# ANSYS 14.5 and the Hall Coefficient RH

Does something written by a tech support engineer make you subconsciously start checking for misplaced commas? Does my motto  ”Close enough for highway work!” disqualify me, in your eyes, to talk about something as subtle as the Hall effect? I hope not, because if you bail out now you’ll miss the chance to find out about a completely new electrical material property in ANSYS 14.5, the Hall coefficient RH.  It will be supported initially by the EM elements SOLID236 and SOLID237 and eventually by the direct coupled field elements.

{EH} = –RH[{J}x{B}]  Hall Electric Field

The force produced by a magnetic field acting on a current (JxB) has been available in ANSYS software for decades, but not the transverse electric field it creates. This field was discovered by Edwin Hall in 1879 and is named after him. It’s very weak compared to the field that creates it, but strong enough to detect the passing of the pole of a motor, for example. Or a Hall sensor can wake up a smart phone when it’s removed from the case. For many applications, solid-state construction allows a Hall sensor to be used in hostile environments.

Because the Hall voltage must be induced by a field much stronger than itself, any bias in the sensor can distort the primary field and mask the hall field being sensed. Sources of such bias are manufacturing defects, temperature variation, and stress and deformation.  It would be possible to do an initial thermal analysis study to obtain the temperature variation in the sensor and then compute the Hall voltage based on temperature-dependent electrical resistivity (RSVX) and Hall coefficient (RH.)

It’s also important to check for any mesh bias in the finite element model by measuring the Hall voltage with no magnetic field (should be zero) to obtain a baseline value.

It would also be interesting to test the efficiency of different sensor shapes. The shapes below were all subjected to the same current and magnetic field. The “clover leaf” design produced the highest Hall voltage of the five, but also consumed the most power.