Principle

The DRUSCH NMR Gaussmeter measures magnetic fields with the help of nmr probes using the principle of nuclear magnetic resonance.

The meter's probe, which contains a small amount of resonant material, is placed inside the magnetic field to be measured. The resonant material is excited by a wide band variable high frequency wave. For frequency depending only on the magnetic field, an absorption resonance is generated.

The value of the magnetic field in question can be deduced from the measurement of this resonance frequency. The accuracy of the magnetic field measurement is dominated by the accuracy of the gyro magnetic ratio. For Hydrogen, which is used as resonant material for probes up to 2 Tesla, it is known with 4,25774 Gauss.

Thus, the absolute precision of the measurement is better than 10^-5. The relative precision, which pertains to the frequency measurement, is 10 times better, being in the order of 10^-6.

Description

The measurement unit consists of four elements:

• nmr probe
• pre amplifier
• cable, gaussmeter-pre amplifier
• nmr gaussmeter

NMR Probe

The probe is a box made of copper. At one extremity of the box a small cylinder with resonant material (sample) is located. On the other end of the box a flexible cable with a connecting plug to the preamplifier is attached. The resonance material interacts with the magnetic field to be measured.

Pre Amplifier

The pre amplifier is a small rectangle box with a socket on each front side - one output to the probe and the other to the gaussmeter. The pre amplifier shapes the resonance signal and conveys it to an appropriate level for transmitting to the gaussmeter.

Cable, gaussmeter-pre amplifier

The cable with a plug on each end connects the gaussmeter with the pre amplifier also over greater distances.

NMR Gaussmeter

The gaussmeter is a box made of aluminium, offered as 19" rack or portable version. On the front panel you will find the controls to adjust the measurement and the field display to display the measured signal. On the back panel the interfaces to the pc, oscilloscope and multiplexer as well as the mains connexion are situated. It is the unit, which drives the measurement process.