Addressing material challenges in high-power targetry

Transcription

1 Addressing material challenges in high-power targetry M. Tomut* C.Hubert, C. Trautmann, O. Rosmej, A. Schlüter, Ch. Kuhn, R. Müller, I K Krasyuk, A Yu Semenov, I A Stuchebryukhov, R S Belikov, K V Khishchenko, * GSI, Darmstadt, Germany

2 Outline Radiation- induced target material degradation: swelling thermal diffusivity electrical conductivity hardening- new stress-concentrators damage recovery at high temperature Dynamic response at high strain rates: high power lasers experiments Dynamic response in context of radiation damage Simulations of dynamic thermal fracture of targets in the context of radiation damage 6th High Power Targetry Workshop, 12th April 2016

3 Radiation- induced target material degradation

4 Beam- induced swelling in graphite Swelling mechanism in irradiated graphite; defect creation Swelling measurementsprofilometry Leads to additional stress at the edge of the beam spot on target 6th High Power Targetry Workshop, 12th April 2016

5 Effects of beam- induced degradation of thermal diffusivity of graphite Super-FRS Beam Catchers pristine graphite T max K beam radiation-damaged graphite T max K beam (Ronja Knöbel, Helmut Weick, Super-FRS) Thermal simulation shows cooling problem with radiation-damaged graphite: - degradation of thermal diffusivity: W/(m K) -> 15 W/(m K) 6th High Power Targetry Workshop, 12th April 2016

6 Online monitoring of electrical resistivity degradation ion irradiated graphite exp. set-up IR temp. recording nuclear loss vs. electronic loss de/dx dependence 6

7 Ion beam induced hardening in graphite 4.8 MeV/u Xe U Hardness E modulus Hardness / E modulus Dependence on de/dx 7

8 Failure of graphite exposed to pulsed 238 U beam 238 U, 1.14 GeV; 1.5 x10 10 i/pulse ; 150 µs, 1 Hz 5x10 14 i/cm i/cm i/cm 2 5x10 12 i/cm 2 creep radiation damage swelling stress concentrators + fatigue crack 8

9 How to mitigate radiation damage effects in graphite (production targets and beam catchers materials) Damage recovery by - operation at high temperatures (> 900 ºC) - post-irradiation annealing thermal diffusivity Young modulus DSC defect annealing F. Pellemoine et al., Nucl.Inst.Meth.B, (2015) DOI: /j.nimb C.Hubert et al., Nucl.Inst.Meth.B, (2015) DOI: / j.nimb at T> 900 ºC beneficial effect on recovery of thermo-mechanical properties thermal diffusivity reaches 30 % of the pristine value (1500 ºC) Young modulus reaches pristine value 6th High Power Targetry Workshop, 12th April 2016

10 Dynamic response at high strain rates: high power lasers experiments

11 Spall strength of isotropic graphite at high strain rates- experiments at PHELIX laser at GSI High strain rates induced by laser-driven shock wave Tested materials: graphite & diamond Diagnostic online: - VISAR - X-ray backlighter - X-ray scattering Post-exposure: - Phase transformation - Raman spectroscopy - Profilometry of spall crater

12 Dynamic mechanical response of carbon materials at large strain rates Cu-CD composite Relevant for Future Circular Collider materials Experiment at PHELIX - GSI Quantum Electronics 45 (2015)

13 Dynamic response in context of radiation damage

14 Experimental details Irradiation parameters & set-up Beam parameters 4.8 MeV/u U 28+;; 0.15 ms pulse length; 1 Hz Up to i/cm 2 per pulse Up to fluences of i/cm 2 LDV IR camera 14

15 Vibration of a disc beam modified material in the central beam spot vibration with one circular node pristine sample vibration with two circular nodes modified material in the beam spot vibration with one circular node and one diameter node beam hits eccentric Animation courtesy of Dr. Dan Russell, Grad. Prog. Acoustics, Penn State 15

16 Oscillation monitoring as a function of fluence Polycrystalline isotropic graphite 140 μm Target failure With radiation damage accumulation: Additional reflection at irradiated / non-irradiated interface increase of frecquency increase of damping decrease of velocity 16

17 Measured maximum velocities - LDV Decrease of maximum velocity with accumulated dose: Radiation damage: density reduction in beam spot internal friction plastic deformation processes 17

18 Simulations of dynamic thermal fracture of targets in the context of radiation damage

19 Phase field modelling of brittle fracture induced by pulsed beams Smooth field s approximates cracks Set of coupled PDEs determines deformation, heat transfer and fracturing

20 Fracturing of irradiated graphite cylinders at different beam-spot temperatures

21 Fracturing of irradiated graphite cylinders at different beam-spot temperatures Hoop stress

22 Conclusions and Outlook Experimental work and simulations on dynamic response of irradiated graphite materials to pulsed beam show in general earlier failure in the material that accumulated radiation damage A complex puzzle has to be put together as not all effects of accumulated dose and high beam intensity have a detrimental effect on the target lifetime 6th High Power Targetry Workshop, 12th April 2016

23 Collaborators GSI & TU Darmstadt: C. Hubert, A. Prosvetov, P. Simon, K. Kupka, H. Weick, R. Knobel, O. Rosmej, C. Trautmann, PHELIX laser team University of Kaiserslautern: Alexander Schlüter, Charlotte Kuhn, Ralf Müller General Physics Institute of the Russian Academy of Sciences, Moscow: I K Krasyuk, A Yu Semenov, I A Stuchebryukhov Joint Institute for High Temperatures of the Russian Academy of Sciences: R S Belikov, K V Khishchenko MSU/FRIB: W. Mittig, M. Avilov, F. Pellemoine

24 Too much stress? 6th High Power Targetry Workshop, 12th April 2016