basic parameters

EMMA Hardware Meeting 1/7/06Neil Marks

EMMA BASIC PARAMETERS

‘BF’ magnet

‘BD’ magnet

Bend angle -0.04994 0.1995 rad

Dipole strength 1.67 E-03 6.65 E-03 Tm

B Length 0.55 0.65 m

Dipole flux density 0.0302 0.102 T

Max quad gradient 9.3 5.8 T/m

Extent of good gradient 39 + 59, - 0 mm

At ‘reference’ orbit (10 MeV?)


EMMA COMBINING DIPOLE & QUAD FIELD

• from experience, combining variable dipole and quadrupole field in the same magnet is difficult and expensive;

• the series of ‘allowed’ harmonics in dipoles is n = 1, 3, 5, etc; ie dipoles are quadrupoles are ‘chalk and cheese’;

• the parameters given above show that the EMMA magnets are substantially quadrupole magnets with low dipole components;

SOLUTION:

• build the EMMA magnets as pure quadrupoles;

• position them off-centre to provide the dipole component;

• when the ratio dipole/quadrupole needs to be varied, adjust the quad field and move the magnets radially to retain to correct dipole field.


EMMA MOVING MAGNETS DURING OPERATION

• In HERA (DESY), e- spin transfer into the longitudinal plane requires a horizontal and vertical bump to be applied after vertical polarisation has been achieved –

• horizontal is applied first;

• then the vertical bump is applied and magnet positions changed to keep beam inside the vacuum vessel.

IS NOT NEW!

With thanks to Prof. Des Barber, DESY and U. of Liverpool. – see http://www.lancs.ac.uk/cockcroft-institute/education/Barber_spin_June06.ppt


EMMA BEFORE AND AFTER

Before vertical bump is applied.

After vertical bump is applied.

With thanks to Prof. Des Barber, DESY and U. of Liverpool. – see http://www.lancs.ac.uk/cockcroft-institute/education/Barber_spin_June06.ppt


EMMA RESULTING MAGNET PARAMETERS

‘BF’ magnet

‘BD’ magnet

Inscribed radius 44 56 mm

Peak gradient 9.3 5.8 T/m

Good gradient region 39 + 59, - 0 mm

Good gradient quality 0.2% 0.2% g(x)/g(0)

Type of magnet full quad. half quad, mirror plate

Required radial movement

7 12 mm

Amp-turns/pole ( = ) 7164 7237 At

Turns/pole (I = 200 A) 36 36

Magnet thickness 55 65 mm

Limit on coil overhang 19 19 mm

Coil construction 2 layers of 18

turns, 8mm x 8mm.

Design current density 3.0 3.0 A/mm2


EMMA ‘BF’ MAGNET FEA GEOMETRY

One eighth cross section used for 2D f.e.a of BF magnet.


EMMA ‘BF’ GRADIENT QUALITY (LINEAR STEEL)

Expressed as: (dBy/dx (x,0))/By/dx (0,0);Gradient: 10.1 T./m at J = 3.2 A/mm2;Gradient quality: + 0.25% at x = 34 mm; -0.35% at x = 39 mm;Max induction in pole root: 1.24 T.


EMMA ‘BF’ GRADIENT QUALITY (NON-LINEAR STEEL)

Identical quality to linear steel case.

Gradient: 9.96 T;Hence, amplitude linearity: 98.6 %.


EMMA RESULTING ‘BF’DESIGN


EMMA ‘BD’ MAGNET FEA GEOMETRY

One eighth cross section used for 2D f.e.a of BD magnet; half-magnet geometry and mirror plate ignored (for the moment).


EMMA ‘BD’ GRADIENT QUALITY (LINEAR STEEL)

Expressed as: (dBy/dx (x,0))/By/dx (0,0);Gradient: 6.19 T/m at J = 3.2 A/mm2;Gradient quality: + 0.04% at x = 45 mm; -0.28% at x = 59 mm;Max induction in pole root: < 1.0 T.


EMMA HALF ‘BD’ MAGNET WITH MIRROR PLATE


EMMA HALF ‘BD’ GRADIENT QUALITY (LINEAR STEEL) on y = 0 axis

Expressed as: (By/dx (x,0))/By/dx (0,0); between x = 5 and x = 60;(steel at x = 0 gives singularity in dBy/dx);Gradient quality: + 0.1% at x = 55 mm; - 0.25% at x = 59 mm.


EMMA HALF ‘BD’ GRADIENT QUALITY (LINEAR STEEL) on x = 0 axis

Expressed as: D(Bx/dy (0,y))/Bx/dy (0,0); between y = 0 and y = 30;Gradient quality: + 0.03% at y = 30 mm;


EMMA RESULTING ‘BD’ DESIGN


EMMA CELL LAYOUT GEOMETRY

NOTE MAGNET PROXIMITY


EMMAINJECTION/EXTRACTION

PATH

Note injection line cutting through mirror plate on median plane

basic parameters

Documents