Magnetic field cancelling system
SC22 Magnetic Field Cancelling System. High performance electron beam instruments are very sensitive to changing ambient magnetic fields.
High performance electron beam instruments are very sensitive to changing ambient magnetic fields. The fields move the beam causing loss of resolution and measurement accuracy. Fields which exceed the manufacturer's environmental specification are common, being created by nearby machinery and equipment as well as by external sources. Operation in such fields prevents the instrument from reaching its full performance.
Magnetic field cancelling systems provide an effective solution for dampening ambient magnetic fields, allowing high resolution performance of TEM, SEM and FEG SEM instruments. The system comprises of a magnetic field control unit, magnetic field sensor and three multicore cables. The cables are installed in the room on the X, Y and Z axes. The sensor measures the strength and phase of the field in real time. The signals are fed to the control unit where three power amplifiers drive anti-phase currents through the multicore cables to effectively nullify the field.
The SC22 system includes a magnetic field control unit, an AC magnetic field sensor and three multicore cables. It automatically responds to field changes within 100 µs. The SC22 does not cancel DC field changes from sources such as elevators, trains and traffic. For higher level fields, and where there is a DC component to the fields, the model SC20 should be chosen. The SC20 system can provide AC or DC cancelling depending on the sensors installed. It recognizes the sensors used and selects the internal filters. The sensor mixer function is built into the SC20 and becomes active when two sensors are plugged in.