ESP Solar Flare Model The Problem The ESP

ESP Solar Flare Model • The Problem • The ESP Model of Solar Protons • 11 Year Average Proton Flux Tom Diehl 06/30/2004

Solar Cycle Projection • NGST Radiation Environmrnt: Barth, Isaacs, Poivey http: //www. ngst. nasa. gov/public/unconfigured/doc_0 570/rev_04/ngstradenv 2. pdf Est. Sunspot Activity vs. Year (2009 -2020) • Solar flares and coronal mass ejections originate with the “sunspots” • Plot on left is projected sunspot count. • See large variation in solar activity.

The Problem • Creme 96 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.

“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. gov/archive/00000505/01/tp 209 763. pdf has the write-up and http: //see. msfc. nasa. gov/ire/model_esp. html provides a link to software distribution.

ESP Model & Results • Input Ranges 19702020 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.

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 Me. V to 300 Me. V (k. e. ) 2 // TYPE (1=Input, 2=Output) 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() (>Me. V) 80 85 90 95 99 --------- --------- 1 2. 44 E+011 2. 89 E+011 3. 56 E+011 4. 85 E+011 8. 68 E+011 3 8. 62 E+010 1. 02 E+011 1. 27 E+011 1. 74 E+011 3. 17 E+011 5 5. 09 E+010 6. 16 E+010 7. 82 E+010 1. 11 E+011 2. 16 E+011 . . . 275 2. 03 E+007 3. 02 E+007 4. 97 E+007 1. 04 E+008 4. 19 E+008 300 1. 59 E+007 2. 37 E+007 3. 91 E+007 8. 20 E+007 3. 29 E+008

Proton Flux 2004 -2015 • ESP Model provides solar proton flux estimates in energy range 1 to 300 Me. V at distance averaged at 1 A. U. • Provides any combination of years from 1988 xx to 2020 and 50% or higher c. l. flux.

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; I’ve arranged to meet M. X.

Summary • Obtained “ESP Model” used by experts to simulate proton fluences from solar events in radiation damage simulations for satellites at L 2. • 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.