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Product Catalog:

Magnetic Field Coil

• Helmholtz Coil
• DXMC-1MF Helmholtz Coil
• Solenoid

Product Detail:

Helmholtz Coil

Introduction of Helmholtz Coil:

Hermann von Helmholtz (1821-1894) German scientist and philosopher who made fundamental contributions to physiology, optics, electrodynamics, mathematics, and meterology. Helmholtz Coils A pair of conducting circular coils each having N turns, each carrying a current I, separated by a distance equivalent to the radius of the circular loops, produce a homogeneous magnetic field B in the mid-plane between the two circular coils. a = radius of the coils a = separation between the coils a/2 = distance to the mid-plane B = magnetic field at the mid-plane

What creates a magnetic field? A magnetic field is created whenever charge is in motion--either moving in space or spinning around itself. A charge moving in space is called a "current" (denoted by the symbol I) and is measured in coulombs/sec or amperes. The strength of magnetic field is measured at a point in space (often called the field point). In the case of the Helmholtz coils, the field points of interest are located in the mid-plane between the two coils. As shown in the equation above, the strength of the magnetic field is dependent upon three quantities: the current I, the number of turns N in each coil, and the radius a of the coil. The total current in each coil is NI.

 

How uniform is the magnetic field? The "claim to fame" for the Helmholtz coil is its very uniform magnetic field. However, the question that naturally arises , "how uniform, and over what distance?" To determine the uniformity of the magnetic field requires more than the above equation and involves some complicated integral calculus. However, we can generate some figures that graphically show how the magnetic field varies on the mid-plane as a function of r (the distance from the axis of symmetry passing between the centers of the two coils) and d the separation between the two coils.		Coil spacing is "too close." d = 0.8 a
In the figures to the right, we can see how uniform the magnetic field is on the mid-plane when the spacing d is too close, just right, and too far. The figures to the right are calculated for coils with a radius of 20 cm (i.e., a = 0.20 m). The following integral was evaluated to produce the three curves at the right.		Coil spacing is "just right." d = a
where the factor of "2" in the numerator takes into account the two coils, and b = d/2 is the distance from each coil to the mid-plane.		Coil spacing is "too far." d = 1.2 a

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How does the region of uniform magnetic filed vary with the radius of the Helmholtz coils?

The figures below show the range of uniform magnetic field as a function of the coil radius.

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Here is a lab writeup describing the procedure for measuring the charge-to-mass ratio of an electron using the Helmholtz coils.

 

Using two same coils with equal radius and turns,arrange them to be coaxial and let their distance be equal to the radius of the coil,this called Helmholtz coil. It can be used to generate magnetic field from extremely weak magnetic to hundreds of Gauss.

Specifications:

Model	Shape	Averageradius (cm)	Center magnetic field (Gs)	Power (W)	Weight (Kg) (one axis)
DXHC150-2	Square	150	2	540~620	84
DXHC 100-10	Square	100	10	1200~1500	180
DXHC 100-5	Square	100	5	600~800	94
DXHC 100-2	Square	100	2	220~300	58
DXHC 75-10	Square	75	10	700~900	80
DXHC75-5	Square	75	5	360~430	53
DXHC75-2	Square	75	2	150~180	21
DXHC60-10	Square	60	10	500~600	68
DXHC60-2	Square	60	2	100~120	14
DXHC50-20	Square	50	20	600~700	61
DXHC50-10	Square	50	10	350~430	47
DXHC50-2	Square	50	2	70~90	15
DXHC40-50	Square	40	50	1000	98
DXHC40-10	Square	40	10	220~300	30
DXHC40-2	Square	40	2	45~60	15
DXMC30-100	Round	30	100	800	80
DXMC30-50	Round	30	50	500	40
DXMC30-10	Round	30	10	100~200	17
DXMC30-2	Round	30	2	24~48	8
DXMC25-1000	Round	25	1000	5000	500
DXMC25-500	Round	25	500	3000	250
DXMC25-300	Round	25	300	1800	150
DXMC25-200	Round	25	200	1200	100
DXMC25-100	Round	25	100	600	50
DXMC25-50	Round	25	50	300	25
DXMC25-10	Round	25	10	60~90	12
DXMC25-2	Round	25	2	12~18	8
DXMC20-500	Round	20	500	2000	160
DXMC20-300	Round	20	300	1200	96
DXMC20-200	Round	20	200	700	64
DXMC20-100	Round	20	100	350	32
DXMC20-50	Round	20	50	200	16
DXMC20-10	Round	20	10	40~65	8
DXMC20-5	Round	20	5	20~32	6
DXMC20-2	Round	20	2	8~15	5
DXMC15-300	Round	15	300	660	54
DXMC15-200	Round	15	200	430	36
DXMC15-100	Round	15	100	220	18
DXMC15-50	Round	15	50	110	9
DXMC15-10	Round	15	10	21~42	6
DXMC10-200	Round	10	200	200	20
DXMC10-100	Round	10	100	100	15
DXMC10-50	Round	10	50	50	8
DXMC10-10	Round	10	10	10~24	6
DXMC7-100	Round	7	100	50	7
DXMC7-50	Round	7	50	24	4
DXMC7-10	Round	7	5-12	10	2

Note: the models in red color can be made into three axis coils.

 

Feature: 

Open space, easy to use, magnetic field has a good linear relationship with current, magnetic field space has a very wide uniform area,which is suitable to generate one-dimensional, two-dimensional and three-dimensional space composite magnetic field.

Application:

 1.to generate standard magnetic field
 2.calibration for Hall probes and various magnetometers
 3.compensation for earth magnetic field
 4.judgement for magnetic shielding effect
5. measurement and removement for space radiation magnetic field
 6. for magnetic properties
 7.study for biomagnetism

Note:

 Magnetic field intensity: the value of the magnetic field in the magnetic field center,when power is maximum
Uniform area: the relatively homogeneous magnetic field space surrounding magnetic field centre, or the required magnetic field for users’experiments
Space uniformity: the magnetic deviation degree in uniform area
Stability: the degree of change when the magnetic field working over a period of time.
Working time:the longest using time
Work period: the interval time between continuous work for more than two times

Our company specializes in the design and production of the Helmholtz coil, could put forward design scheme and proceed multi-dimensional space design according to the magnetic field strength, magnetic field homogeneity and uniformity level. With precise design, precise calculation and elaborate manufacture, our products have been chosen for the tertiary institutions, research units and the vast majority of users,received high reputation.