Keep in mind that Parker's original paper essentially suggested that whatever the heat source of the corona might be, he "assumed" it would tend to emit both types of charged particles from the corona purely from the standpoint of kinetic energy. In section 4 of his famous 1958 paper, Parker simply "assumes" that the continuous heat source of the corona could not be EM field related which seems unlikely even in mainstream models frankly:Brigit Bara wrote:As I understand it, there are fast electrons from the sun which are emitted and accelerated by even small flares. This is consistent with the theory that the flares are exploding double layers, which supply the power to separate charges and fling them out into space. For the general reader (:
Parker doesn't really treat electron motions independently from ion motions in his paper but rather he 'assumes" that kinetic energy is transported from the photosphere to the corona and then that kinetic energy is absorbed by the corona which results in solar wind of both types of particles. Essentially he's moving the kinetic energy problem (or source) into the photosphere where it has to be transported to and absorbed by the corona so the kinetic energy in the corona can turn into solar wind in the corona. The implication is that the mechanical kinetic energy transfer process effects *both* electrons and ions, although his reference (Fermi) is discussing ions.But let us suppose that the corona cannot be heated electromagnetically, and so, presumably, must be heated by mechanical means (van de Hulst 1953). We shall suppose that by some mechanical process, such as acoustical or hydromagnetic waves, energy is transported from the photosphere out through the corona(4) and is finally absorbed in thermal motions beyond r=a to heat the coronal gas.
(4)In the following paper we suggest that it is probably hydromagnetic waves that are responsible for heating by Fermi acceleration of ions (Fermi 1949, 1953)
Parker then suggested in section 4 that hydromagnetic waves were somehow providing spherical and homogeneous heating to the corona via hydromagnetic waves which would in fact be EM field related anyway.
Effectively his heating problem for the corona is only marginally defined, but he doesn't really offer a way to explain why it would be heated uniformly and spherically all around the sun at the same continuous rate. Essentially he handwaves in the hydromagnetic heat (kinetic energy) wave argument without really "explaining" it all that well. Presumably this is a "nanaflare' type of continuous emission from the photosphere from all around the sun's photosphere into the corona.
It's my understanding that the PSP equipment can measure particle flow from all directions.But what this interesting conversation about the namesake of the Parker Probe inspired me to wonder, and what I would like to know is, whether a tenuous electron drift toward the sun can be detected.
In other words, can anything among the payload of scientific instruments detect the drift of electrons in the opposite direction of the solar wind?
The difference between the anode and cathode configuration would primarily be related to electron flow inside the corona. According to Juergens, electrons should flow into the corona, while the ions should flow out of the corona double layer. According to Birkeland, the electrons flow outbound from the cathode (below the surface of the photosphere) and provide the kinetic energy to the ions which should also flow out of corona as well, perhaps based on thermal processes as Parker assumes, if only by kinetic energy transfer alone. There should also be a higher speed (and outbound) "strahl" component involved in Birkeland's model since not all the electron kinetic energy will be absorbed by the coronal ions and some high speed electrons should pass right on through the corona without colliding with ions. "Eventually" (beyond the corona?), ions should also be flowing into the sun too, presumably as high speed "cosmic rays". Slower speed (solar wind speed) ions should move away from the sun in Birkeland's model, while the faster cosmic ray ions should flow toward the sun.Follow up: If the instruments are set up to detect charged particles, but only in one direction, is it possible that the results will be of limited value in answering any question about either an anode or a cathode sun?
As far as I know, the particle movement patterns detected by previous satellite missions all tend be congruent with Birkeland's particle flow predictions based on a cathode surface heat (kinetic energy) source. To my knowledge the overall electron movement is *away* from the sun, not toward the sun as we would expect in Juergen's anode model. The magnetic field lines around the sun would probably result in flow movements in all directions in the corona, particularly in and around coronal loops which are surface to surface discharges.
The forbidden topic is "electric field" in astronomy. As I understand it, the PSP has the capacity to measure electric fields as well as particle flow patterns in all diretions. It's a bit like sticking a Langmuir probe into the corona. In Parker's model/explanation, there really shouldn't be an electric field present in the corona in the first place since it's primarily a thermal (kinetic energy) transfer process that is *not* EM field related according to Parker. In both the anode and cathode solar models, there should be a measurable electric field present in the corona. The only difference between EU/PC models is the orientation of that field. Just the ability to measure the electric fields inside the corona should allow us to differentiate between a purely thermal process (Parker), vs an anode (Juergens) or cathode (Birkeland) heating process. I think NASA is likely to choke on the concept of publicly describing the electric field data that they measure from the probe. The can describe the particle flow patterns without mentioning electric fields so that part isn't likely to be a sticking point for NASA. On the other hand, describing the electric field data is going to present a serious problem for them IMO.My experience is that it is extremely difficult for anyone at NASA to even pronounce the words "electrons" and "sunward" in the same paragraph, let alone sentence. This kind of language is studiously avoided, so in your opinion MMozina (or any one), do you think it will be possible for the instruments to perform any measurements on the movement of electrons sunward?
If Juergen's anode model is right, you're correct, they'll be very unhappy about describing any inbound electron flow that they might detect. If Birkeland's cathode model is right, the solar wind and strahl (high speed electron) particle flow movements would almost exclusively be moving particles *away from* the sun in the corona, and only high speed cosmic ray ions would be moving inbound toward the sun. In both EU solar models however there should be a measurable electric field present in the corona, whereas Parker's model specifically ignores that possibility, and no electric field should exist in the corona in Parker's model.Any charges at all moving toward the sun may be kind of a headache for them -- unless they can come up with an excuse why that does not mean the sun is an electrode. Maybe that would be the best we might be able to expect for the money (: ?? (:
Theoretically speaking, the absence or the presence of a measurable electric field inside the corona should differentiate between Parker's purely thermal model and either electric field driven EU/PC model of coronal heating, and the orientation of that electric field (assuming one exists) should differentiate between the two different EU models. Whether or not they can accurately measure all the various particles from all different directions, the electric field orientations (or lack thereof) inside the corona should be enough information to falsify or verify various models. The model described by Parker is mostly an exclusively mechanical and thermal transfer process whereas Birkeland and Juergen's predict the presence of a measurable electric field inside the corona.
The key here is to see what NASA has to say about the electric field data from the probe, or whether they avoid discussing that topic altogether. They'll most likely wait until they've gotten closer to the sun than they did on their first pass before they start to discuss that electric field data IMO, especially if they measure a strong electric field on the first pass. They'll want to confirm it's existence in several close passes before they discuss it IMO. Keep in mind that this pass was considerably further away from the photosphere than future passes. In theory, the electric field data should show an increase in field strength as they move closer and closer with each pass.