Talk:Double layer (plasma physics)

Untitled
There is something seriously wrong with the momentum formula in the Mathematical description part of this article. The units of $$m_e v_e$$ do not match the units of $$eE$$ - which again do not match the units of $$\partial v_e/\partial x$$.

My instincts tell me that the ">" should not be there. So, it's a 1-dimensional version of $$m (\mathbf v \cdot\nabla) \mathbf v = -e \mathbf E$$. However, I'm not an expert in the field, I'd prefer someone verify. I'm being bold and making the change, but if someone knows better, feel free to revert. 132.165.76.2 (talk) 10:37, 10 December 2010 (UTC)


 * No, no. You are quite right. Thank you. --Art Carlson (talk) 10:56, 11 December 2010 (UTC)

Reference [10] in the introduction no longer links to the .pdf file listed. I believe the file is located here: https://digitalcollections.anu.edu.au/bitstream/1885/45749/5/02whole.pdf But I'm not too savvy on how that particular link falls in with licensing and all that, so I'll hold off making the edit myself. — Preceding unsigned comment added by 98.245.116.144 (talk) 18:58, 2 November 2013 (UTC)

What is a "wavemode"?
This article uses the term. It appears nowhere else on Wikipedia. Equinox (talk) 20:45, 6 July 2015 (UTC)

'Health Warning' for Readers of this Double Layer Article
The claim made in this article that double layers are particle accelerators is incorrect.

A double layer is a surface covered with dipoles, each having its axis in the direction of the normal to the surface. The potential at any external point is equal to the product of the dipole moment per unit area of the double layer and the solid angle subtended at that point. Consequently, the potential difference between any two points at large distances from the double layer tends to zero, so a charged particle’s kinetic energy after traversing a double layer is conserved, along with its total energy.

The article, in contrast, makes the mistake of applying an analysis performed in one dimension to the real world, to deduce that there is a net potential difference, and that a double layer is able to accelerate charged particles. In particular:

The figure presented in ‘Double layer formation’ correctly indicates no change of potential, but is discussed as though there were a change, and that electrons having created a double layer could accelerate themselves away from it! The figure presented under ‘Features and characteristics of double layers’ violates Poisson's Equation by ignoring the external electric field.

The article as it stands is, therefore, self-contradictory and at variance with the basic physics of central-force fields. It requires major revision or removal from Wikipedia.

RAL2014 (talk) 13:06, 23 January 2016 (UTC)

Proposed Amendment
As a first step in making revisions to the article as suggested above the following is proposed:

•	Edit the introductory paragraphs which should define the attributes of a double layer.

•	Remove the mathematical section which is based on too many assumptions and is therefore unhelpful in its flawed treatment. Working with a single dimension and selecting only parts of the structure serves no purpose in describing, explaining, or promoting any understanding of double layers. RAL2014 (talk) 12:52, 30 January 2016 (UTC)

Amended article completed
Changes have been made to the article with the aim of making this double layer article more balanced, and to remove some misleading and inconsistent parts with a minimum of editing to retain the existing structure. These recent amendments have been made in stages, but should be treated collectively to make sense. It is felt that the article could still benefit from further objective scientific editing, to provide a broad but more concise overview of this plasma phenomenon. Importantly, a distinction has to be made between actual observations, theory, and speculation. A few key citations are still outstanding.

RAL2014 (talk) 15:23, 17 February 2016 (UTC)

Impartiality of edits
I am very concerned that the edits by RAL2014 may violate Wikipedia policies on impartiality, neutral point of view, balanced descriptions of disputed issues (especially views held by a minority of the published work on a subject). When the subject of electron acceleration came up on concerning the aurora article (an exchange between myself and RAL2014 on the talk page), I almost immediately received an email from Duncan Bryant and Martin Courtier, Bryant being a vocal opponent the idea of acceleration by double layers.

From the context, I think it is very possible that RAL2014 is in contact with Bryant, is not impartial or neutral, and may have an undisclosed conflict of interest on the subject. (Also note that Bryant is retired from Rutherford–Appleton Laboratory, commonly referred to as RAL.)

As far as this article is concerned, I do not think RAL2014's edits reflect a neutral point of view. The idea of whether or not double layers can accelerate particles is not a subject of universally agreement. When such a consensus is lacking, Wikipedia articles are supposed to present a balanced description of both sides of the debate. This is especially important when one one view is held by a small minority of the people in a field. That is clearly the case here.

For example, a review in Nucl. Fusion (39, 1071, 1999), of a book by Duncan Bryant begins, "Duncan Bryant is a retired space plasma physicist who spent most of his career at the Rutherford–Appleton Laboratory in Oxfordshire, England. For many years he has been challenging a widely accepted theory, that auroral electrons are accelerated by double layers, on the grounds that it contains a fundamental error (allegedly, an implicit assumption that charged particles can gain energy from conservative fields)." This quote shows that there is a "widely accepted theory" on the subject. RAL2014 has been editing articles to make it sound as if this idea is clearly unphysical and untrue.

Fcrary (talk) 20:38, 1 February 2018 (UTC)

‘It is noted that these unhelpful and personalised comments from Fcrary are inconsistent with those which the author posted under ‘Talk’ within the Wikipedia ‘Aurora’ Article, which he refers to above.

Specifically, that post said ‘Talk pages are not a place for editors to argue their personal point of view about a controversial issue’. Furthermore, he proposed to discontinue wikipedia correspondence, and to pursue clarity through a direct exchange of emails. This has not happened.

No reply has been received to an email sent directly to him on 1 April 2016. This questioned some assertions regarding ‘double layers’ and views on auroral electron acceleration given in his earlier Aurora ‘Talk’ comments, dated 4 March 2016.

In presenting the above personalised, unethical and unscientific comments these points are also ignored. The administrators of the Article are invited to remove such provocative text under ‘Talk’, and to also remind the author to resolve his problems directly with colleagues.’

RAL2018 (talk) 14:04, 30 June 2018 (UTC)

Well, no.

(1) My above comments were not debating a personal view on the subject; it was expressing my concern about another editor's possible, personal conflict of interest. That's not about the subject of aurora, but about the tone and neutrality of the article or an editor.

(2) I did not initiate or suggest any direct email; that started with an email sent directly to me by Duncan Bryant and Martin Courtier. From the context, it was clear that one or both were the editor using the name RAL2014. Since Duncan Bryant has strong opinions on the subject of this article, that's a serious problem for impartiality. (And, for reference, I stopped replying after Bryant and Courtier repeatedly refused to answer specific, technical questions on the subject.)

(3) Now I'm seeing comments from a RAL2018. That's enough like the previous editor, RAL2014, to make me wonder if it's the same person or persons. If so, that's also a cause for concern. If not, how do you know about the date of emails between Bryant/Courtier and myself?

(4) Expressing a concern about impartiality is not "unethical and unscientific." In fact, it's the opposite. As far as I know, this article does not have any administrators, and in any case, deleting other editors' comments on a talk page is a serious policy issue.

Fcrary (talk) 19:34, 30 June 2018 (UTC)

Impression given by the above, which are statements more suitable for a gossip magazine

1)	The comments are defamatory towards individuals.

2)	This comment misrepresents the facts, and has no place here. Replies to all questions from Frank Crary have been provided by email.

3)	This comment is devoid of any substance.

4)	This is another vacuous comment, and best removed to avoid inciting edit wars on Wikipedia.

RAL2018 (talk) 09:45, 26 July 2018 (UTC)

This (edit of August 8, 2018) is the second time RAL2018 has deleted another users comments from this discussion page. I believe this is both against Wikipedia policy and grossly unethical. Please stop it. Fcrary (talk) 19:29, 8 August 2018 (UTC)