---
# System prepended metadata

title: Ionosphere
tags: [' ss', ' Ionosphere', ' ncu', Intro to Space and Engineering]

---

---
tags: Intro to Space and Engineering, ss, ncu, Ionosphere
author: N0-Ball
GA: UA-208228992-1
---

# Ionosphere

## upper atmosphere

![](https://i.imgur.com/JZLNLq1.png)

- Lower domain
    - turbulent
    - various atomic and molecular
    - mixed
- molecular diffusion 
    - region extends from 110 to 500 km
    - = ionosphere and atmosphere
- higher altitude
    - long collisional mean-free-path 
    - particles follow ballistec trajectories
    - some escape from the atmosphere
- Fluid approach in a rarefied gas
    - collisions occur frequently on spatial
    - time scales much smaller than those characterizing the phenomena of interest

$$ 
\lambda >> \lambda_c \\[1em]
\omega << v_c
$$

## Scale height

![](https://i.imgur.com/pVjFpep.png)

## Terrestrial ionosphere

![](https://i.imgur.com/b3oewEp.png)
![](https://i.imgur.com/INP7H7U.png)

## Plasma in Ionosphere

![](https://i.imgur.com/OHSvMHy.png)

- Production or destruction of ionization (photochemical)
- Movement of ionization (transport)

$$
\frac{\partial n_e}{\partial t} + \nabla \cdot (n_e v_e) = P_e - L_e
$$

![](https://i.imgur.com/SIp8ss4.png)

## Production mechanisms for electrons 

### Photoionization

![](https://i.imgur.com/szD3MJj.png)

- absorption at least in low and mid-latitudes
    - solar Extreme UltraViolet (EUV)
    - X-ray
- Photons greater than about 12 eV(100nm within EUV) can ionsize the major atmospheric constituents
- Provides **heat input** 
    - maintain high temperatures of thermosphere
- excess energy -> kinetic energy of ion-electron pair
- transformed to heat upon recombination

### Energy sources and sinks

- EUV radiation
- particle 

ex.
$$
NO_2 + hv \rightarrow NO + O
$$

![](https://i.imgur.com/dS6ExBS.png)

## Solar spectrum 

![](https://i.imgur.com/nZe3ZkQ.png)

### X-rays
 - wavelength range of $10 < \lambda \le 0.01nm$
 - Hard X-ray
     - wavelength range of $1nm > \lambda (> 1.2 keV)$
 - Soft X-ray
     - wavelength range of $10nm > \lambda \ge 1nm$
     - XUV

### Ultraviolet 
- wavelength range of $400 < \lambda \le 10nm$
- Extreme Ultraviolet
    - EUV
    - wavelength range of $100nm > \lambda \ge 10nm$
- Vacuum Ultraviolet
    - VUV
    - wavelength range of $200nm > \lambda \ge 10nm$
- Ultraviolet 
    - UV
    - wavelength range of $400nm > \lambda \ge 100nm$

## Chapman layer

![](https://i.imgur.com/nwLG8LD.png)

**Thereotical**
![](https://i.imgur.com/Ff8b1Hg.png)

## Photoionaization


- F region
    - EUV (17 - 19.1nm)
    - *O* ionized by $\lambda < 91.1nm$
        - $O + hv \rightarrow O^+ + e^-$
    - *N~2~* ionized by $\lambda < 79.6nm$
        - $N_2 + hv \rightarrow N_2^+ + e^-$
- E region
    - EUV (91.1 - 102.7nm)
    - *O_2* ionized by $\lambda < 102.7nm$
        - $O_2 + hv \rightarrow O^+ + e^-$
    - X-rays (1 - 17nm)
- D region
    - EUV Ly-$\alpha$ 121.6 nm ionizes *NO*
        - $NO + hv \rightarrow NO^+ + e^-$
    - X-rays (0.1 - 1nm)

### Loss eactions of ions

- Ion-ion recombination
    - $X^+ + Y^- \rightarrow X + Y$
- Electron-ion recombination
    - $X^+ + e^- +M \rightarrow X + M$
    - $X^+ + e^- \rightarrow X^* + hv$
    - $\mathbf{XY^+ + e^- \rightarrow X^* + Y^*}$
- Ion-neutral (atom or molecule) interchange
    - $\mathbf{X^+ + YZ \rightarrow XY^+ + Z}$
    - $X^+ + YZ \rightarrow YZ^* + X$
- Collisional detachment (three body attachment)
    - $X^- + M \rightleftharpoons X + e^- + M$
    - $X^- + M^* \rightarrow X + e^- + M$
- Associative detachment (dissociative attachment)
    - $X^- + Y \rightleftharpoons XY + e^-$
- Photo-detachment (radiative attachment)
    - $X^- + hv \rightleftharpoons X + e^-$

## Topside Ionosphere

- Above F2 layer peak (atmospheric density is too low)
    - chemical recombination become less important
    - diffusive time constant becomes smaller than chemical time constant
- Below 
    - chemical recombination and transport are equally important
- Dominated by *O^+^*
- Exosphere
    - Dominated by *H^+^*

## F region

- altitudes > 200km
- principal ion formed is *O^+^* By EUV (17-91.1 nm)
    - $O + hv \rightarrow O^+ + e^-$
    - at $\lambda < 91.1nm$
- *O^+^* loss process is **Radiative recombination**
    - extremely low reaction rate
    - $O^+ + e^- \rightarrow O + hv$
    - $k = 3 \times 10^{-12} cm^3s^{-1}$
    
### ion-atom interchange

- recombination ($\beta$ loss)
    - $O^+ + O_2 \rightarrow O_2^+ + O$ 
        - k = 2x10^-11^
    - $O^+ + N_2 \rightarrow NO^+ + N$
        - k = 1x10^-12^
- dissociative recombination ($\alpha$ loss)
    - $O_2^+ + e^- \rightarrow O + O$
    - $NO^+ + e^- \rightarrow N + O$
        - k=3x10^-7^

## F1 region

- altitudes 140-200 km
- principal ion formed is *O^+^* By EUV (17-91.1 nm)
    - $O + hν \rightarrow O^+ + e^-$
    - at $\lambda < 91.1nm$
- with some contribution from
    - $N_2 + hν \rightarrow N_2^+ + e^-$
    - at $\lambda < 97.6nm$
        
## E region

- altitudes 90-140 km
- mainly produced from *O~2~* molecules by EUV (91.1-102.7 nm)
    - $O_2 + hν \rightarrow O_2^+ + e^-$
- Additional ionization of nitrogen molecules by coronal X-rays (1-17 nm)
    - $N_2 + hv \rightarrow N^+ + e^-$
    - $N_2^+ + O \rightarrow N + NO^+$
    - $N_2^+ + O_2 \rightarrow N_2 + O_2^+$

### The distinguishing feature between E and F1 layers 

- F1
    - Radiative recombination is extremely low
    - Must transfer their charge to molecules prior to recombination
- E
    - Directly recombination
    - Typically, the reaction rate is a factor of 100,000 smaller than the dissociate recombination process.