ESP & Psychic Solar Flare Models

• The Problem

• The ESP Model of Solar Protons

• Psychic Model

Tom DiehlJanuary 5, 2005

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 (from galactic protons) to 200 rad/day (from the worst solar flare).

• We need a better model if we are to provide a spec. for radiation dose.

Solar Cycle Projection

• NGST Radiation Environment: Barth, Isaacs, Poivey http://www.ngst.nasa.gov/public/unconfigured/doc_0570/rev_04/ngstradenv2.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.

• There’s an 11Yr solar cycle.

“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/tp209763.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 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.

Simple Interface:

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.) – The 100 to 300 MeV part is an extrapolation.

2 // TYPE (1=Input,2=Output)1998,1999,90 //INPUTS (Start Year,End Year,Confidence Level)TOTAL PROTON FLUENCE FOR MISSIONResults for a mission of 1998 to 1999.(2 Active Years)  GENERAL CONFIDENCE LEVEL TABLE------------------------------------------------------------------ Integral Proton Fluence(cm^-2)Energy Levels Confidence Levels() (>MeV) 80 85 90 95 99 ------------- --------- --------- --------- --------- --------- 1 2.44E+011 2.89E+011 3.56E+011 4.85E+011 8.68E+011 3 8.62E+010 1.02E+011 1.27E+011 1.74E+011 3.17E+011 5 5.09E+010 6.16E+010 7.82E+010 1.11E+011 2.16E+011 . . . . . .. . . . . .. . . . . . 275 2.03E+007 3.02E+007 4.97E+007 1.04E+008 4.19E+008 300 1.59E+007 2.37E+007 3.91E+007 8.20E+007 3.29E+008  

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 1988 to 2020 and 50% or higher c.l. flux.

• Plot is “Integral Flux”.

99

95

90

85

80

50

C.L. (%)

Integral Flux (> MeV)

Proton Flux 2004-2015• ESP Model• Differential spectrum

produced from the integral plot. The units are : #/cm2/yr at 50% C.L.

• Caveat: This ESP isn’t the Spenvis version. It’s the version I got from NASA.

Psychic Model• Update to ESP from

Mike Xapsos (NASA Goddard)– This guy is one of co-

authors of the model. I met him at the IEEE NSREC meeting in Atlanta in July.

– This update is called “Psychic” goes 327 MeV and has smoother differential spectrum.

Proton Flux – Psychic Model

• Average for 11 year cycle with 7 years at solar max and 4 years at solar min.

• # Protons above 11 51 100 MeV is: C.L. (%) #/cm2/s 50 93.9 7.8 1.3

• These are 2-3x higher than the ESP Model at k.e. > 50 MeV

ESP vs. Psychic

• Comparison based on 8 y @ solar max and 3 y @ solar min.

“MARS 15” and Psychic Results• NVM inc. made a new MARS release in

November.• I picked that up, incorporated the SNAP

model and reproduced the previous results.• I ran 20M “Psychic protons” using the

average flux from 7 yrs of solar max and 4 years of solar min.

• The silicon received a dose of 0.1 Rad/yr.

Summary and Plan

• Solar proton model from Mike X. provides solution. Dose was negligible.– Check MARS result

• Email to Mike X. with ESP vs. Psychic comparison

• Possibly this doesn’t include solar “events”.

• Implement the flux from the ESP Model.

• Write up results. Est. Feb 16.