Nereid said: If we can't agree - even in the limited discussion in this thread!- on what 'electrical currents' are....
Solrey said: Even our modern electronics are electrically neutral as a bulk system. Walking around with a cell phone stuck to ones head doesn't produce an electric current by the motion of the phone, nor is there any electrostatic potential between you and the phone, but inside the phone, the battery provides an internal electrostatic potential producing electric current in the conducting material of the circuitry.
Langmuir wrote:Except near the electrodes, where there are sheaths containing very few electrons, the ionized gas contains ions and electrons in about equal numbers so that the resultant space charge is very small. We shall use the name plasma to describe this region containing balanced charges of ions and electrons
Resolving field-aligned current morphology: FAST-THEMIS conjunctions
Strangeway, Robert J.
37th COSPAR Scientific Assembly. Held 13-20 July 2008, in Montréal, Canada., p.3049
Field-aligned currents (FACs) are quite often considered in isolation, somewhat separated from the sources and sinks for the FACs. When observed in the magnetosphere, FACs are viewed as being generated through divergence of perpendicular currents associated with pressure gradients or vorticity, usually without any consideration of how these FACs close in the ionosphere. At intermediate altitudes, on the other hand, the FACs may be identified with closure currents in the ionosphere (usually assumed to be Pedersen currents), but the connection to the sources of the currents in the magnetosphere is not addressed. Finally, for magnetic field observations below the ionosphere, it is typically assumed that the magnetic field perturbations are from Hall currents. With the THEMIS mission we are now in a good position to make connections between these separate viewpoints. In particular, the THEMIS spacecraft provide observations of the magnetospheric plasma and fields, the FAST spacecraft provides data from intermediate altitudes, and the THEMIS ground network provides observations of the ionosphere from below. Coupled with powerful global simulations we can provide definitive answers concerning the sources and sinks of FACs. One example that we have investigated with these resources is the Westward Traveling Surge (WTS) during the March 23, 2007 substorm interval. At THEMIS the passage of the WTS over the spacecraft is related to the magnetic field dipolarization, and hence the passage of an upward FAC. At FAST the WTS is observed as a flow channel bounded by a pair of FACs. The global simulations confirm that both FAST and THEMIS are observing the WTS, and the WTS is associated with a narrow flow channel. The implication is that while the magnetospheric signature of the WTS is an upward current, the ionospheric signature is more structured, with both upward and downward currents being observed, but with net upward current.
Jarvamundo wrote:Yep, i like it...
Wikipedia says: Because of collisions between electrons and atoms, the drift velocity of electrons in a conductor is on the order of millimeters per second. However, the speed at which a change of current at one point in the material causes changes in currents in other parts of the material, the velocity of propagation, is typically about 75% of light speed.[118] This occurs because electrical signals propagate as a wave, with the velocity dependent on the dielectric constant of the material.[119]
Anaconda wrote:On a side note, Since David Talbott mentioned the acceleration of the solar wind, I thought linking a peer-reviewed published paper on solar wind acceleration might be appropriate:
Acceleration of the solar wind, Egil Leer, Thomas E. Holzer and Tor Flå, published in Space Science Reviews:
http://www.springerlink.com/content/l72q04465w270073/
This paper, beyond discussing the acceleration of the solar wind, also notes that charged particles flow out from the surface of the Sun and INTO the surface of the Sun (noteworthy for discussion of the Electric Sun hypothesis).
Marsch wrote:
Solar Wind Models from the Sun to 1 AU: Constraints by in Situ and Remote Sensing Measurements
There are three major types of solar wind: The steady fast wind originating on open magnetic field lines in coronal holes, the unsteady slow wind coming probably from the temporarily open streamer belt and the transient wind in the form of large coronal mass ejections. The majority of the models is concerned with the fast wind, which is, at least during solar minimum, the normal mode of the wind and most easily modeled by multi-fluid equations involving waves. The in-situ constraints imposed on the models, mainly by the Helios (in ecliptic) and Ulysses (high-latitude) interplanetary measurements, are extensively discussed with respect to fluid and kinetic properties of the wind. The recent SOHO observations have brought a wealth of new information about the boundary conditions for the wind in the inner solar corona and about the plasma conditions prevailing in the transition region and chromospheric sources of the wind plasma. These results are presented, and then some key questions and scientific issues are identified.
Goldminer wrote:Consensus astronomy is all about gravity, shock waves, and wind.
The EU sees the "wind" as plasma.
What moves plasma? A potential difference.
Marsch wrote:
Solar Wind Models from the Sun to 1 AU: Constraints by in Situ and Remote Sensing Measurements
There are three major types of solar wind: The steady fast wind originating on open magnetic field lines in coronal holes, the unsteady slow wind coming probably from the temporarily open streamer belt and the transient wind in the form of large coronal mass ejections. The majority of the models is concerned with the fast wind, which is, at least during solar minimum, the normal mode of the wind and most easily modeled by multi-fluid equations involving waves. The in-situ constraints imposed on the models, mainly by the Helios (in ecliptic) and Ulysses (high-latitude) interplanetary measurements, are extensively discussed with respect to fluid and kinetic properties of the wind. The recent SOHO observations have brought a wealth of new information about the boundary conditions for the wind in the inner solar corona and about the plasma conditions prevailing in the transition region and chromospheric sources of the wind plasma. These results are presented, and then some key questions and scientific issues are identified.
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