Does the Debye Length Change with Applied Potential Strength in a Plasma?

In summary, the Debye length is the effective length over which electrostatic potential disturbances are "screened out" in a plasma. It is independent of the strength of the applied potential, but a stronger potential will penetrate farther into the plasma, requiring more Debye lengths for it to decay away. Adding a larger charge to the plasma will not increase the Debye length, but rather attract more ions/electrons within the existing Debye length.
  • #1
Sharkey4123
8
0
The debye length is the effective length over which electrostatic potential disturbances are "screened out" in a plasma.

So if I drop a charged point particle in a plasma, then I expect after some Debye Length, D, from this point charge, I can see no difference between any other point in the plasma.

Now, if I were to increase the charge of that particle and drop it in the plasma again, would the Debye length still be the same as before? Even if I considered this new charged particle to have any arbitrarily large charge?

Surely, the electrostatic potential created by this new charge would be much larger than the previous case, and thus "extend" further, taking "more" of the plasma to screen it out, hence a larger Debye Length. Is this correct?
 
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  • #2
I've probably figured this out myself, but should this be of use to anyone I'll leave it here for reference, or someone can correct me.

I believe that if I were to add a larger charge, there would simply be more ions/electrons (depending on the sign of the charge) attracted to within the Debye length.

So instead of an "increased" Debye length, I'd have more of the appropriate particle within the Debye length.
 
  • #3
Roughly speaking if you apply a potential to a plasma then the potential in a plasma will decay as [itex] \phi_0 e^{-\frac{\left|x\right|}{\lambda_D}} [/itex] where [itex] \lambda_D[/itex] is the Debye length and [itex] \phi_0[/itex] is the applied potential.

The Debye length is a measure of how fast the applied potential decays. It is independent of the strength of the applied potential. It is the same if I apply a 1V potential or a 10V potential. However a larger potential will penetrate farther into a plasma. This isn't due to a change in the Debye length. You're just applying a stronger field so it takes more Debye lengths for it to decay away.
 

1. What is the Debye Length?

The Debye Length is a characteristic distance in a plasma that describes the scale at which charged particles interact with each other. It is defined as the distance at which the electric potential from a charged particle is reduced by a factor of e (the base of natural logarithm).

2. How is the Debye Length related to applied potential strength in a plasma?

The Debye Length is inversely proportional to the square root of the plasma density and directly proportional to the square root of the temperature. Therefore, as the applied potential strength increases, the temperature and plasma density may change, resulting in a potential change in the Debye Length.

3. Does the Debye Length always change with applied potential strength?

In most cases, the Debye Length will change with applied potential strength. However, in certain conditions where the plasma is highly ionized and the temperature is constant, the Debye Length may remain constant regardless of the applied potential strength.

4. How does the Debye Length affect plasma behavior?

The Debye Length plays a crucial role in determining the screening effect in a plasma. It determines the scale at which charged particles interact with each other and affects the overall dynamics of the plasma.

5. Can the Debye Length be measured experimentally?

Yes, the Debye Length can be measured experimentally using various techniques such as Langmuir probes, microwave interferometry, and laser scattering. These techniques provide information about the plasma density and temperature, which can then be used to calculate the Debye Length.

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