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Abstract

Magnets with good field uniformity in a good‐field region (GFR) of a certain volume are of interest for various research and calibration applications. Due to their simplicity and relatively low cost, Helmholtz coils have been the preferred

magnet system for such projects. With air cooling, the magnetic flux density possible with Helmholtz coils is limited to typically 1 mT or below, and field uniformity in the GFR is about one percent. A novel design based on Maxwell and

patented double‐helix (DH) or Constant‐Cosine‐Theta (CCT) winding configurations offer better field uniformity in the GFR (order of 1x10‐4) and enable much higher levels of flux density due to a much higher transfer function. The

novel systems can reach flux density levels of 10 mT with air cooling based on a cooling design in which all parts of the conductor are in direct contact with the airflow. The systems can be built with one, two or all three magnetic axes.

The coil configurations and complete designs of such systems with superior performance than Helmholtz coils are presented.

SpaceExploration,Multi‐AxesMaxwellCoilConfigurationSpaceExploration

AdvancedMagnetLab MT26

MEINKERainer,BAHADORIReza,ARAVINDAKSHANTa

Monte‐CarloParametricStudyonField

Uniformity

ConstantCosineTheta(CCT)CoilConfiguration

ContactInformation:

BAHADORI,RezaiswithiswiththeAMLSuperconductivityandMagnetics.(email:rbahadori2013@my.fit.edu).

MEINKE,RaineriswiththeAMLSuperconductivityandMagnetics. (e‐mail:rbmeinke@amlsm.com).

Aravindakshan,TAiswithFloridaInstituteofTechnology,UnitedStates(email:athirumalaia2015@my.fit.edu).

DesignVariables: Variable Range Length ofvariablerange

AWG ଵଵ

BigRadiusofEllipsoid ଶଶ

SmallRadiusofEllipsoid ଷଷ

NumberofTurnsRing1 ସସ

NumberofTurnsRing2 ହହ

NumberofTurnsRing3

XpositionofRing1

XpositionofRing2 ଼

XpositionofRing3 ଽଽ

NumberofLayersRing1 ଵ ଵ

NumberofLayersRing2 ଵଵ ଵଵ

NumberofLayersRing3 ଵଶ ଵଶ

Totalnumberofconfigurations:

ୀଵଶ

ୀଵ

Figure1.VariablesContributinginSpaceExplorationofAMaxwell

CoilSystem

The Maxwell equation suggest that best field uniformity appears in the center of a coil with ellipsoidal or spherical shape. An space

exploration a design study has been developed to calculate the field uniformity the center of a coil with spherical or cylindrical shape.

1stAxis‐‐‐ 6MaxwellRings

Specifications/DesignGoals

NumberofAxes DiameterofSphericalGFR FieldUniformity FieldStrength Lengthof Coil DiameterofCoil

3 50[mm] <1e‐4 10 [Gauss] <250[mm] <200[mm]

[mm]

[mm]

[mm]

[mm]

[mm]

[mm]

[mm]

[mm]

[mm]

Axis1 Axis2 Axis3

[mm]

[mm]

[mm]

[mm]

1st Axis

3rd Axis

2nd Axis

GFR

Specifications/DesignGoals

Number

ofAxes

Dimension of GFR Field

Uniformity

Field

Strength

Lengthof

Coil

Diameter

ofCoil

3 20x20x20[mm] <1e‐3 10 [Gauss] <250[mm] <90[mm]

•Constant‐Cosine‐Theta:

•Multi‐Axis,

•LargeAccessSize

SideView

Figure6.EffectofradiusofcylinderandlengthofcylinderinaCCTcoilconfigurationonthefielduniformitywith

20x20x20mmdimensionatthecenterofthecoil

Figure2.ThreeAxesMaxwellCoilSystem– DesignParametersforEachIndividualAxis

Figure3.ThreeAxesMaxwellCoilSystem– AssemblyConfigurationandMechanicalSupportDesign

Figure5.ThreeAxesCCT/SolenoidCoilSystem

Figure4.CCTCoilConfiguration

Emergingthe

CPU/GPUbased

parallelcomputing

machines.

Employing

probabilisticmethods

suchasMonte‐Carlo.

AMLhasdevelopeda

softwarecalled

“CoilCadTM”tomodel

varioustypesofcoil

systemsandperformall

calculationsrelatedto

Electromagnetsdesign

includingfielduniformity.

Monte‐CarloSpaceExploration

calculatefielduniformityinspecifiedGFRfora

randomlyuniformdistributionoutofallpossible

configurationsinareasonabletime

Obstacles:

•Large number of variables

contributing in the field

uniformity

•Difficult to find the best

possible combination of

variable by means of

experience.

•It is impractical to run all

possible configurations (Time‐

Consuming Simulation and

lack of memory)