Intensity-dependent changes of optical properties single shot optics Detector mirror Particle-coated membrane Si/C ML Incident beam Si/Mo SiC/Mg @ λ = 13.5 nm @ λ = 32 nm C/Co Hau-Riege @ SPIE conference, 2007 CCD @ λ = 6 nm Backing multilayer mirror S.Hau-Riege, R.Sobierajski, PRL 98, 145502 (2007) 2014 Source Workshop, Dublin 5

intensity [W/cm 2 or J/cm 2 ] e - relaxation energy transport by e - & e - -phonon coupling & phase transisions Characteristic times & processes R/T/A 1 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 6

Phase transitions (s-s & s-l) Graphitisation of a-c @ T i ~1050 K, ion~2,5% Melting of c-si @ T i ~1650 K AFM SPEM, ESCA, Triest *J. Gaudin et al., Physical Review B 86 p.024103 (2012) *N. Stojanovic et al., Appl. Phys. Lett. Vol. 89, s.241909, (2006) 2014 Source Workshop, Dublin 7

Thin (a-c) layers on gratings Energy distribution absorbed in the grating *J. Gaudin et al., Opt. Lett 37 p.2022 (2012) Simulations of the X-ray intensity distribution based on solution of the Helmholtz equation EXTATIC workshop 2014, 21.10.2014 8

intensity [W/cm 2 or J/cm 2 ] e - relaxation energy transport by e - & e - -phonon coupling & phase transisions Fast atomic movements (fast diffusion) Characteristic times & processes R/T/A 1 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 9

Atomic diffusion in multilayer Mo/Si coating (hv ~92eV) 481w.tif @ -10.0 [ps] 1.5 1.4 1.3 1.2 1.1 1 Outside crater inside crater Compaction & crystallites formation 2014 Source Workshop, Dublin 10

energy density [a.u.] a-si heat melting transport solid heat release Single shot damage in Mo/Si ML - model 350 300 250 200 150 100 50 h = 91.9 [ev] a-si Mo average over a BL T=T melt level 0 0 10 20 30 40 50 depth [nm] A.R. Khorsand, R. Sobierajski,et al. Optics Express 18, s.700 (2010) Damaging mechanism identified: energy absorption energy diffusion transfers heat from Mo layers to a-si melting of Si layers enables fast diffusion of Mo atoms into Si self-sustained reaction due to reaction heat release period compaction for bilayers with melted a-si crater formation 2014 Source Workshop, Dublin 11

intensity [W/cm 2 or J/cm 2 ] e - relaxation energy transport by e - & e - -phonon coupling & phase transisions Fast atomic movements (fast diffusion) Energy transport by phonons (heat diffusion) Characteristic times & processes R/T/A 1 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 12

Temperature at the surface [K] Energy densiy U-U 0 [J/m 3 ] Heat diffusion by phonons & heat accumulation 299.6 299.4 surface bottom 299.2 299 298.8 298.6 298.4 298.2 298 297.8 10-12 10-10 10-8 10-6 time [s] 299.6 299.4 299.2 Si substrate 500 microns thick F~100 nj/cm 2 λ=13.5 nm normal incidence L abs ~500 nm 299 298.8 298.6 298.4 298.2 298 10-12 10-10 10-8 10-6 time [s] 2014 Source Workshop, Dublin 13

Heat accumulation effects - melting C. David et al. Scientific Reports Vol. 1, (2011) 2014 Source Workshop, Dublin 14

intensity [W/cm 2 or J/cm 2 ] e - relaxation energy transport by e - & e - -phonon coupling & phase transisions Fast atomic movements (fast diffusion) Energy transport by phonons (heat diffusion) Thermoelastic processes Characteristic times & processes R/T/A 1 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 15

deformation [um] Heat load distribution on first mirror SASE1 @ Eu-XFEL 17.5 GeV, 13500 pulses per second average heat load after pulse trains Slide courtesy H.Sinn from X-ray optics CDR on xfel.eu (2011) 2.00E-02 1.80E-02 2.2 nm 1.60E-02 1.40E-02 FEL Compto n (400 kev) Cooling in this model: clamping from both sides 1.20E-02 1.00E-02 8.00E-03 6.00E-03 4.00E-03 2.00E-03 after pules train average after pulse train 16 nm average 0.00E+00 0 100 200 300 400 500 600 700 800 mirror length [mm] 2014 Source Workshop, Dublin 16 FEA by Antje Trapp (2011)

Time-resolved studies of the deformations D.D.Ryutov Rev. Sci. Instr. 74 (2003) *J. Gaudin et al., Opt. Exp. 19 p.15516 (2011) 2014 Source Workshop, Dublin 17

intensity [W/cm 2 or J/cm 2 ] e - relaxation energy transport by e - & e - -phonon coupling & phase transisions Fast atomic movements (fast diffusion) Energy transport by phonons (heat diffusion) Thermoelastic processes Beyond ms time scale R/T/A 1 0.8 0.6 0.4 0.2 0 10-14 10-12 10-10 10-8 10-6 10-4 time [s] 2014 Source Workshop, Dublin 18

Period change (nm) Atomic diffusion induced silicide formation High res. Cu-K a reflectance, 10h @ 250C 1 2-0.05 Dd -0.10 200 o C 3 4-0.15 225 o C 250 o C -0.20 275 o C Bragg law: 2 m 2dsin m 1 sin 2 Growth of high density Mo X Si Y interfaces causes reduction of multilayer period m 0 20 40 60 Annealing time (h) Si Mo Si d T,t Dd Si Mo Si MoSi MoSi

Wavelength change(nm) Period change (nm) Thermally stable multilayer With barriers 250 C annealing (hours) Si Mo Si Mo Si Mo Barrier Barrier Barrier Barrier Barrier Barrier 0.10 0.08 No barriers 0.06 0.04 0.02 0.00 0.0 0.5 1.0 1.5 2.0 Years(!) at enhanced temperature 2014 Source Workshop, Dublin 20

Standard damage processes Surface contamination @ FLASH 2014 Source Workshop, Dublin 21

IP PAS: R. Sobierajski, P. Dłużewski, M. Jurek, M. Klepka, D.Klinger, J.B. Pelka, W. Szuszkiewicz, D.Żymierska WUT: D.Sobota, W. Wierzchowski, T. Płociński IP ASCR: L. Juha, J. Chalupsky, V.Hajkova, T. Burian HASYLAB: N. Stojanovic, K. Tiedtke S. Toleikis H. Wabnitz Uni. Essen: K. Sokolowski-Tinten, SLAC: J. Krzywinski, J. Bozek, M. Messerschmidt LLNL: S. Hau-Riege, R. London XFEL: J. Gaudin, H.Sinn FOM: R.A. Loch, E. Louis, S. Bruijn, A.R. Khorsand, R.W. E. van de Kruijs, SPRING-8: M.Yabashi, M.Nagasono This work has been partially supported by the Polish National Science Center (Grant No. DEC-2011/03/B/ST3/02453)