ENTER THE INITIAL COORDINATES OF THE e- IN INCHES

Here you choose the coordinates of the DAi you desire, and enter them in units of inches/100.  That is, if the coordinates of my starting point are (-1.0466", -0.7236", -0.0888"), then one would enter for a reply -0.010466, -0.007236, -0.000888.

 

ENTER LOWER BOUND ON TIME (t = 0)

 

Reply:  0.0 (units of seconds)

 

ENTER UPPER BOUND ON TIME

 

This response depends on how far the particle has to travel to get out of the detector.  If the response is not large enough, the calculation stops before the particle has a chance to escape the system.  A reasonable value that works for all of the electron energies is t = .1 seconds or so.

 

ENTER THE TIME STEP

 

This response depends on how big a line segment you take from one step of the trajectory to the next.  The best thing to do here is to be reasonable.  You want a fairly smooth trajectory, but at the same time, you don't want the steps so small that it takes forever to execute the program.  I have found that the following values work fairly well for this simulation:

 

Time step = .0005 seconds for 20 keV<E<100 KeV,
Time step = .0002 seconds for 100 keV<E<500 keV.

 

My advice would be to experiment, starting with larger time steps and working my way down until npas remains the same.

 

ENTER THE ERROR BOUND

 

This parameter can really foul things up if too large or too small.  It enters in the differential equation solver TDHPCG.  A rough estimate is to simply take the error bound as (.05)x(time step), but (.10)x(time step) tends to give the same results.  In either case, it is important that the value for npas be as large as possible.  That is, repeat the simulation trying various values, and use those that give the maximum value for npas in the least amount of CPU time.  Experiment before doing a full blown calculation for all starting points!

 

ENTER MID THETA, THETAMAX, DEL THETA

 

These values depend on the geometry of your system.  You could scan over the full 4p globe, but this would not be very efficient.  There tends to be a range of values for theta and phi through which you will find all escaping trajectories.  This range depends on the starting coordinate and is energy dependent; again, it is in your best interest to experiment.  Refer back to your original geometry to help you establish some initial guesses for this range, and try them out.

 

ENTER MIN PHI, NO. OF STEPS, DEL PHI

 

Follow the above suggestions.

 

What results from a single run through the main program?  The answer is npas, the number of trajectories that escape the deflection system for a particular energy and starting coordinate.  Also produced are various output data files that list important information on the escaping trajectories.  See page 66 of Shodhan's thesis for more details.  Check these output files and make sure the data seems reasonable.

 

Once you are satisfied with the results of the main program, the idea is to rerun the program for all the starting coordinates for a particular energy.  My advice at this point is to create a command procedure program that types in all necessary information for you.  For example, when doing this simulation for HISCALE I chose 12 distinct energies at which I needed to determine G for this deflection system.  I modified TRAJ6PT to loop through all starting coordinates, as well as all 12 energies.  I then wrote a command procedure that fed in the necessary commands to execute the entire program.  A small clip of the command program SKIP.COM is shown in the listing of programs in the back.  These command procedures will save you a lot of time.

 

The results of the output file *.E*IN can be used to calculate G.  See program FACTORA listed in the back of this thesis.  Once you have G for the selected energy ranges you desire, you must next plot the results and estimate G for the energy passbands of the various channels of your instrument. A program entitled AREA does this calculation for you, and is included in the software package.

 

 

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Return to HISCALE List of Appendices

Return to Ulysses HISCALE Data Analysis Handbook Table of Contents

Updated 8/8/19, Cameron Crane

Manufacturer: ESA provided the Ulysses spacecraft, NASA provided the power supply, and various others provided its instruments.

Mission End Date: June 30, 2009

Destination: The inner heliosphere of the sun away from the ecliptic plane

Orbit:  Elliptical orbit transversing the polar regions of the sun outside of the ecliptic plane

• Ulysses Information at the Jet Propulsion Laboratory
• Ulysses Website at the European Space Agency