update on STEP III

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# update on STEP III - PowerPoint PPT Presentation

update on STEP III. M. Apollonio University of Oxford. the case for STAGE III. first demonstration of cooling with solid absorber(s) ?. Chosen configuration must comply with coil/physics constraints : 1- max current 2- temp. margin 3- b (min)  minimise m.s. Matching Coils currents.

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### update on STEP III

M. Apollonio

University of Oxford

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the case for STAGE III

first demonstration of cooling with solid absorber(s) ?

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Chosen configuration must comply with coil/physics constraints:1- max current2- temp. margin3- b(min)  minimise m.s.

Matching Coils currents

Set up a procedure to find the right MC currents for a matched beam:a) b (trk1-2)=1/k, a=0b) fix b(min)

B (T) b(m)

Z (m)

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800 mm

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(b)

(a)

800 mm

(a)

(b)

T=98.4 %

T=97.9 %

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NB: beta_min = 49 cm (was 60cm at CM14)

means M1 1.4x, M2 0.7x

main issues

• current increase: is it within tolereances?
• magnet forces?
• MC distance = 800 mm. Can it be changed?

300 A!

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emittance growth in vacuum

DeT/eT=2.8%

eT (final)/eT (initial)

0 1 2 3 4 5 6

Z (m)

DeT/eT

2.8 %

Z (m)

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: emittance evolution in a cylindrical symmetric channel

non uniform Bz can cause

e growth (e.g. flip region)

ecalc9

MUC-NOTE 0071 prediction

Most of the effect explained

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Z (m)

emi vs Z

Pz vs Z

Beta= 70cm

-3%

-7.3%

Beta= 50 cm

-3%

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vacuum (no absorbers)

LiH absorber

LiH absorber - vacuum

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emi. % variation

vacuum growth subtracted

equilibrium

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Conclusion

• Slow B flip  emi growth. Has to be minimized
• a single absorber seems to work better
• the middle point cannot have a low beta  cooling effect reduced
• reduce beta_centre  increase M1 currents  forces
• better to place abs inside the II solenoid

 uneasy

6) transmission: large radius spool piece doesn’t seem to create dramatic effects

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