• Combined function Magnets for Diamond ddba. • Chris Bailey

Low emittance rings

Jul 8-10 2013 Oxford

Lattice and Magnets

3.4m mid-cell straight

55 T/m

30 cm

55 T/m

25cm -14 T/m

66cm

-15 T/m

96cm

55 T/m

15cm50 T/m2 20cm

V5

Half ddba cell shown:-Gradient Dipoles, mechanical tolerances.Quadrupoles reasonably strong but not too challenging.Sextupoles, strong and small bore, still need to include the majority of correctors.Extra correctors (not shown), space very limited, looking at over bellows location.

Combined function dipoles• 2 lengths with different gradients• 0.8 T with -14 Tm-1 66cm and -15 Tm-1 96cm• Longitudinal space, coils mounted on back leg and flush with

pole length.Effective length of magnet with current roll off is ~102% of steel length

• Must be possible to change in situ.• Magnet will need to split in two, coils would not be possible to fit

through gap even if mounted on pole.• Pole stability needs to be good there may need to be non-

magnetic bracing.• Currently modelled with ~90% of the Aturns coming from the

existing main dipole circuit with additional trim coils.

Model to assess effects of end profiles and back leg coils

3D effects

-8 -6 -4 -2 0 2 4 6 8800

805

810

815

820

825 Leff

Leff -6 -4 -2 0 2 4 60.01450

0.01470

0.01490

0.01510

0.01530

0.01550

db/dx(spot)db/dx(Int_800)dBy/dx(100)dBy/dx(300)

Current end profile results in systematic variation in effective length.

There is variation in the gradient along the magnet length, and when compared spot values to integrated effects

Effect of mechanical errors of fields (2D calculations)

-25 -20 -15 -10 -5 0 5 10 15 20 25

-6.0000

-4.0000

-2.0000

0.0000

2.0000

4.0000

6.0000

Field Errors mT

nominal"50 resolution"-50 micron"+50 micron""-twist""+twist""+50 convex""50 concave"100 bump -5 to zero

Position mm

Same calculations shown as gradient %deviation from -15Tm-1

-20 -15 -10 -5 0 5 10 15 20

-1.0000

-0.5000

0.0000

0.5000

1.0000

1.5000

Gradient Errors

nominal100 bump -5 to zero-50 micron"-twist""+twist""50 resolution""+50 micron""+50 convex""50 concave"

Position mm

% e

rror

Sextupole with correctors• 4000 Tm-2

• 3 lengths 0.2,0.25,0.3 m• H & V steering + Skew Quad

function.• Quality Δg/g ~10-2

• Steerers using same design power supply as existing ones, coils not yet fitted into design.

• Checking with 3D modelling that the corrector and sextupole fields are decoupled

Courtesy S Mhaskar

2 axis corrector• Physical length 100 mm.• Probably positioned over bellows:- aperture 140 mm.• All end field: how will this interact with surroundings.• What is the required field quality?• What is really the required strength• Design very similar to one already in use in 2 locations in

Diamond.

Alternative design...The field quality is better, but the strength is insufficient and it does not seem to be possible to increase significantly. The magnet grows too fast.

Modified windowframe (above)

Crossed poles (previous slide)

S Mhaskar, N Marks

Summary• Dipoles :- Only -15Tm-1 modelled. • 3D models with Curvature and end profiles not yet combined.• No Modelling yet of means to correct harmonics resulting from

tolerance in build.• 50 micron defects correlate to a change of 0.5% in gradient.

• Quadrupoles look complete.

• 2 axis corrector: Can the field be improved.

• Sextupoles, needs to be remodelled slightly larger to integrate corrector windings.