@Bob
Hi Bob,
Am I correct that what we often see depicted as the ‘PEMF waveform’ is the generator’s voltage vs time driving the coils ? If so, since these voltages are directly proportional to the current they produce in the coils, the ‘PEMF waveform’ represents the B-field varying with time.
If this is incorrect please help me out and skip the rest
If this is correct I’m afraid we have a source of confusion for the PEMF community in general, since it doesn’t show us what the real agent in our tissues, the induced E-field, is doing.
As an example of this potential confusion take a triangular ‘PEMF waveform’ depicted with equal rise and fall time and furthermore only positive values. This waveform tells us that the current is swelling and diminishing, while only flowing in one direction. This one directional current produces a B-field which points in one direction (unipolar B-field), while its strength is growing and diminishing (i.e. it alternates between a positive and a negative slew rate value). Since the slew rate of a B-field is proportional to the induced E-field, the E-field changes its direction in a regular fashion (between clockwise and anticlockwise).
A most likely source of confusion in this case is that thinking in terms of a unipolar B-field might implicitly evoke a sense of a one directional effect in the tissues.
As a second example, if we would change our triangular waveform to be symmetric around the time axis (current flow now regularly alternating directions), the B-field would now regularly change polarity. If we make say the rising edge of this triangular waveform very shallow (i.e. B-field has a very low slew rate value there), the induced E-field for that edge becomes insignificantly small and we’re left with a virtually ‘unidirectional’ E-field, only exerting a significant force on ions in one direction (could be say ‘clockwise’). What could be a source of confusion here is that, seeing an alternating B-field depicted we’re tempted to think of an alternating effect in the tissues.
If the above is all correct, would this not suggest that talking about and/or depicting the induced E-fields (vs time) as ‘PEMF waveforms’, could greatly benefit the community’s thinking about PEMF ?