Time-Domain EM (simpeg.electromagnetics.time_domain)

The time_domain module contains functionality for solving Maxwell’s equations in the time-domain for controlled sources. Here, electric displacement is ignored, and functionality is used to solve:

\[\begin{split}\begin{align} \nabla \times \vec{e} + \frac{\partial \vec{b}}{\partial t} &= -\frac{\partial \vec{s}_m}{\partial t} \\ \nabla \times \vec{h} - \vec{j} &= \vec{s}_e \end{align}\end{split}\]

where the constitutive relations between fields and fluxes are given by:

• \(\vec{j} = \sigma \vec{e}\)

• \(\vec{b} = \mu \vec{h}\)

and:

• \(\vec{s}_m\) represents a magnetic source term

• \(\vec{s}_e\) represents a current source term

Simulations

Simulation1DLayered([survey, time_filter])	Simulation class for simulating the TEM response over a 1D layered Earth for a single sounding.
Simulation3DMagneticFluxDensity(mesh[, ...])	3D TDEM simulation in terms of the magnetic flux density.
Simulation3DElectricField(mesh[, survey, ...])	3D TDEM simulation in terms of the electric field.
Simulation3DMagneticField(mesh[, survey, ...])	3D TDEM simulation in terms of the magnetic field.
Simulation3DCurrentDensity(mesh[, survey, ...])	3D TDEM simulation in terms of the current density.

Receivers

receivers.PointElectricField([locations, ...])	Measure TDEM electric field at a point.
receivers.PointCurrentDensity([locations, ...])	Measure TDEM current density at a point.
receivers.PointMagneticFluxDensity([...])	Measure TDEM magnetic flux density at a point.
receivers.PointMagneticFluxTimeDerivative([...])	Measure time-derivative of magnetic flux density at a point.
receivers.PointMagneticField([locations, ...])	Measure TDEM magnetic field at a point.
receivers.PointMagneticFieldTimeDerivative([...])	Measure time-derivative of magnet field at a point.

Waveforms

sources.StepOffWaveform([off_time])	A heavy-side step function waveform.
sources.RampOffWaveform([off_time])	A waveform with a linear ramp-off.
sources.RawWaveform([off_time, ...])	A waveform you can define.
sources.VTEMWaveform([off_time, peak_time, ...])	A VTEM style waveform
sources.TrapezoidWaveform(ramp_on, ramp_off)	A waveform that has a linear ramp-on and a linear ramp-off.
sources.TriangularWaveform(start_time, ...)	TriangularWaveform is a special case of TrapezoidWaveform where there's no pleateau
sources.QuarterSineRampOnWaveform(ramp_on, ...)	A waveform that has a quarter-sine ramp-on and a linear ramp-off
sources.HalfSineWaveform(ramp_on, ramp_off, ...)	A waveform that has a quarter-sine ramp-on and a quarter-cosine ramp-off.

Sources

sources.MagDipole([receiver_list, location, ...])	Point magnetic dipole source calculated by taking the curl of a magnetic vector potential.
sources.CircularLoop([receiver_list, ...])	Circular loop magnetic source calculated by taking the curl of a magnetic vector potential.
sources.LineCurrent([receiver_list, ...])	Line current source.
sources.RawVec_Grounded([receiver_list, s_e])

Surveys

survey.Survey(source_list, **kwargs)

Time domain electromagnetic survey

Fields

Fields3DMagneticFluxDensity(simulation)	Fields class for storing 3D total magnetic flux density solutions.
Fields3DElectricField(simulation)	Fields class for storing 3D total electric field solutions.
Fields3DMagneticField(simulation)	Fields class for storing 3D total magnetic field solutions.
Fields3DCurrentDensity(simulation)	Fields class for storing 3D current density solutions.

Base Classes

receivers.BaseRx(locations, times[, ...])	Base TDEM receiver class
sources.BaseWaveform([has_initial_fields, ...])	Base class for creating a waveform for time-domain EM simulations.
sources.BaseTDEMSrc([receiver_list, ...])	Base TDEM source class
simulation.BaseTDEMSimulation(mesh[, ...])	Base class for quasi-static TDEM simulation with finite volume.
fields.FieldsTDEM(simulation)	Base class for storing TDEM fields.
fields.FieldsDerivativesEB(simulation)	Field class for stashing derivatives for EB formulations.
fields.FieldsDerivativesHJ(simulation)	Field class for stashing derivatives for HJ formulations.