1 / 15

FIELD QUALITY IN MQXA

CERN, 14 th February 2008 FiDeL meeting. FIELD QUALITY IN MQXA. E. Todesco Magnets, Cryostats and Superconductors Group Accelerator Technology Department, CERN. CONTENTS. Recall on MQXA Integrals DCloop Decay. Recall on MQXA. Interaction region quadrupoles made in Japan

ranae
Download Presentation

FIELD QUALITY IN MQXA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CERN, 14th February 2008 FiDeL meeting FIELD QUALITY IN MQXA E. Todesco Magnets, Cryostats and Superconductors Group Accelerator Technology Department, CERN

  2. CONTENTS • Recall on MQXA • Integrals • DCloop • Decay

  3. Recall on MQXA • Interaction region quadrupoles made in Japan • Q1 and Q3 parameters • Magnetic length: 6.3 m • Operational gradient 215 T/m • Operational current: 7150 A • Injection current: 435 A • Number: 16+2 spares • ID: MQXA2-MQXA19 • Design • Four layers, two cables, special grading • Iron close to the coil, large saturation • A systematic b4 created by the yoke assembly procedure

  4. Recall on MQXA • Magnetic measurements at 1.9 K • Integrals • Measurements at 1.9 K, loadline, ramp up • At 6 currents, from inj. to coll. • 3 positions: central and two heads, covering all the magnet • DCloop • Measurements at 1.9 K, loadline ramp up and down 2 times • At 20 values of current for each ramp • 5 positions: 3 central and 2 heads with 600 mm rotating coils (gaps left) • Missing heads for half of the magnets • Decay • Measurements at 1.9 K, at injection and at collision • Measurements each 3 minutes for 200-300 minutes • 1 central position with 600 mm rotating coils

  5. INTEGRALS • Magnetic measurements at 1.9 K • Loadline, 6 values of the current from injection to high field • A body measurements, plus two heads • Cover all the magnet • 5400 mm length in the body • Transfer function values set to the central value also for the heads, but magnetic length is given • These are the reference values for the geometric

  6. DCLOOP • DCloop • Measurements at 1.9 K, loadline ramp up and down 2 times • At 20 values of current for each ramp • 5 positions: 3 central and 2 heads with 600 mm rotating coils (gaps left) • Missing heads for half of the magnets • Current cycle • A loadline: down-up-down-up • 20 currents per ramp from 50 A to 7344 A • Note: injection 435 A, collision 7150 A • A ramp up (or down) takes 2.5 h • Measuring positions • 5 positions, 600 mm coil, 2 in heads • Gaps!

  7. DCLOOP • Post-processing • Original measurements available in FiDeL format • Integrals computed assuming that caps behave as straight parts • In case of missing heads (MQXA2-8), the missing measurement is replace by an average of the measurements in the heads (MQXA-9-18) • Agreement with the INTEGRAL measurements is within 1-7 units for the transfer function • Good agreement with INTEGRAL measurements for multipoles (less than 0.1 units on averages over 18 magnets, in general within 0.1 units for each magnet, with a few exception up to 0.5 units) • First and second ramp difference • Transfer function reproducible within a few units • Multipoles: the same within 0.1 units or less • Systematic decrease of b6 of around 0.1 units after the first ramp (?)

  8. DCLOOP • Transfer function • Width of the hysteresis at injection: 33 to 38 units • Saturation at high field: 5.2-5.3 % (520 to 530 units) – large !! (and different from the MQXB) MQXA2 transfer function

  9. DCLOOP • Transfer function • Spread at injection: 3.5 units (1 s) • Spread at high field: 3.0 units (1 s) • These are extremely low values compared to other quadrupoles! • Confirmed by the independent measurement INTEGRAL MQXA transfer function at injection MQXA transfer function at high field

  10. DCLOOP • b6 • Width of hysteresis at injection: 2.8-2.9 units b6 in MQXA2

  11. DCLOOP • b6 • Spread at injection: 0.8 units (1 s) • Spread at high field: 0.6 units (1 s) • Reasonable values, large variation at high field compared to injection • Average at injection: -1.0 units • Average at high field: 0.34 units • Very good optimization MQXA b6 at injection MQXA b6 at high field

  12. DECAY • Decay • Measurements at 1.9 K, after a cycle at ? • Measurements for 200-300 minutes, each 3 minutes • 1 central position with 600 mm rotating coils • Measurements at injection and at high field • At high field – most critical • No expected decay • Measurements show b1 stable within 0.5 units, and low order multipoles stable within 0.1 units

  13. DECAY • Decay of b6 at injection • After 20 minutes, from 0.25 to 0.8 units • After 300 minutes, from 0.5 to 1.3 units

  14. DECAY • Decay of b4 at injection • After 20 minutes, from -0.25 to 0.1 units • After 300 minutes, from -0.4 to 0.4 units

  15. DECAY • Decay of transfer function at injection • After 20 minutes, from -4 to 1 unit • After 300 minutes, from -8 to 3 units

More Related