ESP Solar Flare Model

1
ESP Solar Flare Model

• The Problem
• The ESP Model of Solar Protons
• 11 Year Average Proton Flux

Tom Diehl 06/30/2004
2
Solar Cycle Projection

• NGST Radiation Environmrnt Barth, Isaacs, Poivey
  http//www.ngst.nasa.gov/public/unconfigured/doc_0
  570/rev_04/ngstradenv2.pdf

• Solar flares and coronal mass ejections originate
  with the sunspots
• Plot on left is projected sunspot count.
• See large variation in solar activity.

Est. Sunspot Activity vs. Year (2009-2020)
3
The Problem

• Creme96 simulation provides
• Galactic cosmic ray fluences at solar minimum and
  solar maximum
• Worst 5 minutes, day, week of solar flares
• These are the extrema and the expected radiation
  dose varies from 7 rads/yr to 200 rad/day.
• We need a better model if we are to provide a
  spec. for radiation dose.

4
Emission of Solar Protons Model

• I came across it in an NASA memo The Radiation
  Environment GOES-R Series Satellites,
  417-R-RPT-0027 (March 2004) and in NGST radiation
  estimates, both by Janet Barth and Mike Xapsos.
• They referenced their model. http//trs.nis.nasa.g
  ov/archive/00000505/01/tp209763.pdf has the
  write-up and http//see.msfc.nasa.gov/ire/model_es
  p.html provides a link to software distribution.

5
ESP Model Results

• Input Ranges 1970-2020 and 50-99
• Results from 1970 to 1999 are based on actual
  observations.
• Results from 2000 on are averaged over previous
  years in the solar cycle.

6
ESP Model Results

• Four part output Proton Flux vs. C.L. for
  several C.L. and also the user C.L., same for
  worst case solar event.
• Energy range is 1 MeV to 300 MeV (k.e.)

2 // TYPE (1Input,2Output) 1998,1999,90
//INPUTS (Start Year,End Year,Confidence
Level) TOTAL PROTON FLUENCE FOR MISSION Results
for a mission of 1998 to 1999.(2 Active Years)  
GENERAL CONFIDENCE LEVEL
TABLE --------------------------------------------
----------------------
Integral Proton Fluence(cm-2) Energy Levels
Confidence Levels() (gtMeV)
80 85 90 95
99 ------------- ---------
--------- --------- --------- ---------
1 2.44E011 2.89E011 3.56E011
4.85E011 8.68E011 3
8.62E010 1.02E011 1.27E011 1.74E011
3.17E011 5 5.09E010
6.16E010 7.82E010 1.11E011 2.16E011 .
. . . .
. . . . .
. . . . .
. . . 275
2.03E007 3.02E007 4.97E007 1.04E008
4.19E008 300 1.59E007
2.37E007 3.91E007 8.20E007 3.29E008  
7
Proton Flux 2004-2015

• ESP Model provides solar proton flux estimates in
  energy range 1 to 300 MeV at distance averaged at
  1 A.U.
• Provides any combination of years from 1988xx to
  2020 and 50 or higher c.l. flux.

8
ESP Model - Plan

• Incorporporate this flux into MARS
• Get an update of the model from Mike Xapsos that
  goes to higher energy
• Overnighter to IEEE conference in Atlanta Ive
  arranged to meet M.X.

9
Summary

• Obtained ESP Model used by experts to simulate
  proton fluences from solar events in radiation
  damage simulations for satellites at L2.
• It solves the extrema problem and will allow us
  to make reasonable estimates of the doses.
• I plan to obtain an extension to the model from
  the authors.