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Update on MQM and MQY models (work in progress)

Update on MQM and MQY models (work in progress). W. Venturini Delsolaro Fidel meeting 26/5/2009. Outline. Scaling for operational temperature (MQM) Update on minimum pre cycle currents Fit of penetration curve, new Fidel component.

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Update on MQM and MQY models (work in progress)

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  1. Update on MQM and MQY models (work in progress) W. Venturini Delsolaro Fidel meeting 26/5/2009

  2. Outline • Scaling for operational temperature (MQM) • Update on minimum pre cycle currents • Fit of penetration curve, new Fidel component

  3. Effect of MQM operational temperatures (1.9K – 4.2 K) on the TF

  4. MQM35 measurements results (1.9K – 4.2 K) v 2008 model as it was (p=0.6, q=0.95)

  5. Isolating the “magnetization component” data and refitting the pinning exponents… (p=1, q=1.5)

  6. Summary on temperature effect • MQM35 measured in 2006 at the two temperatures • The Jc(T) scaling in the present model works very well • But for that we must not use the pinning exponents to fit others features of the data! • Need to re fit the RESIDUAL MAGNETIZATION. Done • Despite apparently possible (contrary to MQY) it is not a good idea to use RES MAG to fit penetration curves! • In summary a new iteration on all the components was done, before going back to the penetration curve….

  7. ..fitting the penetration curves, and putting all together • New component (penetration): • Tried with A=-µ/2, did not work • A = -11.5 µ/2 works. Fitting points at 100A 200A and 265A • New range for MQM: 100 A  5390 A  350A. So far 8 apertures done with similar results (errors in units) using the same parameters.

  8. Update on minimum currents • For MQY the minimum injection current is ~133A, while for MQM it is ~145 A • Minimum MQY current during squeeze ~ 800 A (Q5.L2) • Minimum MQM current during squeeze ~ 388 A (Q6.L5) • According to D. Nisbet, it should be possible to set the minimum operating current to 100A for the all IPQ circuits. Nominal ripple performance will be granted above 120A. • Special measurements on MQM become less urgent • Need to decide on the minimum before the start of HWC • Incorporate in the powering procedures, best an ECR

  9. MQY fits, update • Model 2008: max |ε| ~ 5 units between 176 A and 3600A • New model with q=19 and penetration : gave promising results on 13 apertures down to 130 A. (Imin =100 A) • Now trying same penetration function as for MQM, third iteration. Ongoing

  10. Summary • The temperature scaling in the model fits the experiment well. From Fidel side, nothing to change • Need to verify that in LSA the scaling is applied, taking into account the operational temperatures • The best solution for the low injection currents issue seems to be: adding a component to the model thus extending its validity to cover the re-penetration curves. Work is still progressing to cover all available data. • REFPARM files and LSA to be adapted (very soon) • A small ECR needs to be issued to set I min op to 100A, to profit from the series measurement data • To be reflected as well in the pre cycling prescriptions...

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