# Presentation: 722864

## D.H. BRAUTIGAM
SPACE VEHICLES DIRECTORATE
AIR FORCE RESEARCH LABORATORY

**AFRL**
**Electron Radiation Belt Models** **and Data Sets**

**Working Group Meeting on New Standard Radiation Belt and Space Plasma Models for Spacecraft Engineering**
**Greenbelt, MD**
**5-8 October 2004**** **

**D.H. BRAUTIGAM**
**SPACE VEHICLES DIRECTORATE**
**AIR FORCE RESEARCH LABORATORY**

## Outline

** ****CRRES**
** ****0.1 to 1.5 MeV - MEA (Aerospace, A.Vampola)**
** ****1.6 to 7.5 MeV : HEEF (AFRL)**
** ****CRRESELE – outer zone Ap-dependent model**
** ****Question of inner zone**
** ****TSX5/CEASE telescope **

## HEEF

-  2 SSDs
-  BGO crystal
-  active anti-coinc shield
-  very clean of protons
-  small GF
-  T- dependent BGO
-  SSDs paralyzed by intense low E e (~200 keV)

**HEEF**

## HEEF

- Channel Energy (MeV)
- 0.50 - 0.80: 0.65
- 0.85 -1.05 : 0.95
- 1.25 -1.70 : 1.60
- 1.70 - 2.10 : 2.00
- 2.10 - 2.50 : 2.35
- 2.50 - 2.90 : 2.75
- 2.90 - 3.30 : 3.15
- 3.30 - 4.10 : 3.75
- 4.10 - 4.95 : 4.55
- 4.95 - 6.60 : 5.75

**HEEF**

## CRRES/HEEF Survey

**CRRES/HEEF Survey**

**25 July 1990 - 12 October 1991**

## CRRESELE Model

**CRRESELE Model**
**At Solar Max**

-  binned in :
-  energy, p.a.
-  L, L>2.5
-  B/Bo
-  mapped to equator
-  equatorial distributions mapped along field lines
-  models:
-  activity (Ap) dependent
-  average
-  worst case

## Investigation of Inner Zone electrons

- CRH =  jp(E) RHp(E) dE
- CRL =  je(E) RLe(E) dE +  jp(E) RLp(E) dE

**Investigation of Inner Zone electrons**
**(is there a need to better specify this population?)**

- Predicted count rate (CR) in HiLET(H) and LoLET(L) channels is given by convolving the relevant  spectra with the relevant response curves
- Electron spectrum (je) and proton spectrum (jp) must be consistent between observed CR and “known” response

## Preliminary look at

- orbits 1-400, L=1.6 +/- 0.05 Re, +/- 5o MLAT

**Preliminary look at**
**Inner Zone electron spectrum**

- Average PROTEL spectrum is well fit to power law. Electron spectra from MEA, HEEF, and AE8MAX show large discrepancies

## Inner Zone electron spectrum

- (a) CRL =  je(E) RLe(E) dE +  jp(E) RLp(E) dE
-  	predicted CR (red-750; blue-158); observed CR (355)
- (b) CRL =  je(E) RLe(E) dE +  jp(E) RLp(E) dE
-        predicted CR (red-350), observed CR (355)

- orbits 1-400, L=1.6 +/- 0.05 Re, +/- 5o MLAT

**Inner Zone electron spectrum**

- (a)

- (b)

## TSX5 Launch / Orbit 

**TSX5 orbit: 410 x 1710 km, 69****o**** inclination**
**07 June 2000 - present**

- AE8max, >1.2 MeV

- CEASE, >1.2 MeV

## Compact Environmental Anomaly Sensor (CEASE)

**Telescope**
** ****>55 keV - >600 keV e**
** ****>4 MeV - >70 MeV p**

**Dosimeters**
** ****D1: >1 MeV e;  >20 MeV p**
** ****D2: >3 MeV e; >37 MeV p**

**Physical Specifications**
**  ****Mass:    1 kg****	**
**  ****Power:  1.2 W**
**  ****Size:     10 x 10 x 8 cm****3**

## CEASE Channels

**CEASE Channels**

## CEASE Calibration

**CEASE Calibration**

## Standard CEASE channels

| Channel | Electron
(MeV) |
| --- | --- |
| D1 (e) | >1.2 |
| D2 (e) | >3.2 |
| T1 (e) | >0.06 |
| T2 (e) | >0.12 |
| T3 (e) | >0.30 |
| T4 (e) | >0.55 |

**Standard CEASE channels**

## Solar Cycle Phases(estimates)

- NASA/NSSTC/Hathaway

**Solar min ****:**** ****Rise**** ****:**** Solar max ****: ****Decline ****:**** ****Solar min****     **

**Solar max**
-   Greatest frequency of solar proton events
**Declining phase**
-  High speed solar wind streams (HSSWS) – most intense outer zone electrons
**Solar min**
-  Lowest frequency of solar proton events

**TSX5****      **

**Notes:**
Solar wind plasma – outer part of sun’s corona streaming outwards, engulfing the earth’s magnetosphere
	characterized by : temperature, bulk flow speed, density

Interplanetary magnetic field – since the conductivity of solar wind is extremely high, the sun’s magnetic field is “frozen in” and flows with plasma

Coronal holes – shown in above figure as black region at north pole of sun – source of high speed solar wind streams 
High-speed corotating streams may persist from months to ~year, responsible for recurrent geomagnetic storms that characterize the declining phase of sunspot cycle .
These streams originate from the low temperature, open magnetic field regions known as coronal holes

Around solar max, coronal holes have greatly diminished in size, or else virtually disappeared.
During the declining phase towards solar min, the coronal holes re-emerge and develop in size, extending towards the equator, leading to well ordered high speed solar wind streams

## Mission Survey

**2001**

**2002**

**2003**

**2004**

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**Notes:**
Episodic nature of electron events

Slot region

Constancy of inner zone proton belt

First half : ~12 Solar protons events

Second half of mission much more frequent occurrence of intense episodes

Define Epoch 1 and Epoch 2 for this mission based upon solar proton event frequency and electron episode frequency
6/7/00 – 9/30/02		10/1/02 – 3/6/04
160/00-269/02		270/02-65/04
160-1000			1001-1526

Relate to solar wind, interplanetary conditions

## >0.12 MeV electron models

**>0.12 MeV electron models**

- Average flux profile for various time intervals

- Average flux within spatial interval L=2-3

## >1.2 MeV electron models

- Average flux profile for various time intervals

- Average flux within spatial interval L=2-3

**>1.2 MeV electron models**

## “Slot” Flux Cumulative Probability Distribution

**Probability that a given average flux level within the “slot” region (L=2-3) will be exceeded **