Confused about the Drude model

[chandrahas]

I was thinking about hall conductivity, when this question popped up. If there is a magnetic field and an electric field perpendicular to it, then a hall current is generated since the ions have larger gyro radii compared to electrons. Now this current would produce a J cross B force in the direction of Electric field. this means that if electrons have sufficient thermal energy in a plasma, they can create a current that pushes them in the direction of the electric field. This would result in negative conductivity if it is strong enough right?

But solving the drude model equation doesn't give us and negative conductivity anywhere.

So, I was wondering if the effect is not strong enough to result in negative conductivity or whether the drude model does not consider the J cross B force. I always thought the momentum- magnetic field cross product term was the J cross B force.

Thanks

 

[Baluncore]

Now this current would produce a J cross B force in the direction of Electric field. this means that if electrons have sufficient thermal energy in a plasma, they can create a current that pushes them in the direction of the electric field. This would result in negative conductivity if it is strong enough right?

The Drude model assumes a solid state. I would not apply the Drude model to a plasma. In a plasma you must use MHD analysis.
Hot electrons have a wider Gaussian velocity distribution. Only a few will be going against the flow, an equal number will be going faster by a similar amount.

 

[sophiecentaur]

an equal number will be going faster by a similar amount.

Oh, if only we could select those and use them.