glyn_collinson:
Thank you for your response.
I appreciate your time & effort to participate and answer questions in this forum.
Here is the relevant part of your answer to my question:
Please, however, allow me a preamble, introductory statement, before providing the question & answer.
The presence of Double Layers and their physical dynamics in space plasma is a central thesis & proposition of this forum and when analyzing & interpreting astrophysical phenomenon, to arrive at a complete understanding of such astrophysical phenomenon, the identification of Double Layers is a first order of analysis & interpretation.
Indeed, the Electric Universe Theory, as a whole. rises or falls on the thesis & proposition that Double Layers are a wide-spread and common phenomenon in astrophysical plasmas.
The idea that Double Layers are wide-spread and common phenomenon in astrophysical plasmas was first proposed by Hannes Alfven, the 1970 Nobel Prize winner in physics for his work on magnetohydrodynamics (MHD).
With that preamble, onto the question & answer:
glyn_collinson wrote:Anaconda wrote:Does your paper recognize and discuss that where seperate bodies of plasma, with different physical properties, collide, a Double Layer will form?
... So, double layers form when you get areas of charge separation, so the ionosphere, for example, where the ions can penetrate further than the electrons. However, the solar wind is basically quasi-neutral (equal numbers of electrons and ions), so you won't see anything like that on large scales.
~Glyn
I respectfully disagree.
In brief, the formation of Double Layers do not depend on pre-existing charge seperation, rather, Double Layers form where bodies of plasma collide and, in turn, cause charge seperation, and, thus, segregated currents of electrons and ions.
Double Layers are the cause of charge seperation, their formation does not depend on a pre-existing state of charge seperation, but, rather, on the collision of plasma bodies with different physical properties -- charge seperation can be present, but is not a necessary prerequisite, for the formation of Double Layers in astrophysical plasma.
And, given the above preamble, it is important to state in precise terms why I disagree with your answer.
In regards to quasi-neutral plasma, it is important to remember, while the plasma has equal numbers of electrons & ions, it is still an ionized or an electrified body. Coulomb force is present among the free electrons & ions in a body of plasma.
Wikipedia entry wrote:Coulomb's law or Coulomb's inverse-square law is a law of physics describing the electrostatic interaction between electrically charged particles.
http://en.wikipedia.org/wiki/Coulomb's_law
Coulomb force is present in all plasmas -- or, in fact, it wouldn't be a plasma, but instead a body of neutral gas.
Given the above statement, one needs to be conscious of the physics of how a Double Layer forms in bodies of plasma:
Anthony L. Peratt provides a two-step statement of how Double Layers form in astrophysical plasma:
“The moving plasma, i.e., charged particles flows, are currents that produce self-magnetic fields, however weak.” — Dr. Anthony L. Peratt, Los Alamos National Laboratory, retired
“An electromotive force [mathematical equation] giving rise to electrical currents in conducting media is produced wherever a relative perpendicular motion of plasma and magnetic fields exists.” — Dr. Anthony L. Peratt, Los Alamos National Laboratory, retired
In other words, colliding bodies of plasma, yes, colliding quasi-neutral bodies of plasma, cause Double Layer boundary sheaths to form, which, then, in turn, causes the segregation and acceleration of charged particles, which are segregated into bodies of electrons & ions, thus, segregated electric currents.
Who is Dr. Anthony L. Peratt?
Peratt biography wrote:Anthony L. Peratt (S'60, M'63, SM'85, F'99) received his Ph.D. in electrical engineering in 1971 from the University of Southern California, Los Angeles. Earlier degrees include the MSEE, USC, 1967; UCLA, 1963-1964, BSEE, California State Polytechnic University. He was a Staff Member at Lawrence Livermore National Laboratory (1972-1979); a Guest Physicist at Max Planck Institut für Plasmaphysik, Garching, Germany (1975-1977); a Guest Scientist, Alfvén Laboratory of the Royal Institute of Technology in Stockholm, Sweden (1985); and, at Los Alamos National Laboratory from1981to the present serving in the Applied Theoretical Physics Division, Physics Division, Associate Laboratory Directorate for Experimental Programs; and as Scientific Advisor to the United States Department of Energy (1995-1999) where he served a term as Acting Director, National Security, in the Nuclear Nonproliferation Directorate.
Dr. Peratt's research interests have included numerical and experimental contributions to high-energy density plasmas and intense particle beams; explosively-driven pulsed power generators; lasers; intense-power-microwave sources; particles; high energy density phenomena, Z-pinches, and inertially driven fusion target designs.
He has served as session organizer for space plasmas, IEEE International Conference on Plasma Science 1987-1989; Guest Editor, Transactions on Plasma Science, special issues on Space Plasmas 1986, 89, 90, 92, 2000, 2003; Organizer, IEEE International Workshops on Space Plasmas, 1989, 1991, 1993, 1995, 1996, 1997, 1998, 2003; Associate Editor, Transactions on Plasma Science, 1989-; Elected member of IEEE Nuclear and Plasma Science Society (NPSS) Executive Committee (ExCom), 1987-1989; 1995- 1997; GENERAL CHAIRMAN, IEEE International Conference on Plasma Science, Santa Fe, New Mexico, 1994. IEEE NPSS ExCom Vice Chairman 1997; Elected to the IEEE NPSS Administrative Committee, 1997, named an IEEE Fellow, 1999.
He holds memberships in the American Physical Society, American Astronomical Society, Eta Kappa Nu and has earned the United States Department of Energy Distinguished Performance Award, 1987, 1999; IEEE Distinguished Lecturer Award, 1993; Norwegian Academy of Science and Letters, University of Oslo Physics Department, and Norsk Hydro Kristian Birkeland Lecturer, 1995. Dr. Peratt is Author, Physics of the Plasma Universe, Springer-Verlag (1992); Editor, Plasma Astrophysics and Cosmology, Kluwer Academic Publishers (1995); Editor, Advanced Topics in Space and Astrophysical Plasmas, Kluwer Academic Publishers (1997). Anthony Peratt can be reached at
alp@ieeetps.org
http://www.ieee.org/organizations/pubs/ ... eratt.html
Anthony L. Peratt understands the physical dynamics of space plasmas and how Double Layers form in astrophysical plasmas.
Let's take another look at Dr. Peratt's statements.
“The moving plasma, i.e., charged particles flows, are currents that produce self-magnetic fields, however weak.” — Dr. Anthony L. Peratt, Los Alamos National Laboratory, retired
“An electromotive force [mathematical equation] giving rise to electrical currents in conducting media is produced wherever a relative perpendicular motion of plasma and magnetic fields exists.” — Dr. Anthony L. Peratt, Los Alamos National Laboratory, retired
The so-called "bow shock" more accurately described as the collision point between a planet's magnetosphere and the solar wind, sets up a magnetic field which is perpendicular to the motion of the solar wind. So, when the solar wind collides with this magnetic field a Double Layer sheath boundary is formed.
A definition for Double Layer:
Plasma Dictionary wrote:Term: Double layer
Definition: A double layer is an electric charge separation region that forms in a plasma. It consists of two oppositely charged parallel layers, resulting in a voltage drop and electric field across the layer, which accelerates the plasma's electrons and positive ions in opposite directions, producing an electric current. Large potential drops and layer separation may accelerate electrons to relativistic velocities (ie close to the speed of light), and produce synchrotron radiation. Double layers may be found anywhere that plasmas are found, from discharge tubes to space plasmas to the Birkeland currents supplying the Earth's aurora. And although plasmas are highly electrically conductive, a property that tends to neutralised charges, double layers may self-generate, or form when two plasma regions with different properties come into contact. The physics of double layers are also utilised to produce ion thrusters, such as the Helicon Double Layer Thruster. More at
http://en.wikipedia.org/wiki/Double_layer. See also Nicholson, Dwight R. _Introduction to Plasma Theory_, Krieger Publishing Co., Malabar, FL, 1992.
http://plasmadictionary.llnl.gov/terms. ... age=detail
The physical properties of the Electromagnetism in plasma are scalable to at least 14 orders of magnitude.
In other words, what has been demonstrated in the laboratory can be applied to astrophysical plasmas.
Dr. Peratt's above quoted statements taken together have been fully tested and confirmed in numerous plasma laboratories.
Therefore, glyn_collinson, your answer, in brief, "However, the solar wind is basically quasi-neutral, so you won't see anything like that [Double Layers] on large scales.", is wrong.
I know you want to understand the physical dynamics of Hot Flow Anomalies, however, with due respect, you will not fully understand those dynamics, if you don't fully understand the dynamics of plasma, first. That understanding can be gained by fully understanding how plasma behaves in the laboratory -- it's dynamics are well understood both qualitatively and quantitatively from the work done in plasma laboratories -- and because plasma dynamics are scalable those understandings can be applied to astrophysical plasmas.
I would like to continue the discussion.
Given the above discussion of electromagnetism principles in plasma environments, it seems well taken to conclude colliding bodies of plasma, yes, quasi-neutral plasma, do lead to the formation of Double Layer boundary sheaths in the astrophysical environment, including the interplanetary environment, such as was studied in this paper.
With all due respect, your team's paper, in my opinion, is flawed by this basic misconception of how space plasma behaves.