Description
Determines when the spacecraft crosses into or out of a region with a certain level of flux. The ParticleFluxTimes method uses the NASA AP-8 and AE-8 particle flux maps to calculate the omnidirectional flux of the specified particle type with the energy level specified by minimumEnergy. The AP/AE maps contain collected data of proton and electron fluxes in the Earth's radiation belt with energy ranges from 0.04 MeV to 7 MeV for electrons and from 0.1 MeV to 400 MeV for protons. See the help file for links to more detailed documentation on the AP/AE maps. The user has the option to specify epoch and longitude offsets to include in the flux calculation.
Timing Precision Mode
This page describes functionality in nanosecond timing precision mode.
Click here to see the documentation for this object in millisecond timing precision mode.
Note: This is an interval method. See the Interval Methods page for more information.
Note: This method has a state. See the Methods and Properties with State page for more information.
Method Signature
Arguments
fluxThreshold
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Description:
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Flux threshold for which events should be reported.
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Units:
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particles/(cm2 s)
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Valid Range:
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fluxThreshold > 0
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minimumEnergy
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Description:
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Minimum energy of particles contributing to the flux. Energy values for Electrons range from 0.1 to 7.0 MeV; for Protons from 0.1 to 400.0 MeV.
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Units:
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MeV
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Valid Range:
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minimumEnergy > 0
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particleType
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Description:
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The type of particle for which flux will be computed.
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Valid Values:
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Value
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Label
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0
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electrons
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1
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protons
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solarActivity
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Description:
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The solar activity level of the flux model. The AP-8/AE-8 flux maps use the 1964 IGRF Magnetic Field model when modeling solar minimum, and the 1970 IGRF Magnetic Field model when modeling solar maximum.
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Valid Values:
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Value
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Label
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0
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solar minimum
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1
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solar maximum
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igrfEpochOffset
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Description:
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An offset added to the epoch of the IGRF Magnetic Field model, used to determine the epoch of the magnetic field. Generally this argument should be between 0 and 365, signifying the number of days after the base epoch of the Magnetic Field model.
The epoch of the IGRF Magnetic Field model, when modeling solar minimum, is Jan 01 1964 12:00:00.000.
The epoch of the IGRF Magnetic Field model, when modeling solar maximum, is Jan 01 1970 12:00:00.000.
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Units:
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day
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longitudeOffset
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Description:
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An offset added to the Longitude of the Spacecraft when computing the local magnetic field strength; the Latitude and Altitude are held constant. A positive offset is applied in the West direction.
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Units:
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deg
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Return Value
Returns a string containing the entrance or exit time for any flux threshold crossings.
The FF_Preferences.IntervalEventReportingBehavior property controls whether the start and end of propagation are reported as events. By default, if entry into high flux starts before the beginning of the propagation span, FreeFlyer will label the start of the propagation as the entry into high flux. If the time in high flux extends past the end of the propagation span, FreeFlyer labels the end of propagation as the exit from high flux.
Syntax
myString1 = mySpacecraft1.ParticleFluxTimes(myVariable1, myVariable2, myVariable3, myVariable4, myTimeSpan1, myVariable5);
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This example demonstrates how to generate a report of times when the calling Spacecraft enters and exits areas of high particle flux with epoch and longitude adjustments. The method returns the arguments used, entry and exit times, and duration in the area of high flux.
Spacecraft Spacecraft1;
Variable fluxThreshold = 5; // particles/(cm^2 s)
Variable minEnergy = 10; // MeV
Variable particleType = 1; // Protons
Variable solarActivity = 1; // Solar Maximum
Variable longitudeDrift;
TimeSpan epochDrift;
TimeSpan igrfModelEpoch = "Jan 01 1970 12:00:00.000".ParseCalendarDate();
epochDrift = TimeSpan.FromDays(Spacecraft1.Epoch.ConvertToCalendarDate("DOY.DDD").ToVariable() - 0.5);
// Calculate trapped particle belt drift. Particle belt drifts to the
// west at a rate of 0.27 degrees per year.
longitudeDrift = 0.27 * (Spacecraft1.Epoch - igrfModelEpoch).ToDays()/365;
While (Spacecraft1.ElapsedTime < TIMESPAN(1 days));
Report Spacecraft1.ParticleFluxTimes(fluxThreshold,
minEnergy,
particleType,
solarActivity,
epochDrift,
longitudeDrift) to "ParticleFluxEncounters.txt";
Step Spacecraft1;
End;
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Output:
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See also
Spacecraft Object
Spacecraft.ParticleFluxTimes
Spacecraft Propagation Guide
Coverage and Contact Analysis Guide
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