EM-4V and EM-7V Electromagnets
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EM-4V and EM-7V Electromagnets

Lake Shore

The Lake Shore EM-4V and EM-7V electromagnets (EM-V Series) produce magnetic fields with a variety of indexed air gap and pole cap configurations. The EM-V Series are ideally suited for integration into customer-designed magnetic test platforms for applications including magneto-optical studies, magnetic hysteresis studies, in-line annealing, Hall effect studies, susceptibility measurements, spin magnetic resonance demonstrations, and biological studies.

The EM-V series magnet coupled with a Lake Shore magnet power supply (MPS) and teslameter form a versatile laboratory electromagnet capable of producing magnetic fields up to 3.26 T and supporting very fast ramp rates of up to 1 T/s. This system, with true bipolar MPS power output, provides rapid uniform magnetic field ramping and field reversal to avoid discontinuities that occur during zero crossover when using unipolar power supplies.

ExactGAP™ indexed gap settings

The EM-V Series electromagnets feature ExactGAP™ indexed pole settings. The ExactGAP pole gap indexing makes it fast and easy to reconfigure the magnet gap for the required sample or option size without having to re-calibrate the magnet after changing the gap. Choose from 6 repeatable gap widths by unbolting the top plate and clicking the selector into place. The EM-V Series incorporate water-cooled coils and precision yokes made of magnetically soft, ultra-pure steel, assuring precise pole cap alignment as well as excellent field homogeneity and stability.

  • Indexed pole gap settings (ExactGAP™) allow repeatable air gap changes without having to re-calibrate between changes
  • Exceptional field intensities achieved with cylindrical or tapered pole caps
  • Water-cooled coils provide excellent field stability and uniformity
  • Removable pole caps facilitate variable pole face configurations and easy pole cap exchange
  • Accurate pole alignment by precise construction of the air gap adjustment mechanism
  • The EM-4V/EM-7V yoke designed for optimum air gap accessibility for both top and bottom of the magnet
  • Compact size of the EM-4V permits convenient bench-top mounting
  • Optional optical access pole caps available

EM-V Series Specifications

EM-4V typical field uniformity

 Magnet configuration

Uniformity over 1 cm2

1% cylindrical volume

 Pole cap
mm (in)

Air gap
mm (in)

Diameter
mm (in)

Length
mm (in)

102 (4.0)

51 (2.0)

±0.15%

18 (0.7)

51 (2.0)

102 (4.0)

25 (1.0)

±0.05%

64 (2.5)

25 (1.0)

76 (3.0)

25 (1.0)

±0.06%

46 (1.8)

25 (1.0)

51 (2.0)

25 (1.0)

±0.35%

18 (0.7)

25 (1.0)

51 (2.0)

13 (0.5)

±0.16%

36 (1.4)

13 (0.5)



EM-7V typical field uniformity

 Magnet configuration

Uniformity over 1 cm2

1% cylindrical volume

 Pole cap
mm (in)

Air gap
mm (in)

Diameter
mm (in)

Length
mm (in)

51 (2.0)

16 (0.6)

±0.11%

28 (1.1)

16 (0.6)

51 (2.0)

25 (1.0)

±0.33%

10 (0.4)

25 (1.0)

102 (4.0)

16 (0.6)

±0.03%

74 (2.9)

16 (0.6)

102 (4.0)

25 (1.0)

±0.03%

66 (2.6)

25 (1.0)

102 (4.0)

38 (1.5)

±0.05%

48 (1.9)

38 (1.5)

102 (4.0)

51 (2.0)

±0.08%

23 (0.9)

51 (2.0)

NOTE: The third column gives uniformity over one cubic centimeter volume centered in the magnet gap. The last two columns give the cylindrical volume within which the magnetic field deviates by less than 1% from the central field. The cylindrical volume is coaxial with the magnet poles and centered in the gap.



General specifications

 

EM-4V

EM-7V

Air gaps

With no pole caps

57.5, 62, 70, 75, 78, and 100 mm

 

With 2 in pole caps

7.5, 12, 20, 25, 28, and 50 mm

Coil resistance, nominal

0.25 Ω per coil
(0.5 Ω total wired in series)

1.00 Ω per coil
(0.5 Ω total wired in parallel)

Coil resistance, cold

0.23 Ω per coil
(0.46 Ω total wired in series)

0.92 Ω per coil
(0.46 Ω total wired in parallel)

Coil resistance, maximum

0.27 Ω per coil
(0.54 Ω total wired in series)

1.08 Ω per coil
(0.54 Ω total wired in parallel)

Integrated pole diameter

100 mm (4 in)

178 mm (7 in)

Available pole cap diameters

50 mm (2 in)

100 mm (4 in) and 50 mm (2 in)

Cooling water

Tap water or closed cooling system

Water flow rate

7.6 L/min (2 gal/min)

11.4 L/min (3 gal/min)

Pressure drop

200 kPa (30 psi)

220 kPa (32 psi)

Water chiller cooling capacity

2.5 kW (8,530 BTU/h)

5.0 kW (17,060 BTU/h)

Water inlet temperature

15 °C to 25 °C (59 °F to 77 °F)

Coil over temperature limit

45 °C (113 °F)

Coil spacing, nominal

121 mm (4.75 in)

178 mm (7 in)

Coil size-width, nominal

121 mm (4.75 in)

132 mm (5.2 in)

Coil size-diameter, nominal

311 mm (12.25 in)

445 mm (17.5 in)

Current (maximum continuous operating)

±70 A

±135 A

Voltage, nominal

±35 V (approximately 38 V at maximum coil temperature)

±70 V (approximately 38 V at maximum coil temperature)

Continuous input power, nominal

2.5 kVA (2.65 kVA at max temperature)

9.45 kVA (10.125 kVA at max temperature)

Suggested power supply

Lake Shore Model 643

Lake Shore Model 648

 

Size

Height

77 cm (30.3 in)

52.7 cm (20.8 in)

Width

78.7 cm (31 in)

78.7 cm (31 in)

Depth

88.9 cm (35 in)

88.9 cm (35 in)

Weight of yoke and coils, no rolling base or pedestal, approximate

227 kg (500 lb)

567 kg (1250 lb)

Weight

201.9 kg (445 lb)

635 kg (1400 lb)

Shipping weight

215.5 kg (475 lb)

660 kg (1500 lb)

Shipping dimensions

0.97 m × 0.58 m × 0.56 m
(38 in × 23 in × 22 in)

0.86 m × 1.22 m × 1.19 m
(34 in × 48 in × 47 in)