MMR Technologies
Hall Measurement Systems
MMR's Variable Temperature Hall System (VTHS) allows the user to make automatic measurements of resistivity, mobility and carrier concentration of a wide range of samples using the Van der Pauw method over a temperature range from 70K to 730K. Sample mounting is simple and allows rapid interchange of samples. The VTHS Hall Measurement Controller, the H-50, is compatible with a variety of computers through an IEEE-488 (GPIA) or RS-232 interface. MMR's Benchtop Electromagnet and Programmable Power Supply complement the VTHS. The system uses the VTHS Dewar described below.
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Operating Temperature: 70 K to 730 K
- Guarded Triax Leads
- H-50 interfaces with MMR's Low Temperature Dewar
- H-50 interfaces with MMR's K-20 Programmable Temperature Controller
- H-50 interfaces with two different MMR electromagnets, allowing maximum flexibility in sample analysis.
- Hall magnetometer in Dewar included in system
- Full software provided for all measurements
- Power Input: 110 V, 60 Hz and 220 V, 50 Hz
- H-50 Weight: 12 lb
- H-50 Dimensions: 3.5" x 17" x 14"
Variable Temperature Hall Dewar
The VTHS Dewar is a low-profile Dewar designed to fit between the poles of a magnet to enable measurements to be made of the resistivity, Hall mobility and other properties of materials over a wide range of temperatures. Guarded triax leads provide electrical input to the sample via similarly guarded leads on a Kapton Harness to the sample on the cold stage. A Hall sensor immediately adjacent to the sample allows measurement of the magnetic field at the sample location.
In addition to the refrigerator and vacuum chamber, a temperature controller is needed, either manual or programmable; a source of dry nitrogen (99.998% purity); a filter dryer; and a vacuum pump capable of maintaining a vacuum <5 mTorr in the chamber. Other accessories that add to the convenience of operating the system are available from MMR.
- Operating Temperature: 70 K to 730 K
- Temperature Stability: ± 0.1 K with K-20 Programmable Controller
- Temperature Response: 1 K/sec
- Cooling Capacity: 250 mW at 85 K with nitrogen; 500 mW with Ar at 90 K
- Cold Pad Size: 14 mm x 10 mm
- Standard Window Material: Fused silica
- Optional Window Materials: Sapphire, KRS-5, Ge, etc.
- Guarded triax leads to sample
- Four sample leads for Van der Pauw measurements
- Extra BNC lead for heater for Seebeck measurements
- Simple sample mounting
- Integral Hall sensor at sample site
- Compatible with two different MMR electromagnets, allowing maximum flexibility in sample analysis
- Dewar Dimensions: 6.0" L x 2.5" W x 0.75" H at sample
- Weight of Vacuum Chamber: 170 g (6 oz)
M-25 5000 Gauss Permanent Magnet
MMR's Model M-25 Benchtop Permanent Magnet has been designed for use with MMR's Variable Temperature Hall System; the VTHS refrigerator and Dewar mount between the poles of the magnet. The magnet may also be used for a variety of other laboratory applications. It requires neither water- nor fan-cooling. It is a compact, efficient magnet standing only 7.5" high, and it occupies only 4" x 3" of bench space. It provides a vertical field of 5000 gauss between flat 2.5" x 3.0" pole pieces with a 0.75" gap. The size of the gap has been designed specifically for a good fit with the Hall Dewar System.
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Pole Piece Dimensions: 2.5" x 3.0"
- Pole Gap: 0.75”
- Weight: 55 Kg (25 lb)
MK-50 5000 Gauss Electromagnet with MPSK-50 Power Supply
MMR's Model MK-50 Benchtop Electromagnet has been designed for use with MMR's Variable Temperature Hall System; the VTHS refrigerator and Dewar mount between the poles of the magnet. The magnet may also be used for a variety of other laboratory applications. It requires neither water- nor fan-cooling. It is a compact, efficient magnet standing only 7.5" high, and it occupies only 10" x 16" of bench space. It provides a vertical field of 5000 gauss with a 0.75" gap at 8 amps. The size of the gap can be easily adjusted.
The magnet is designed to be used with MMR's MPSK-50 Programmable Power Supply, and the VTHS-D Hall System Dewar, to provide rapid and simple determination of Hall mobilities of semiconductors over a wide range of sample temperatures from 70 K to 730 K.
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Compatible with MMR MPSK-50 Magnet Power Supply
- Reversal Time (+5000 to -5000 gauss): 2 seconds
- Pole Gap: 0.75”
- Operating Temperature: 0°C to 50°C
- Chiller or Water cooling available through easy access back ports to extend operation time and minimize heat impact on experiment
- Weight: 36.5 Kg (80 lb)
M-150 14000 Gauss Electromagnet with MPS-150 Power Supply
MMR's Model M-150 Large Field Electromagnet is supplied with a 38 mm face diameter pole pair to provide the highest field versus current values. It provides a vertical field of 14000 gauss, operating with up to 40 amps of current. Higher current is possible but requires magnetic power supplies other than those provided by MMR Technologies. The size of the gap can be easily adjusted.
The magnet is designed to be used with MMR's MPS-150 Programmable Power Supplies, the C150 Chiller system, and the VTHS-D Hall System Dewar, to provide rapid and simple determination of Hall mobilities of semiconductors over a wide range of sample temperatures from 70 K to 730 K
- Compatible with MMR MPS-150 Magnet Power Supply
- Maximum Current: ± 40 amps at 20 Volts
- Reversal Time (+14000 to -14000 gauss): 2 seconds
- Pole Gap: 0.75”
- Operating Temperature: 0°C to 50°C
- Weight: 125 kg (275 lb)
- Chiller or Water cooling available through easy-access back ports to extend operation time and minimize heat impact on experiment
Power Supplies
MMR's Model MPSK-50 Programmable Power Supply is a 240 Watt, fully reversible power supply providing up to ±8 amps at up to ±30 volts. It is continuously controllable over both the current and voltage range window. The front panel liquid crystal display shows the voltage and current and any operating or error messages.
Easy to use, the only front panel controls are the reset button and display viewing angle adjustment. All controls are handled by a personal computer via an IEEE-488 (GPIB) or RS-232C interface, both interfaces are included in the MPSK-50.
MPSK-50 Power Supply
- Compatible with MMR MK-50 Benchtop Electromagnet
- Field Operating Range: +5000 to -5000 gauss
- Maximum Current: ± 10 amps
- Current range: -10 to +10 amps
- Voltage range: -20 to +20 volts
- Output Power: 0 to 400 Watts
- Transient Response Time: 30 µs
- LCD Front Panel Display
- Operating Temperature: 0° C to 55° C
- Input Voltage: 120 ±5 VAC or 240 ±10 VAC
- Load Regulation, Voltage: 0.0000004 mV
- Load Regulation, Current: 1mA
- Dimensions: 19" L x 21" W x 6" H
MPS-150 Power Supply
- Compatible with MMR M-150 Electromagnet
- Work as a master/slave pairv
- Field Operating Range: +14000 to -14000 gauss
- Maximum Current: ± 20 amps (40 amps as a working pair)
- Current range: -20 to +20 amps (40 amps as a working pair)
- Voltage range: -20 to +20 volts
- Output Power: 0 to 400 Watts (800 Watts as a working pair)
- Transient Response Time: 30 µs
- LCD Front Panel Display
- Operating Temperature: 0° C to 55° C
- Input Voltage: 120 ±5 VAC or 240 ±10 VAC
- Load Regulation, Voltage: 0.0000004 mV
- Load Regulation, Current: 1mA
- Dimensions: 19" L x 21" W x 12" H
