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SNS Wire Scanner Preliminary Design Review

SNS Wire Scanner Preliminary Design Review. Heating Calculations. By C.J. Liaw, BNL July 24, 2002. Wire Heating in the HEBT. Carbon wire size: 32 m m dia. Beam parameters: *1 GeV H - beam, Gaussian Distributed *1 MW~ 2 MW, 60 Hz, 1 ms long

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SNS Wire Scanner Preliminary Design Review

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  1. SNS Wire Scanner Preliminary Design Review Heating Calculations By C.J. Liaw, BNL July 24, 2002

  2. Wire Heating in the HEBT Carbon wire size: 32 mm dia. Beam parameters: *1 GeV H- beam, Gaussian Distributed *1 MW~ 2 MW, 60 Hz, 1 ms long * Beam current, I = 16 ~ 32 mA over a pulse Min. beam size: 1.4 mm x 1.4 mm ( sx x sy) Mean wire thk.:x= pd/4 =.0025 [cm] Power deposition: P= [(1/r dE/dx)p+ 2*(1/r dE/dx)e] rx* Imax/2psxsy [W/m2] Heating efficiency: h =.82

  3. Wire Heating in the Ring Carbon wire size: 32 mm dia. Beam parameters: *1 GeV, 1 ~ 2 MW, 60 Hz proton beam *Injected 1000 bunches in 1 ms before extraction * Beam current, I = from 0 to 16 A in 1 ms (1 MW case) = from 0 to 32 A in 1 ms (2 MW case) Eff. beam size: A=6.45 x 10-6+3.09 *t [m2], where t =time [sec] Mean wire thk.:x= pd/4 =.0025 [cm] Power deposition: P= (1/r dE/dx)*rx* (Imax*t/1x10-3)/A = 1.27 x 108(t/A) [W/m2] (for 1 MW case) = 2.54 x 108(t/A) [W/m2] (for 2 MW case) Heating efficiency: h =.82

  4. Wire Heating in the RTBT Carbon wire size: 32 mm dia. Beam parameters: *1 GeV proton beam, quasi-uniform distributed *1~ 2 MW, 60 Hz, 695 ns long * Ave. beam current, I = 23 A over a pulse (1 MW case) = 46 A over a pulse (2 MW case) * Max. beam current, Imax = I *1.25 Min. beam size: 56 mm x 68 mm ( H x V) Mean wire thk.:x= pd/4 =.0025 [cm] Power deposition: P= (1/r dE/dx)prx* Imax/ (H*V) [W/m2] Heating efficiency: h =.82

  5. Governing Equation dT/dt = 4(rpdc)(Ph-pse(T4-T04))  where T = wire temperature [K] To = beam pipe temperature = 297 [K] d = diameter of the wire [m] t = time [sec] h= heating efficiency s = Stefan Boltzmann constant = 5.67 x 10-8 [W/m2K4] r = density =2000 kg/m3 e= emissivity =0.8

  6. Heat Capacity of Carbon Material

  7. Maximum Wire temperature in the HEBT, the Ring, and the RTBT (One MW Case)

  8. Maximum Wire temperature in the HEBT, the Ring, and the RTBT (Two MW Case)

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