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Large spread in measured D T (10 – 40 deg)

Large spread in measured D T (10 – 40 deg). Take worst case. MKI.D5R8.B2:TEMP_MAGNET_DOWN. Analysis of heating. Took all fills (to end September) where in stable beams for longer than 10 h Considered only time from top of ramp onwards

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Large spread in measured D T (10 – 40 deg)

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  1. Large spread in measured DT (10 – 40 deg)

  2. Take worst case MKI.D5R8.B2:TEMP_MAGNET_DOWN

  3. Analysis of heating • Took all fills (to end September) where in stable beams for longer than 10 h • Considered only time from top of ramp onwards • Used number of bunches, average bunch current and bunch length as inputs • Fitted initial heating rate (~linear) over first 2 hours

  4. Analysis (to end September)

  5. Dependencies

  6. Can we model including cooling? • Semi-empirical model makes reasonable predictions • Replicates cooling after about 12 h • Assuming heating from beam power ( Nb, Ib^2, 1/Lb^2), cooling from radiation ( DT^4) and from conduction ( DT)

  7. Cooling coefficients • Use cooldowns at technical stops or MDs

  8. To do... • Fit all fills with same heating and cooling coefficients • Already started to extract cooling coefficients from the cooling curve when beam switched off • Update with October data • Extrapolate to 2012 and beyond • Derive some ‘operational’ limitations

  9. Concerns and possible upgrades • Reducing heating of MKIs • Reduced bunch length/better bunch shaping • New shielding with more stripes • Question – are temperature rises lower on kickers with more stripes? • Metalised chamber • Improving vacuum in MKIs • NEG coating of 2nd chamber? • Solenoids around 2nd chamber? • New SIS or SS interlocking/procedures? • UFOs in ceramic chambers with kicker pulsing • Coating? Cleaning? • Clearly need to group any upgrades and have common study with all aspects considered

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