Birkeland's Scientific Publications Discussed

tusenfem

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tusenfem
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As there is always a lot of discussion about Birkeland in the PU/EU/ES/EC threads, I did a lot of discussion of Birkeland's work, published in his book or in journals. I think this discussion deserves its own thread.

I will copy some of the posts I made in the "iron sun" etc. threads, where I discussed B's work into this thread.
 
Birkeland’s paper in Archive des Sciences Physiques et Naturelles 1916 (here is the link to the pfd or any other format, just to save you from searching if you need it). There are two papers, one from page 22 to 37 and one from page 109 to124, written in 1915 during Birkelands stay in Egypt. Both are called: Les rayons corpusculaires du soleil qui penètre dan l’atmosphere terrestre sont-ils négatifs ou positives? and belong together.

It is quaint reading for a modern scientist, as a lot of extra text is inserted that nowadays would not get through the referee process anymore, maybe a loss? But anyway, before I digress, let’s go to the first claim that Birkeland (henceforth B) makes on page 23, regarding M. Prof. Störmer:



So, this deals (like the title says) with the particles that penetrate the Earth’s atmosphere and produces the aurora. Apparently, see quote, Störmer claimes that positive charges are creating the aurora. B is not in agreement with that, he thinks that the charges are negative (and as we now know, he is right, but that as an aside), and points to his Norwegian Expedition book, page 609.

Then some discussion about his terrella, and about positive and negative auroras, where the positive ones apparently are produced in the afternoon, whereas the aurora borealis and the negavit polar storms happen in the night with a maximum near midnight. (see for an explanation his book pages 580-571, don’t know why the numbers are reversed and pages 536-540). He discusses that the measurements he made are in agreement with negative charge leading to aurora

Then on page 24 he makes the following claim about positive charges:



So, if the positive charges would penetrate than it would be in a region where the magnetic field is calm and this leads to his conclusion that the positive charges do not enter the atmosphere. But the positive charges that probably exist in space, do not get close enough to the Earth to be measured, we will have to go there to prove their existence. And B himself has never been able to observe these positive rays.
Before he will show that Störmer is wrong he takes a sidestep to the zodiacal light in §2page 25. Naturally this goes back to his idea that the zodiacal light is also some sort of discharge (which we now know it wrong, it is just reflected light off dust, to keep it simple). He then claims that, page 25:



So the zodiacal light is produced by both positive and negative rays in his view. I will not go into the whole description of the zodiacal light, you can read it for yourself in the link. However, I will give one more quote here about the zodiacal light, which is “reproduced” in the terrella with the terrella itself as a cathode. From page 27



So, he could imagine that a similar disk as in his terrella chamber (Fig. 2) could exist around the sun giving rise to the zodiacal light. Indeed, on page 18 B writes:



(taches solaires = sun spots) So, he claims that there can be a immense disk of “rays” (of corpuscules) rotating around the sun. The cathode rays (electrons) can hit ions in this disk, liberating more electrons. These can all interact with the sunlight, and if I interpret this text correctly, he steps down from the discharge model for the zodiacal light, but says it is probably scattered sun light.

Then the discussion turns to Saturn’s rings, which I will skip and on page 29 in §3 the causes de grand changements climateriques de la periode tertiaire are discussed, which I will skip too, because this was going to be an the positive and negative charges emitted by the cathode Sun, and not whether variations in the solar emission can have an effect on the climate (though interesting that B also was thinking about that).
Then a discussion about the aurora again, the particles arrive and leave the atmosphere at an estimated height of 500 km. And I think B is also describing the westward surge of a substorm on page 32.

Now B keeps on talking about the rayons cathodiques solaires, and in the time of his experiments these cathode rays were electrons and up to page 34 I have no doubt that B means electrons when he uses this term. On page 34 he refers again to this book page 591-595, where experiments are done with cathode rays of various energy (1800 and 2400 V) and shows how the energy of the cathode rays makes the location of the auroral rings on his terrella change location. He estimates the product of the magnetic field H and the larmor radius ρ and he came to the conclusion that, page 35:



Then some discussion about Störmer again and then at the end of part 1, page 37:



So, he needs highly energetic cathode rays, which he calls helio-cathode rays, and he calculated that the “negative electrical tension” to emit those rays would have to be 600 million Volts. B concludes the first part then with, page 37:



After this, is seems that we have to admit that the sun, in various circumstances, during electric eruptions often of very short duration, may send out rays that hit the Earth and for which Hp is between one and hundred million.

End of the first part of the paper. There is no mention on why B thinks that positive and negative charges are send out from the sun, but that is not surprising, as that is not what the paper is about. This is mainly to show that Strömer is wrong by assuming that the aurora is created by positive rays.

Okay, that was part one. Part two will come later.
 
Having gone through the second part of Birkeland's paper, I must conclude that there is nothing specific about the sun that is discussed in there. It is mainly showing that Störmer is wrong in his assumption that the aurora is created by positively charged corpuscules, and some more discussion about climate effects from variations of the Sun, etc. So, I guess I have to go back to Birkeland's books on the auroral expidition and look at the pages he cited above.

However, I did ponder on what Birkeland wrote and specifically his term "rayons helio-cathodiques" or translated "helio-cathode rays." I think that the main quote from his paper in this case is:



... that I had the idea that we would have to make very strong cathode rays, that I have called helio-cathode rays; I have calculated that the negative electric tension necessary for the emission of these rays is about 600 million volts.

So, the sun emits very strong cathode rays, which is early 20th century speak for electrons. However, the energy of these cathode rays should be so immense 600 million volts, that I guess Birkeland could not envision how such an energy would be possible in the laboratory or on Earth, so he decided to call them "helio-cathode rays," just a very energetic subset of cathode rays.

Hehehehehe I just found this link to Christiania videnskabs-selskab where there is an english translation of the french paper, go figure!

So, where does this bring us?

I think the following. Birkeland experimented with his terrellas, and also wanted to make a link to things he observed on the sun. Now, from what he wrote in the now-discussed paper, he does think that there are positive and negative corpuscules emitted by the Sun. However, I do think that Birkeland did not mean that the Sun is a cathode (though maybe in his book he may state otherwise I need to check that) because "cathode" is always accompanied by "ray" and as an experimental scientist working with electricity all the time, I am sure Birkeland also understood that cathodes do not emit positive corpuscules. I am, therefore, also not sure whether the New York Times reporter has written it up wrongly or that Birkeland was indeed mistaken about the depositing of platinum on objects connected to the anode.

Next step, back to pages 580-571 and 536-540 of the book and see what we learn there.

For the rest, MM can jump in anytime to give his interpretation of what I have just discussed here.
 
Let's go to Birkies book (coz I need to use it anyway for my presentation on Aurora in September). This terella pic first shows up in Book 3, Chapter IV, page 84 (or page 765 (661) of the pdf). Mr. B. writes (my bolding):



So, it apparently serves many purposes, first it is supposed to be Saturn's rings and then suddenly come a "ring around the sun" creating zodiacal light. Anyway, in this whole study note that the matter is radiant, i.e. it produces its own light, which is clearly not what the rings of Saturn and zodiacal light are doing.

Then there is some discussion about coronium (interesting that MM has not taken that up).

Then Mr. B. starts to discuss discharges, and finds "white spots" on his globe.



Then an interesting comment:



Though interesting this may be, we know that sun spots are magnetic structures. So, it is reminiscent of, but that is all. The experiment is NOT a model for the emission of a sunspot as the globe was unmagnetized. Although later the globe gets "slightly magnetized" and then there are still pencils of cathode rays.

Then about "MM's mountains"



Then the pressure of the gas is increased in the experiment.



and then something about vortices in these "stars"



Then on page 769(665) the same picture turns up as at the beginning of the chapter, the one describing the rings of Saturn. About the picture Mr. B. now writes:



(ofcourse Mr. B was wrong about field lines here, they do not exist as the magnetic field is a conituum, but that as an aside)

Now, here it is getting interestig, because how is this cathode "discharging" onto itself? I do not see an explanation for this, in the text, how this discharge is happening in the terella, where the globe is only a cathode. I guess we would have to find the answer at the bottom of the page:



What I think is happening is that there is, indeed, a discharge between the cathode ball and the anode box. With the strong magnitization of the ball, the electrons will follow the magnetic lines of force, and they excite the "dense" gas, making it glow and at the "tips" of the luminiscent rings, the electrons are uncoupled and go to the anode, which is not visible in the pictures that Birkeland took.

So, unfortunately, this experiment, how interesting it may be, does not describe sun spots, nor solar flares.
 
I hope you can get the quotes back tusenfem.

This thread could become a valuable resource.
 
Okay, this is going to be a repeat of the previous, but now with the Birkeland and other quotes in the text.

First posts on french paper (which is also available, slightly different, in English, links to both versions are in the text)

Birkeland’s paper in Archive des Sciences Physiques et Naturelles 1916 (here is the link to the pfd or any other format, just to save you from searching if you need it). There are two papers, one from page 22 to 37 and one from page 109 to124, written in 1915 during Birkelands stay in Egypt. Both are called: Les rayons corpusculaires du soleil qui penètre dan l’atmosphere terrestre sont-ils négatifs ou positives? and belong together.

It is quaint reading for a modern scientist, as a lot of extra text is inserted that nowadays would not get through the referee process anymore, maybe a loss? But anyway, before I digress, let’s go to the first claim that Birkeland (henceforth B) makes on page 23, regarding M. Prof. Störmer:

B said:
M. Stôrmer termine sa publication en se demandant si les rayons de l'aurore boréale sont produits par des corpuscules positifs ou négatifs et il croit pouvoir prouver qu'il s'agit de particules électriques chargées positivement.
Je pense que le raisonnement qui conduit le prof. Stôrmer à cette conclusion est certainement inexact à cause de la manière dont il traite les orages magnétiques polaires.
Click to expand...

So, this deals (like the title says) with the particles that penetrate the Earth’s atmosphere and produces the aurora. Apparently, see quote, Störmer claimes that positive charges are creating the aurora. B is not in agreement with that, he thinks that the charges are negative (and as we now know, he is right, but that as an aside), and points to his Norwegian Expedition book, page 609.

Then some discussion about his terrella, and about positive and negative auroras, where the positive ones apparently are produced in the afternoon, whereas the aurora borealis and the negavit polar storms happen in the night with a maximum near midnight. (see for an explanation his book pages 580-571, don’t know why the numbers are reversed and pages 536-540). He discusses that the measurements he made are in agreement with negative charge leading to aurora

Then on page 24 he makes the following claim about positive charges:

B said:
Il semble après cela que si des rayons positifs pénètrent dans l'atmosphère terrestre c'est à peine s'ils peuvent donner lieu à un effet magnétique perceptible, parce que leur action devrait précisément être un maximum pendant la période que nous avons reconnu être absolument calme.
Mais dans les espaces cosmiques, les rayons polaires positives qui existent probablement et même certainement ne semblent pas s'approcher assez de la terre pour qu'on puisse affirmer leur présence dans notre atmosphère. Il serait d'un grand intérêt d'effectuer des observations au levant de la terre sur ce phénomène, et de prouver par là l'existence de rayons solaires positifs; en ce qui me concerne je n'ai jamais rien pu observer de ce genre.
Click to expand...

So, if the positive charges would penetrate than it would be in a region where the magnetic field is calm and this leads to his conclusion that the positive charges do not enter the atmosphere. But the positive charges that probably exist in space, do not get close enough to the Earth to be measured, we will have to go there to prove their existence. And B himself has never been able to observe these positive rays.

Before he will show that Störmer is wrong he takes a sidestep to the zodiacal light in §2page 25. Naturally this goes back to his idea that the zodiacal light is also some sort of discharge (which we now know it wrong, it is just reflected light off dust, to keep it simple). He then claims that, page 25:

B said:
Au point de vue physique, il est très probable que ces nouveaux rayons solaires ne sont exclusivement ni des rayons positifs ni des rayons négatifs, mais sont des rayons des deux sortes.
Click to expand...

So the zodiacal light is produced by both positive and negative rays in his view. I will not go into the whole description of the zodiacal light, you can read it for yourself in the link. However, I will give one more quote here about the zodiacal light, which is “reproduced” in the terrella with the terrella itself as a cathode. From page 27

B said:
Nous avons vu comment autour de la sphère magnétique qui sert de cathode, il se forme un faisceau de rayons dans le plan de l'équateur magnétique. Je suppose qu'un faisceau pareil, mais de dimensions considérables, se trouve autour du soleil et tourne avec lui à cause de la manière dont il a été formé.
Click to expand...

So, he could imagine that a similar disk as in his terrella chamber (Fig. 2) could exist around the sun giving rise to the zodiacal light. Indeed, on page 18 B writes:

B said:
L'on observe cette période régulièrement, qu'il y ait des taches solaires ou non; elle est bien marquée aussi bien pour un minimum que pour un maximum des taches solaires. Ce fait considéré avec ma théorie des orages polaires magnétiques appuie l'idée que l'immense disque de rayons autour du soleil tourne toujours avec lui. Daus mon ouvrage A. P., p. 623, j'ai mentionné quelques faits connus au sujet du pouvoir de la matière radiante d'absorber et de diffuser la lumière solaire. Il est concevable que les rayons hélio-cathodiques lors de leur collision avec des ions dans l'espace cosmique produisent un grand nombre d'électrons de dispersion qui peuvent être entraînés et se trouver en raisonnance avec les ondes lumineuses provenant du soleil. Il est probable que c'est de cette manière que le disque de rayons corpusculaires autour du soleil nous est visible comme une lumière zodiacale.
Click to expand...

(taches solaires = sun spots) So, he claims that there can be a immense disk of “rays” (of corpuscules) rotating around the sun. The cathode rays (electrons) can hit ions in this disk, liberating more electrons. These can all interact with the sunlight, and if I interpret this text correctly, he steps down from the discharge model for the zodiacal light, but says it is probably scattered sun light.

Then the discussion turns to Saturn’s rings, which I will skip and on page 29 in §3 the causes de grand changements climateriques de la periode tertiaire are discussed, which I will skip too, because this was going to be an the positive and negative charges emitted by the cathode Sun, and not whether variations in the solar emission can have an effect on the climate (though interesting that B also was thinking about that).

Then a discussion about the aurora again, the particles arrive and leave the atmosphere at an estimated height of 500 km. And I think B is also describing the westward surge of a substorm on page 32.

Now B keeps on talking about the rayons cathodiques solaires, and in the time of his experiments these cathode rays were electrons and up to page 34 I have no doubt that B means electrons when he uses this term. On page 34 he refers again to this book page 591-595, where experiments are done with cathode rays of various energy (1800 and 2400 V) and shows how the energy of the cathode rays makes the location of the auroral rings on his terrella change location. He estimates the product of the magnetic field H and the larmor radius ρ and he came to the conclusion that, page 35:

B said:
De ces expériences j'ai tiré la conclusion que pour les rayons corpusculaires solaires qui pénètrent dans la zone aurorale on a :
H ρ = 3 X 106 (A. P., 595 ).
Mais j'ai admis que la valeur de Ho n'est pas toujours la meme et peut varier de 1 à 10 millions.
Click to expand...

Then some discussion about Störmer again and then at the end of part 1, page 37:

B said:
Ce n'est que plus tard, lorsque j'eus trouvé que Hp valait 3 millions pour les rayons projetés dans la zoneaurorale, que j'eus l'idée que nous avions à faire à des rayons cathodiques très puissants que j'ai appelés les rayons hélio-cathodiques; j'ai calculé que la tension électrique négative nécessaire à la projection de ces rayons était de 600 millions de volts.
Click to expand...

So, he needs highly energetic cathode rays, which he calls helio-cathode rays, and he calculated that the “negative electrical tension” to emit those rays would have to be 600 million Volts. B concludes the first part then with, page 37:

B said:
D'après cela, il semble que nous pouvons admettre que le soleil, en diverses circonstances, lors d'éruptions électriques fréquemment de très courte durée, peut envoyer des rayons qui atteignent la terre et pour lesquels Hp est compris entre un et cent millions.
Click to expand...

After this, is seems that we have to admit that the sun, in various circumstances, during electric eruptions often of very short duration, may send out rays that hit the Earth and for which Hp is between one and hundred million.

End of the first part of the paper. There is no mention on why B thinks that positive and negative charges are send out from the sun, but that is not surprising, as that is not what the paper is about. This is mainly to show that Strömer is wrong by assuming that the aurora is created by positive rays.
Okay, that was part one. Part two will come later.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Having gone through the second part of Birkeland's paper, I must conclude that there is nothing specific about the sun that is discussed in there. It is mainly showing that Störmer is wrong in his assumption that the aurora is created by positively charged corpuscules, and some more discussion about climate effects from variations of the Sun, etc. So, I guess I have to go back to Birkeland's books on the auroral expidition and look at the pages he cited above.

However, I did ponder on what Birkeland wrote and specifically his term "rayons helio-cathodiques" or translated "helio-cathode rays." I think that the main quote from his paper in this case is:

Birkeland said:
... que j'eus l'idée que nous avions à faire à des rayons cathodiques très puissants que j'ai appelés les rayons hélio-cathodiques; j'ai calculé que la tension électrique négative nécessaire à la projection de ces rayons était de 600 millions de volts.
Click to expand...

... that I had the idea that we would have to make very strong cathode rays, that I have called helio-cathode rays; I have calculated that the negative electric tension necessary for the emission of these rays is about 600 million volts.

So, the sun emits very strong cathode rays, which is early 20th century speak for electrons. However, the energy of these cathode rays should be so immense 600 million volts, that I guess Birkeland could not envision how such an energy would be possible in the laboratory or on Earth, so he decided to call them "helio-cathode rays," just a very energetic subset of cathode rays.
Hehehehehe I just found this link to Christiania videnskabs-selskab where there is an english translation of the french paper, go figure!

So, where does this bring us?

I think the following. Birkeland experimented with his terrellas, and also wanted to make a link to things he observed on the sun. Now, from what he wrote in the now-discussed paper, he does think that there are positive and negative corpuscules emitted by the Sun. However, I do think that Birkeland did not mean that the Sun is a cathode (though maybe in his book he may state otherwise I need to check that) because "cathode" is always accompanied by "ray" and as an experimental scientist working with electricity all the time, I am sure Birkeland also understood that cathodes do not emit positive corpuscules. I am, therefore, also not sure whether the New York Times reporter has written it up wrongly or that Birkeland was indeed mistaken about the depositing of platinum on objects connected to the anode.

Next step, back to pages 580-571 and 536-540 of the book and see what we learn there.

For the rest, MM can jump in anytime to give his interpretation of what I have just discussed here.
 
Let's go to Birkies book (coz I need to use it anyway for my presentation on Aurora in September). This terella pic first shows up in Book 3, Chapter IV, page 84 (or page 765 (661) of the pdf). Mr. B. writes (my bolding):
Birkeland said:
We have already several times had occasion to give various particulars regarding the manner in which these experiments were carried out. It is by powerful magnetisation of the magnetisable globe that the phenomenon answering to Saturn's rings is produced. During this process, polar radiation and disruptive discharges at the equator such as that shown in fig. 247b [that would be the terrella pic, 1005] (which happens to be a unipolar discharge) may also occur, if the current intensity of discharge is great. If the magnetisation of the globe be reduced (or the tension of the discharge increased) gradually, the luminous ring round the globe will be reduced to a minimum size, after which another equatorial ring is developed and expands rapidly (Fig. 247 b) [which would be a side view of a ring around the terrella, 1005]. It has been possible for the ring to develope in such a manner that it could easily be demonstrated by radiation on the most distant wall of my large vacuum-tube (see fig. 217). The corresponding ring would then have a diameter of 70 cm., while the diameter of the globe was 8 cm.

It is a corresponding primary ring of radiant matter about the sun that in my opinion can give an efficient explanation of the various zodiacal light-phenomena.
Click to expand...

So, it apparently serves many purposes, first it is supposed to be Saturn's rings and then suddenly come a "ring around the sun" creating zodiacal light. Anyway, in this whole study note that the matter is radiant, i.e. it produces its own light, which is clearly not what the rings of Saturn and zodiacal light are doing.

Then there is some discussion about coronium (interesting that MM has not taken that up).

Then Mr. B. starts to discuss discharges, and finds "white spots" on his globe.
Birkeland said:
In the experiments represented in figs. 248 a e, there are some small patches on the globe, which are due to a kind of discharge that, under ordinary circumstances, is disruptive, and which radiates from points on the cathode. If the globe has a smooth surface and is not magnetized the disruptive discharges come rapidly one after another, and are distributed more or less uniformly all over the globe (see a). On the other hand, if the globe is magnetised, even very slightly, the patches from which the disruptive discharges issue, arrange themselves then in two zones parallel with the magnetic equator of the globe; and the more powerfully the globe is magnetised, the nearer do they come to the equator (see b, c, d|. With a constant magnetisation, the zones of patches will be found near the equator if the discharge-tension is low, but far from the equator if the tension is high.
Click to expand...

Then an interesting comment:
Birkeland said:
If the pressure of the gas is very small during these discharges, there issues (fig. 249, globe not magnetised) from each of the patches narrow pencil of cathode-rays so intense that the gas is illuminated all along the pencil up to the wall of the tube. This splendid phenomenon recalls our hypothesis according to which sun-spots sometimes send out into space long pencils of cathode-rays.
Click to expand...

Though interesting this may be, we know that sun spots are magnetic structures. So, it is reminiscent of, but that is all. The experiment is NOT a model for the emission of a sunspot as the globe was unmagnetized. Although later the globe gets "slightly magnetized" and then there are still pencils of cathode rays.

Then about "MM's mountains"
Birkeland said:
If the metallic globe surrounding the electro-magnet is not smooth, but has sharp points on its surface, for instance near the poles, the disruptive discharges would issue at these points, and it will be necessary to use a stronger magnetisation to make the patches arrange themselves in zones round the equator.
Click to expand...

Then the pressure of the gas is increased in the experiment.
Birkeland said:
If the pressure of the gas increases, the pencils of rays no longer issue radially from the globe, as in fig. 249, but the disruptive discharges as seen to manifest themselves in the shape of a star with four or five arms (see fig. 250), coming from an eruptive spot, and almost following the surface of the non-magnetic globe, to meet often at a point on the globe diametrically opposite.
Click to expand...
and then something about vortices in these "stars"
Birkeland said:
It almost always happens too, in the experiment in which the cathode-globe is magnetised, that there are two or three luminous branches turning in a spiral about the eruptive spot and near the surface of the globe. These vortices move in the opposite direction to that of the hands of a watch on the hemisphere containing the magnetic north pole, and in the same direction on the opposite hemisphere.

This corresponds exactly with the results recently obtained by HALE, ELLERMAN, and Fox relative to vortices in the hydrogen filaments and calcium vapour round a sun-spot, provided it is admitted, as I have found, that the sun and the earth are inversely magnetised
Click to expand...

Then on page 769(665) the same picture turns up as at the beginning of the chapter, the one describing the rings of Saturn. About the picture Mr. B. now writes:

Birkeland said:
Fig. 253 shows how a branch of discharge issuing from the spots sometimes follows the magnetic lines of force in the neighbourhood of the equator, giving rise to a phenomenon which greatly resembles the black filaments on the sun, studied by HALE, ELLERMAN, Fox, EVERSHED, DESLANDRES and D'AZAMBUJA.
Click to expand...
(ofcourse Mr. B was wrong about field lines here, they do not exist as the magnetic field is a conituum, but that as an aside)

Now, here it is getting interesting, because how is this cathode "discharging" onto itself? I do not see an explanation for this, in the text, how this discharge is happening in the terella, where the globe is only a cathode. I guess we would have to find the answer at the bottom of the page:
Birkeland said:
Sun-spots may be considered as the eruptive centres of similar disruptive discharges, and the question then immediately arises: Where shall we seek for the positive pole of these discharges, in which the spots, or that which surrounds them, represent the cathode?

There are several possible solutions to this question.

In the first place, it might be imagined that the interior of the sun formed the positive pole for enormous electric currents, while perhaps the faculae, in particular, round the spots, formed the negative poles. Or it might be imagined that the positive poles for the discharges were to be found outside the photosphere, for instance in the sun's corona, the primary cause of the discharge being the driving away of negative ions from the outermost layers of the sun's atmosphere in some way or other for instance, as ARRHENIUS has assumed, by light-pressure after condensation of matter round them. Finally, it might be assumed and this, according to the experimental analogies, seems the most probable assumption - that the sun, in relation to space, has an enormous negative electric tension of about 600 million volts.
What I think is happening is that there is, indeed, a discharge between the cathode ball and the anode box. With the strong magnitization of the ball, the electrons will follow the magnetic lines of force, and they excite the "dense" gas, making it glow and at the "tips" of the luminiscent rings, the electrons are uncoupled and go to the anode, which is not visible in the pictures that Birkeland took.
Click to expand...

So, unfortunately, this experiment, how interesting it may be, does not describe sun spots, nor solar flares.
 
MM said:
All his physical experiments were based on a metallic sphere, so there is a an "element" of assumption that one tends to come to. In other words he does tend to imply it's probably a metallic iron sphere, but like any good scientist, he left all options on the table. He was far more interested in promoting the electrical aspects (cathode aspects) of his solar theory, not necessarily trying to limit the concept to a solid surface solar model.
I do not think that Birkeland ever made the assumption that the Sun was a metallic sphere, unless you can show some proof of this, it can be swept into the wastebucket of MM solar model ideas.
Click to expand...

The only reason why Birkeland used a metal sphere is because he wanted to understand how electric currents create e.g. the aurora and to mimic the processes seen on the Sun, at comets or at Saturn. To quote from the paper just linked to by MM:
Rypdal & Brundtland said:
(Page C4-117)
In two gas discharge set-ups, he produced results which he interpreted as current whirls around a metallic sphere painted with phosphorescent material, with an electromagnet inside. The spheres in each case simulated the Earth with its magnetic field. The currents were created by a cold cathode discharge between electrodes in the tube, and were seen on the terrella as illuminations of the phosphorescent paint and as wedges of light
with embedded rays in the rarefied gas. He could see two narrow rings of light around the poles of the sphere which was interpreted as aurora in miniature.

(Page C4118)
Ten different terrellas are described with diameters from 2.5 to 36 cm. In the first experiments, performed in the autumn of 1900, Birkeland used two terrellas, 5.0 and 7.5 cm in diameter. The electromagnets with core and windings were shaped as spheres and surrounded with a thin crust of brass covered with a coat of barium platinocyanide. Birkeland was well aware that he could not achieve quantitative similarity to natural magnetic conditions.
...
All the other terrella experiments of Birkeland were described in the treatise from the third arctic expedition [2], which covers his lab work from 1901-1913. Many of the experiments were performed with terrellas where the coil and thus the magnetic axis were tilted relative to the vertical axis.
During the experiments he was able to rotate the terrellas around the vertical axis, and in this way he studied the effect of the eccentricity of the Earth's magnetic poles on the aurora.
When first starting systematic terrella experiments he used cylindrical tubes, with a volume of approximately 12 liters, as shown in Fig. 3. Experiments in this tube were also used for comparison with the orbit calculations of Carl St~irmer. For direct comparison with experiments wire models were made for visualization of the trajectories in space, as shown in Fig. 4.
Click to expand...
Then there is a little confusion there, because Birkeland switched from having separate anode, which role was later taken over by the terrella.
Rypdal & Brundtland said:
(Page C4-118)
When simulating the aurora in the laboratory Birkeland had to give the terrella some sort of atmosphere. This problem was solved in various ways. In the early weak discharges the surface of the terrella was covered with a phosphorescent paint that produced visible light when hit by the rays.
Later he described another method that made it easier to observe rays in the surrounding space. By running a high current through the magnetizing coil, the terrella surface became hot and gave off gas. He then reduced the magnetic field to the desired value, ignited the discharge, and took pictures. A third method was to cover the surface with a thin layer of pump oil, which evaporated during the dicharge.
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Note that the terrella is still an anode as the electrons need to go there to produce the aurora in the "liberated" gas.

Then to investigate the zodiacal light, which he also presumed to be a discharge (however it is reflected light off dust) he

Rypdal & Brundtland said:
(Page C4-119)
This experimental set-up was very similar to the one for the aurora, but the polarity of the discharge was changed. The terrella, which was without phosphorescent coating, was now negative and served as the cathode, simulating the Sun. He used one or two aluminium discs for anodes.
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Then he starts to look at solar phenomena, with the same cathode terrella.
Rypdal & Brundtland said:
(Page C4-121)
During earlier experiments he had seen that disruptive discharges could radiate from points on the cathodic terrella surface. With a low gas pressure, a vefy high discharge current and with no magnetic field around the terrella, he could create arcs from points on the surface to the anode disc and chamber walls.
...
These point discharges, which were spread all around the surface of the terrella, were interpreted by Birkeland as small sunspot models. He observed that the spots were easier to make when the surface was rough. When introducing magnetic field on the terrella, he observed that the spots were
grouped in two zones at a certain northern and southern magnetic latitude. By increasing the field the zones moved closer to the equator of the sphere. At increasing magnetic field the sunspots turned into luminous bands which coalesced at the equator.
After running discharges, he took out the terrella and studied it in a microscope, and observed small craters where the spot discharges had been. This observation supported his hypothesis that mass is thrown out from the Sun during solar flares. Some of this atomic dust, falls back to the surface of the Sun, some disappears into Space, and some will end up orbiting the Sun, and slowly clump together and form planets. He considered the asteroid belt as masses halfway in the process from solar dust to planets.
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So, in the end, Birkeland saw what was happening on the metal sphere and then interpreted it, not by saying that the Sun is a metal sphere, but that Sun spots are discharge endings where atomic dust is flung away from the Sun. This atomic dust then forms the planets. I think we can safely assume that Birkeland knew that the planets are not made out of iron (actually his terrella sphere was made of brass, because ....) and therefore would never have concluded that there is an iron sphere in the Sun.

He may have been paranoid at the end of his life, but he was not stupid.
 
MM said:
Again, this is simply a false statement. Birkeland even did a whole series of calculations for you after page 664 or so that were directly related to the movements of both positively and negatively charged particles from the sphere, but I doubt any of you bothered to read any of it. None of you bothers much to educate yourselves on what's actually been done in a lab before you claim it's "impossible".
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Okay, I took the pdf again, and looked through many pages, starting at 664. The math starts later, but that is about (see page 697-698 of the book, that is 802 of the pdf page counting)
birkeland said:
135. We have discussed above the problem of the mouvement of an electrically charged particle about a magnetic and gravitating sphere, when the particle is ejected in the plane of the magnetic equator, and thus always remains there. We saw that there were boundary-circles towards which the particles, under certain conditions, could draw nearer and nearer, this giving rise to the formation of planets. It still remains for us to investigate the conditions outside the plane of the equator whether the formation of planets is also possible there, when the particles are flung out anywhere on the sphere or not.
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This is all really nice what he does, and then basically goes on on this topic in the next pages, calculating all kinds of boundaries and circles that particles in that system of a magnetized and gravitating sphere can or cannot reach. Up to now I have seen no mention of any electric field being used. And basically, these calculations have to do with the creation of planets as our old friend writes on page 706:
birkeland said:
(end of section 135)
Hence we may conclude, that formation of planets will hardly be possible outside the equatorial plane. If after all a multitude of trajectories could approach asymptotically a common curve outside the equatorial plane, this curve as we have shown could not lie in a plane passing through the centre of the sphere, and as further the particles certainly very soon will lose their charge, they will come to move in the most different directions. The only possibility for formation of planets must be, that the particles approached a common curve lying in a plane through the centre of the magnetic sphere, and this we have proved to be impossible.
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Yes, the particles are charged, but no there is no electric field, only gravity and the magnetic field of the sphere. However in section 1.36 he claims the following:
birkeland said:
Our mathematical investigations have shown as their result that if boundary-circles exist for all the velocities with which material corpuscles are expelled from the central body, the corpuscles will either return to the central body (this being what will happen in the great majority of cases), or the particles will continue to approach nearer and nearer to the boundary-circles. Possibly some velocities may also be sufficiently great to cause the particles in question to leave the system and retire indefinitely.

Concerning the charge of the particles, we may imagine three cases:
I. When the particles are not charged. They will then either retire indefinitely, or fall down again.
II. When the particles are so highly charged that the electrostatic influence dominates that of gravitation.
III. When the particles carry a charge of medium strength, so that the electrostatic influence plays an important part side by side with gravitation, which, however, is the dominating force.

If we consider negative particles in case II, we shall easily be able to prove that they can in approach boundary-circles, but the radius of these circles must be < (1 + sqrt(2))r0 .
However, in the equations that Birkeland used up to this point there were (unless I have not looked well enough) only the magnetic field and the gravitational field in the equations of motion of the particles. So, I don't know exactly how to rhyme this, without going detailed through the derivation, for which I do not have time right now. However, the rest of the mathematical analysis is based on getting the particles to certain limiting circles and thus creating the planets and until now I have not found anything that describes the solar wind, or electrons being accelerated by an electric field from the sun to the heliopshere (or whatever Birkeland may have called it as that term probably did not exist in his time) and the electrons dragging along the ions.
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I am gladly set straight if I have made an error in my skipping through the Birkeland book. Maybe I missed how the solar wind is created.
 
Okay, I think I have moved everything now in the correct way and actually posts 2-3-4 could be deleted from this thread.

Looking forward to some intelligent discussion on what Birkeland really wrote.
 
Bumping this thread, in the unfounded hope that MM will really discuss B's science.
 
tusenfem said:
Okay, I think I have moved everything now in the correct way and actually posts 2-3-4 could be deleted from this thread.

Looking forward to some intelligent discussion on what Birkeland really wrote.
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Interesting stuff! Wow! You've done lot of good work here. Thank you.
 
tusenfem said:
I think the following. Birkeland experimented with his terrellas, and also wanted to make a link to things he observed on the sun. Now, from what he wrote in the now-discussed paper, he does think that there are positive and negative corpuscules emitted by the Sun. However, I do think that Birkeland did not mean that the Sun is a cathode (though maybe in his book he may state otherwise I need to check that) because "cathode" is always accompanied by "ray" and as an experimental scientist working with electricity all the time, I am sure Birkeland also understood that cathodes do not emit positive corpuscules.
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Define the term "sputtering" for me.
 
Michael Mozina said:
Define the term "sputtering" for me.
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Wow, so many posts and you ask about something that is not even in the thread! Well done Mikey!

Sputtering, in the regular (space)physics definition, is that high energy particle (either ionized or not) impact on a solid surface (although it is sometimes expanded to include atmospheres) and they kick out particles from the surface.

As an example: The moon Europa in the Jovian magnetosphere. The magnetosphere rotates faster than the moon orbits Jupiter. This means that the magnetoplasma overtakes the moon and where Europa is in the way the magnetoplasma impacts the surface of the moon and thereby kicks out particles, that get ionized and get picked up by the Jovian magnetic field.

Here is a paper of mine that (amongst others) deals with this topic.
 
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