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Stress in spherically dished tungsten discs. Goran Skoro 10 July 2008. R.Bennett :
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Stress in spherically dished tungsten discs Goran Skoro 10 July 2008
R.Bennett: We could make a “solid target” from thin foil discs which would effectively have a lower density whilst not decreasing the yield. In addition the beam dissipation would decrease with density. This would make it easier to remove the heat - and it would be simple to increase the surface emissivity from 0.3 to 0.7 further reducing the temperature. As a result we could have a smaller target diameter – say 1 cm – if this increased the yield. The thin disc target would not suffer from axial shock until much higher power dissipations than the solid target. In addition the radial shock can be reduced by spherically dishing the discs (I think?). So again shock is decreased. Goran, do you think you could simulate the shock in a 1 cm diameter disc, 10 micron thick, spherically dished on a 1 cm radius and a 5 cm radius (try these two radii in case it is improved at the smaller radius)? Idea Geometry: 1 cm diameter, 10 micron thick disc spherically dished on a 1 cm radius spherically dished on a 5 cm radius
Neutrino Factory target Tungsten; 1cm diameter, 25 cm length Beam energy = 10 GeV Beam power = 4 MW Rep. Rate = 50 Hz Parabolic beam, r_beam = r_target Optimal beam pulse length 3 x 2 ns bunches energy deposition from MARS B = 20 T “Study II like” scenario “MERIT like” scenario “Best yield” scenario ~ 600 K at the centreline ~ 200 K at the surface Temperature rise per pulse in 1cm diameter target Input for LS-DYNA
Peak Von Mises Stress ~ 2000 MPa !!! LS-DYNA Results: Von Mises stress and ‘deformations’ 1 cm diameter, 10 micron thick tungsten disc spherically dished on a 5 cm radius Time t = 0 Time Time t = 100 us
Time Time Peak Von Mises Stress ~ 2000 MPa !!! Time LS-DYNA Results: Von Mises stress and ‘deformations’ 1 cm diameter, 10 micron thick tungsten disc spherically dished on a 1 cm radius t = 0 t = 100 us
1 cm diameter disc: impossible!!! (Stress too big) 2 cm diameter disc: looks possible Peak Von Mises stress ~ 300 MPa (as in 2 cm diameter tungsten cylinder) … and disc oscillations are not so ‘dramatic’ Conclusions 2 cm diameter, 10 micron thick disc spherically dished on a 5 cm radius BUT…