The Radiation Environment - NASA

1 J. Barth/Code 562 The Radiation EnvironmentSolar Protons&Heavier IonsGalactic Cosmic RaysTrapped ParticlesNikkei Science, Inc. of Japan, by K. EndoJ. Barth/Code 562 Components of the Natural EnvironmentuTransient Galactic Cosmic Rays Protons & Heavier Ions Solar Particle Events Protons & Heavier IonsuTrapped Electrons, Protons, & Heavier IonsuAtmospheric & Terrestrial Secondaries NeutronsJ. Barth/Code 562 Radiation & EffectsuTotal Ionizing Dose Cumulative long termionizing damage due toprotons & electronsuDisplacement Damage Cumulative long term non-ionizing damage due toprotons, electrons, &neutronsuSingle Event Effects Event caused by a singlecharged particle - heavy ions& protons for some devicesE.

2 Daly/ESAJ. Barth/Code 562 SunYohkoh/SXTS olarFlareuDominates theRadiationEnvironment Source ModulatoruStructure Photosphere Chromosphere CoronaJ. Barth/Code 562 Solar WinduStream of Charged Particles from Sun sCorona Electrons Protons Heavy IonsuMagnetized PlasmauDetected Out to 10 billion km from Earth byPioneer 10uVelocity ~ 300 - 900 km/suEnergy ~ .5 - keV/nucDensity ~ 1 - 30 / cm3}J. Barth/Code 562 Solar Wind Density & VelocityUniversity of Maryland, SOHO/CELIAS199723 Feb25 Feb27 Feb29 Feb1 Mar3 Mar5 Mar7 Mar300400500600510152025 Density (#/cm3)Velocity (km/s)J.

3 Barth/Code 562 MagnetosphereJ. Barth/Code 562 Coronal Mass EjectionsHolloman AFB/SOONuBubble of Gas &Magnetic FielduEjects ~1017 gramsof MatteruShock WaveAcceleratesParticles toMillions of km/hruAssociated withMagnetic StormsuProton Rich SolarEventsJ. Barth/Code 562 SOHO/LASCO During Solar Particle EventJ. Barth/Code 562 Solar FlaresuSudden BrighteningNear SunspotsuSolar System sLargest ExplosiveEventsuParticles AcceleratedDirectly by EventuHeavy Ion Rich SolarEventsJ. Barth/Code 562 Magnetic Stormsu Gusty Solar Wind Disturbs the CurrentSystems in the MagetosphereuMajor Storms Probably the Result of CMEs Must Be Pointed Toward Earth Strongest Arrive with Interplanetary MagneticField Oriented SouthuCause Increase in Rate & Intensity ofMagnetic Sub-storms in the GeotailJ.

4 Barth/Code 562 Electrical CurrentsDiscover Magazine - August 1995uNormal Conditions Currents Present on QuietDaysuStormy Conditions Intensified CurrentsJ. Barth/Code 562 Effects of Solar StormsuPower Black-outs on EarthuBlock Some Radio Communication Disturbs electrically charged gases in the ionosphereuInterfere with Cellular Phone Systems Ionospheric disturbances & satellite system failuresuInterfere with GPS Navigation (Ships & Airplanes)uTrigger Phantom Commands on SpacecraftuIncreased Atmospheric Drag on Low Earth Orbit (LEO)SatellitesuIncreased Protons & Heavy Ion Particle Countsu Pump Up the Van Allen BeltsJ.

5 Barth/Code 562161116212531161116212531 Solar Wind Velocity (IMP-8 MIT)SAMPEX Electrons E > 1 MeV Time of ANIK FailureANIK E1: Magnetic StormJanuary 1994 Velocity (km/s)Counts/s (x10)812345670200300800700400500600J. Barth/Code 562 AurorauParticles stream down onmagnetic field lines from thegeomagnetic tail forming anauroral beltuElectrons collide withatmospheric gasesuElectrons give energy to atomsand molecules which emitenergy as lightuOxygen ---> GreenuNitrogen ---> RedJ. Barth/Code 562 Aurora BorealisuNorthern lights ovalas measured byNOAA-14uCentered on MagneticPoleJ.

6 Barth/Code 562 Early Warning: S-CurvesuViewed with X-ray ImageryuBased on Two Years ofObservationsuStrong Correlation betweenSigmoid Regions and CMEsuLikely the Result of TwistedSolar Magnetic FieldsuMay Provide Early Warning ofParticle EventsMontana State UniversityJ. Barth/Code 562 Solar Activity: Cyclic VariationuSunspot Cycle Discovered in mid 1800suUsed as Indicator of Solar ActivityuIncreased Solar Activity Results in: Increased Rate of CMEs Increased Rate of Solar Flares Increased Rate of Magnetic Storms Increased Levels of Electrons in Van Allen Belts Decreased Levels of Protons in Van Allen Belts Increased Incidence of New Belt Formation Decreased Levels of Galactic Cosmic Rays Increased Rate of Solar Particle EventsuEffects on Climate?

7 J. Barth/Code 562 Sunspot Cycle17501800185019001950200005010015020 0250 Length Varies from 9 - 13 Years7 Years Solar Maximum, 4 Years Solar MinimumSunspot NumbersJ. Barth/Code 5621950196019701980199020000501001502002 50 Sunspot CycleSunspot NumbersCycle 18 Cycle 22 Cycle 21 Cycle 20 Cycle 19J. Barth/Code 5622040060801001930196019401950197019801 990150010020050 Sunspot Cycle with Magnetic StormsAnnual Number of Days with Ap>4 Sunspots & Magnetic Storm DaysAnnual Sunspot NumberSunspot Number# of Days with Ap > 4J. Barth/Code 562 Solar Cycle - Aurora DaysFrom Way North MagazineJ.

8 Barth/Code 562 Discovery of Galactic Cosmic Rays - 1913uElectroscope Experiments Dissipation of Charge on Leaves? Emissions from Materials on Earth Clean Instruments Did Not Eliminate DissipationuHess Balloon Experiments with Electroscopes Hypothesis: Background Radiation Will Disappear withIncreasing Altitude > 10,000 feet - Background Increased with Altitude Named Cosmic Rays by HessJ. Barth/Code 562 Galactic Cosmic Ray IonsuAll Elements in Periodic Table - 200 Million Years OlduEnergies in GeVuFound Everywhere in Interplanetary SpaceuOmnidirectionaluMostly Fully Ionized - Protons & Bare Nuclei of HeavierElementsuCyclic Variation in Fluence Levels Lowest Levels = Solar Maximum Peak Highest Levels = Lowest Point in Solar MinimumuTrajectories Bent by Magnetic FielduSingle Event Effects HazarduModel: CREME96J.

9 Barth/Code 56210203040506070809010010-210-110010110 21031041051061071081091010 GCRs: Nuclear CompositionRelative Flux (Si = 106)CNuclear Charge (Z)HHeOSiFeZrBaPtPbIndividual ElementsEven-Z ElementsElemental GroupsEnergy = 2 GeV/n, Normalized to Silicon = 106J. Barth/Code 562 GCRs: Solar Modulation197519771979198119831985198719 8919911993199510-510-410-310-210-1100101 102 DateCNO (#/cm2/ster/s/MeV/n)CNO - 24 Hour Averaged Mean Exposure FluxEnergy = 25-250 MeV/n - IMP-8J. Barth/Code 56210-110010110210310410510-610-510-410- 310-210-1100101 Surface Incident100 mils ( mm) Al500 mils ( mm) AlGCRs: Shielded Fluences - FeParticles (#/cm2/day/MeV/n)Interplanetary, CREME 96, Solar MinimumEnergy (MeV/n)J.

10 Barth/Code 56210-110010110210310410510-610-510-410- 310-210-1 GEOGTOMEOEOSLEOGCRsGCRs: Shielded: Shielded Fluences Fluences - Fe - FeCREME 96, Solar Minimum, 100 mils ( mm) AlEnergy (MeV/nuc)Particles (#/cm2/day/MeV/nuc)J. Barth/Code 562 Solar Particle EventsuIncreased Levels of Protons & Heavier IonsuEnergies Protons - 100s of MeV Heavier Ions - 100s of GeVuAbundances Dependent on Radial Distance from SunuPartially Ionized - Greater Ability to PenetrateMagnetosphereuNumber & Intensity of Events Increases DramaticallyDuring Solar MaximumuModels Dose - SOLPRO, JPL, Xapsos/NRL Single Event Effects - CREME96 (Protons & Heavier Ions)J.