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Using the code QP3 to calculate quench thresholds for the MB Arjan Verweij, TE-MPE

Using the code QP3 to calculate quench thresholds for the MB Arjan Verweij, TE-MPE. The code QP3.

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Using the code QP3 to calculate quench thresholds for the MB Arjan Verweij, TE-MPE

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  1. Using the code QP3 to calculate quench thresholds for the MB Arjan Verweij, TE-MPE Verweij, TE-MPE. 19 June 2009, MPP meeting

  2. The code QP3 • The code QP3 can be used for any electrodynamic-thermal calculation of superconductors (or normal conductors), especially suitable for uncoiled conductors or coils with small heat transfer between the turns. • It is used to calculate: • QPS thresholds for busbars/coils. • Quench propagation. • Hot spot temperatures in coils. • The 2008 accident. • The behaviour of defective joints in the 13 kA circuits (‘safe current’, required shunt size for the repair, tests in FRESCA and SM-18). • ….. and can ‘easily’ be used to calculate the quench thresholds for BLM settings. Verweij, TE-MPE. 19 June 2009, MPP meeting

  3. Modeling the geometry Considering the high contact resistance between the strands in a Rutherford cable, the response of the MB cable due to a beam loss stretching over several meters can be modeled by a single strand with a length of half the cable transposition pitch, and symmetry lines at both ends. Verweij, TE-MPE. 19 June 2009, MPP meeting

  4. Variations over the cable width • QP3 takes realistic variations (over half a pitch) of the following parameters: • Field (input from Roxie) • Void volume (input from tomography measurements from TE-MSC) • Cooling surface with helium inside the voids (input from tomography measurements from TE-MSC) • Beam losses (input from Note 422) • Cooling to the helium bath (input from heat transfer measurements at CERN and Saclay on dummy LHC coils). Verweij, TE-MPE. 19 June 2009, MPP meeting

  5. Variations over the cable width Verweij, TE-MPE. 19 June 2009, MPP meeting

  6. The model 1.9 K bath Kapton insulation Conductor sections Voids with helium Thin edge Thick edge 14 x4 mm=56 mm (=pitch/2) An external heat pulse (i.e. beam loss) can be applied with arbitrary shape (both in space and in time). Verweij, TE-MPE. 19 June 2009, MPP meeting

  7. Inputs • Resistivity=f(B, T, RRR) • kCu=f(B, T, RRR) • kkapton=f(T) • CpHe=f(T) • CpCu=f(T) • CpNbTi=f(T,B) • Cooling to helium inside voids: • Transient Kapitza cooling up to Tl or up to maximum heat flow (35000 W/m2), and film boiling afterwards. • Infinite heat flow between the helium in the voids up to Tl and no heat flow above Tl. Steady-state heat transfer from conductor to bath through kapton (to be checked if for single cable or coil) Verweij, TE-MPE. 19 June 2009, MPP meeting

  8. Results Verweij, TE-MPE. 19 June 2009, MPP meeting

  9. Changing some input parameters….. Verweij, TE-MPE. 19 June 2009, MPP meeting

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