# Standard Helmholtz Coils

Helmholtz Coils are ideal for the measurement of Rare Earth (Samarium Cobalt, Neodymium) and Hard Ferrite permanent magnet materials (materials which exhibit a relative straight line demagnetization). Our standard Helmholtz Coils are for use with fluxmeters. The Helmholtz Coil measures the magnet sample as a single magnetic moment provided that the longest dimension of the magnet sample is less than one-third (1/3) the diameter of the coil system. By definition, the magnetic moment per unit volume is the intrinsic magnetization of the sample. With our calibrated Helmholtz Coil and Integrated Fluxmeter – and given the volume of the permanent magnet sample – the intrinsic open circuit operating B (Bdi) can be measured.

The Helmholtz Coil and Fluxmeter are used for the measurement of a wide range of magnet sizes, materials, and geometries without specimen destruction, complicated set-up times, or bulky and expensive equipment. Complex geometries common with Neodymium, Samarium and Hard Ferrite permanent magnets, including motor arc segments, can be easily measured. Consult one of our experienced engineers for design and application assistance.

## FEATURES

• Simple, Easy to Use, Fast
• Highly Reliable, Repeatable
• Wide Range of Sizes Available
• Performs a Non-destructive Test
• Economical
• Production and Research Measurements
• Accurate Inspection of Magnetized Magnets
• Measurement of Calibrated Magnets Assurance of Magnet Saturation

Place the sample to be measured in the center of a correctly sized Helmholtz Coil. Reset the fluxmeter. Upon removal of the magnet sample, the time integral of the induced voltage, which is equal to the total flux of the dipole magnet, approximates the field uniformity for the relationship of fluxmeter reading to the following:

The following relationship exists:
$Bd_i&space;=&space;frac{Reading&space;cdot&space;Range&space;cdot&space;Coil&space;&space;Constant}{Magnet&space;&space;volume&space;&space;in&space;&space;Cubic&space;&space;Centimeters}$

## Physical Specifications

 Model No. Longest Magnet Dimension Dim. A Dim. B Dim. C in. mm in. mm in. mm in. mm HC- 1.5 0.5 13 1.5 38 2.75 70 2.15 55 HC-3 1.0 25 3.0 76 5.0 127 2.88 73 HC-5 1.6 41 5.0 127 6.95 176 3.86 98 HC-8 2.6 66 8.0 203 9.80 249 5.33 135 HC-12 4.0 >102 12.0 304 13.95 354 7.60 194

NOTE: Custom designs are available upon customer’s request.