How do I solve an electron density continuity equation for Earth's atmosphere?

AI Thread Summary
The discussion focuses on solving a continuity equation for electron density in the E-region of Earth's atmosphere, specifically neglecting vertical transport and considering the ion production rate ceases at dusk. The equation presented is a Riccati equation, which can be expressed as dNe/dt = p(t) - αdNe². The user seeks guidance on integrating this equation with an initial electron density of approximately 1*10^9 m³. A correction is noted regarding a typo in the equation, clarifying that αd should be used instead of ad. The conversation emphasizes the need for understanding the integration of Riccati equations for accurate solutions.
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Homework Statement


Hi!

I need to solve a continuity equation for electron density as a function of time in the E-region of Earth's atmosphere. I shall neglect vertical transport and that the ion production rate completely shuts off dusk.

Homework Equations


See below

The Attempt at a Solution


Here is my attempt:

(1+λ)dNe/dt=p(t)-(1+λ)(αd-aλi)Ne2-Ne dλ/dt
Ne is the electron density, dy, λ=ratio of negative ions to electrons , p(t) is the electron production rate, αd is the recombination coeff. for ions and ai is the recombination coeff. negative ions with positive ions.

The effective recombination coefficient is: αeff=(1+λ)(αd+aλi).
If we assume that the is no negative ions, we get:
dNe/dt=p(t)-adNe2 (1)
and aeff simply becomes ad

Here comes the issue, I need to have a solution for equation (1) with respect to the density and time. . How should I integrate this? The density from the beginning is ≈ 1*109 m3 , which I calculated
 
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There is a typo in equation ##(1)##. If I understand correctly you meant to write ##\alpha_d## not ##a_d##.

Equation ##(1)## has the form of a Riccati equation:

$$\frac{dN_e(t)}{dt} = p(t) - \alpha_d N_e^2(t)$$
$$y'(t) = p(t) + g(t)y(t) + f(t)y^2(t)$$

Where ##N_e(t) = y(t)##, ##p(t) = p(t)##, ##g(t) = 0##, and ##f(t) = \alpha_d##.

To learn how to deal with equations of this form, see: https://en.wikipedia.org/wiki/Riccati_equation#Reduction_to_a_second_order_linear_equation
 
Zondrina said:
There is a typo in equation ##(1)##. If I understand correctly you meant to write ##\alpha_d## not ##a_d##.

Equation ##(1)## has the form of a Riccati equation:

$$\frac{dN_e(t)}{dt} = p(t) - \alpha_d N_e^2(t)$$
$$y'(t) = p(t) + g(t)y(t) + f(t)y^2(t)$$

Where ##N_e(t) = y(t)##, ##p(t) = p(t)##, ##g(t) = 0##, and ##f(t) = \alpha_d##.

To learn how to deal with equations of this form, see: https://en.wikipedia.org/wiki/Riccati_equation#Reduction_to_a_second_order_linear_equation
THANK YOU THANK YOU THANK YOU!
 
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