Magnetic Field Measurements

Comparison of EHT integrator output with in-house integrator output at a fusion science experiment

EHT integrators measure both extremely small fields and extremely large fields with high precision. For example, if connected to a loop with a 0.1 marea (100 turns 3 cm in diameter) wound on ferrite with a relative permeability of 1000, the integrator would produce a 1 mV output when measuring a 100 pT field. When measuring medium to large fields, small air core pickup coils would be used. Since air core coils do not suffer saturation issues, the EHT integrators can measure very large fields, for very long times, without the usual droop and saturation issues encountered when using standard current monitors/transformers. There is no inherent limit to the maximum field size that can be measured. Due to their extremely high gain and high frequency of operation, the integrators have an unprecedented effective dynamic range.

Low amplitude, high frequency oscillation measured on top of large slower magnetic field with a single coil and EHT integrator