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# Debye length, plasma frequency and cyclotron frequency

The calculation of characteristic Debye length, plasma frequency and cyclotron frequency of electrons in the ionosphere, the plasmasphere, the outer magnetosphere and the solar wind.

```clc;clear all;
me   = 9.109E-31;            %[kg]           Electron rest mass
mp   = 1.673E-27;            %[kg]           Proton rest mass
eps0 = 8.8542E-12;           %[A*s/(V*m)]    Permittivity
e    = 1.602E-19;            %[C]            Elementary charge
Re   = 6.37E6;               %[m]            Earth’s radius
Md   = 8E15;                 %[T*m3]         Earth’s magnetic dipole moment```

## Ionosphere

```n   = 1E12;                     %[m-3]  Electron density
kTe = 0.1;                      %[eV]   Thermal energy
r   = Re + 3E5;                 %[km]   Radial distance from the Earth’s center
wp  = (e^2*n/(eps0*me))^0.5/(2*pi);  %[Hz]   Plasma frequency
lD  = (eps0*kTe/(n*e))^0.5;     %[m]    Debye length
B   = 2*Md/r^3;                 %[T]    Earth’s magnetic field
Fc  = e*B/(2*pi*me);            %[Hz]   Cyclotron frequency
fprintf('Debye length        %4.2d [m]\n',lD);
fprintf('Plasma frequency    %4.2d [Hz]\n',wp);
fprintf('Cyclotron frequency %4.2d [Hz]\n\n',Fc);```
```Debye length        2.35e-003 [m]
Plasma frequency    8.98e+006 [Hz]
Cyclotron frequency 1.51e+006 [Hz]```

## Plasmasphere

```n   = 1E7;                      %[m-3]  Electron density
kTe = 1;                        %[eV]   Thermal energy
r   = 5*Re;                     %[km]   Radial distance from the Earth’s center
wp  = (e^2*n/(eps0*me))^0.5/(2*pi);  %[Hz]   Plasma frequency
lD  = (eps0*kTe/(n*e))^0.5;     %[m]    Debye length
B   = 2*Md/r^3;                 %[T]    Earth’s magnetic field
Fc  = e*B/(2*pi*me);            %[Hz]   Cyclotron frequency
fprintf('Debye length        %4.2d [m]\n',lD);
fprintf('Plasma frequency    %4.2d [Hz]\n',wp);
fprintf('Cyclotron frequency %4.2d [Hz]\n\n',Fc);```
```Debye length        2.35e+000 [m]
Plasma frequency    2.84e+004 [Hz]
Cyclotron frequency 1.39e+004 [Hz]```

## Outer magnetosphere

```n   = 1E6;                      %[m-3]  Electron density
kTe = 50;                       %[eV]   Thermal energy
r   = 7*Re;                     %[km]   Radial distance from the Earth’s center
wp  = (e^2*n/(eps0*me))^0.5/(2*pi);  %[Hz]   Plasma frequency
lD  = (eps0*kTe/(n*e))^0.5;     %[m]    Debye length
B   = 2*Md/r^3;                 %[T]    Earth’s magnetic field
Fc  = e*B/(2*pi*me);            %[Hz]   Cyclotron frequency
fprintf('Debye length        %4.2d [m]\n',lD);
fprintf('Plasma frequency    %4.2d [Hz]\n',wp);
fprintf('Cyclotron frequency %4.2d [Hz]\n\n',Fc);```
```Debye length        5.26e+001 [m]
Plasma frequency    8.98e+003 [Hz]
Cyclotron frequency 5.05e+003 [Hz]```

## Solar wind

```n   = 1E6;                      %[m-3]  Electron density
kTe = 5;                        %[eV]   Thermal energy
wp  = (e^2*n/(eps0*me))^0.5/(2*pi);  %[Hz]   Plasma frequency
lD  = (eps0*kTe/(n*e))^0.5;     %[m]    Debye length
B   = 1E-8;                     %[T]    Earth’s magnetic field
Fc  = e*B/(2*pi*me);            %[Hz]   Cyclotron frequency
fprintf('Debye length        %4.2d [m]\n',lD);
fprintf('Plasma frequency    %4.2d [Hz]\n',wp);
fprintf('Cyclotron frequency %4.2d [Hz]\n\n',Fc);```
```Debye length        1.66e+001 [m]
Plasma frequency    8.98e+003 [Hz]
Cyclotron frequency 2.80e+002 [Hz]```

1. David Fairbairn says:
• smallsat says: