Science topic

Space Plasma Physics - Science topic

Explore the latest questions and answers in Space Plasma Physics, and find Space Plasma Physics experts.
Questions related to Space Plasma Physics
  • asked a question related to Space Plasma Physics
Question
4 answers
Generally, the IV characteristics of Langmuir probes are defined for unmagnetized plasma. How to estimate the electron temperature and plasma density let's say if there is some axial field inside the plasma source(50-100G).
1. Should different kinds of probes be used for measuring in such situations? (Shielded probes).
2. Or the IV traces obtained should be corrected by using some theory?
Thanks in advance
Bharat
Relevant answer
Answer
I'm Ali from Pakistan. I hv done my master with quantum plasma and also hv One publication about low temperature plasma. Now I want to work on 2D materials in relation plasma in my PhD research. Is it possible to work and study 2D materials with respect to Plasma. Can anyone here, Please help and guide me in this respect.
  • asked a question related to Space Plasma Physics
Question
2 answers
In case of electron plasma waves we consider adiabatic compression and take gamma equal to 3 [using equation (2+N)/N]. what do we mean by adiabatic compression here?I mean physical significance.
and in case of ion waves we take gamma equal to 1. here we consider isothermal phenomena.
Please explain this in detail.
with kind regards,
purvi
Relevant answer
Answer
In addition to the very completed and interesting previous answer, Dr. Purvi Kikani I would like to add that in MHD the process to take small perturbations is considered isentropic flow meaning that the perturbation in pressure field, delta p = cs2 delta rho with cs the sound speed. That is an adiabatic reversible process to describe magnetoacoustic waves, in a homogenous plasma.
See, for instance, Landau and Lifshitz, electrodynamics of continuous media, 1984, pp. 235, Pergamon.
  • asked a question related to Space Plasma Physics
Question
7 answers
I have read somewhere that
1. if the time scales of the phenomena to be observed are larger than the times scales of plasma oscillation and
2. spatial length scales are larger than the debye length than fluid theory is applied.
I couldnt understand the second condition, means what is the significance of wavelength of launched wave greater or lower than the debye length
please explain if anybody can ...
thanks in advance
Relevant answer
Answer
I agree with most answers, Dr. Purvi Kikani, the description using fluid dynamics serves to introduce a statistical description of plasmas and goes away from the single-particle picture.
In addition the fluid dynamics serves to introduce the physical kinetics formalism into plasmas, allowing to use of the Boltzmann equation.
Best Regards.
  • asked a question related to Space Plasma Physics
Question
6 answers
when we study plasma waves (plasma oscillations, electron waves and ion waves) we study perturbation in density, velocity and electric field and use momentum, continuity and poison equation to start with.
after introducing perturbation in each quantity we do linerization of non-linear (or higher order terms).
Please explain why is it necessary at all to do it? what if we do not linearlize the quantity ?
Thank you in advance,
Purvi Dave
Relevant answer
Answer
Dear Dr. Purvi Kikani, in Landau Lifshits 8 Vol on the electrodynamics of continuous media, in the chapter on magnetohydrodynamics, the linearization of the set of MHD equations allows solving in detail the more important modes, the Alfvén mode, and the 2 magnetosonic (mw) slow and fast modes.
Otherwise there will be a set of 9 values for the general eingenvalue equation.
This linealization allows small reversible adiabatic perturbation to the equilibrium values for the density, pressure and magnetic field H.
  • asked a question related to Space Plasma Physics
Question
2 answers
When solar flare passes through earth's magnetic field its magnetic field line break and reconnect after 15 minute releasing tremendous amount of energy. Is it possible to break magnetic lines of force by some other way? And if so, doesn't it unstabilize the magnetic. And why does the earth not get unstable when its magnetic lines of force break.
Relevant answer
Answer
In 3D MR theoretical model, the MFL will not really cut-break-rejoin during the energy dissipation at the null point/line
  • asked a question related to Space Plasma Physics
Question
13 answers
What is the physical difference between the two and how are they used to study electromagnetic waves in parallel and perpendicular AC electric fields.
Relevant answer
Answer
As is known, you can use a bi-maxwellian distribution as soon as you have a temperature "anisotropy", for instance a difference between the perpandicular (Tr) and paralelle (TL) temperatures to the direction of the electromagnetic field. To use such distribution, you can simply define a transversal and longitudinal component of the velocity (Vr and VL) in order to put in the exponential term of the maxwallien distribution the sum of the square of their ratio (i.e. something like that: exp( -(VL**2/(c*TL) +Vr**2/(c*Tr))) where the product c*TL or c*Tr has the same dimension as a velocity. I hope that this short reply corresponds to what you want.
  • asked a question related to Space Plasma Physics
Question
11 answers
How we can explain the inverse relation-ship between plasma density and Debye length physically ?
Relevant answer
Answer
The explanation is not complex. Higher the density, the charge in unit volume is higher, therefore a smaller displacement produces a larger screening field.
Assuming the Debye length a measure of the equilibrium displacement, you have the answer to your question.
  • asked a question related to Space Plasma Physics
Question
6 answers
We consider small perturbation in plasma to understand the concept of plasma oscillation.
We take perturbation in velocity, density and electric field.
que-1 how do we create this perturbation (with what frequency, voltage and how ?). want to understand with physical example.
que-2 we consider small perturbation, how can we quantify this ?
que -3 what will happen if we remove the given perturbation ?
Thank you in advance,
With kind regards,
Purvi
Relevant answer
Answer
The "small" perturbations mean only the lowest-order harmonics on the plasma parameters are excited. The squares, products, or higher-order contributions from the perturbations are negligibly small. It is immaterial of the fact whether "local" or "global" equilibria are considered for the next step of homology transformations.
  • asked a question related to Space Plasma Physics
Question
24 answers
I've known that one of the unresolved problems is the Coronal heating problem and there are already many theories to explain the illogical temperature at the Corona. I need to know what are the other problems in the field of Solar Physics and what are the challenges to explain these problems?
Relevant answer
Answer
Mohamed,
Try as a potential starting point, the article makes many good points concerning the class of the problems you may encounter. To astrophysics in general I would add the coronal heating issue, the galactic halo velocity problem, the pioneer anomaly, and even the angular velocity of each sub-ring of Saturn's rings. From a chemistry point of view (rotational-vibrational energy coupling, etc), there seems to be a coupling of energy of some sort that applies to all of these issues. Like many good questions, yours could be the start of a lifelong conversation.
  • asked a question related to Space Plasma Physics
Question
6 answers
In some conditions we take average K.E. if electron in plasma as 1/2 KT and sometimes we take just 'KT'.
When should we consider what and why ?
Thank you in advance,
Purvi Dave
Relevant answer
Answer
It depends on the number of velocity dimensions you are considering in your system. For each dimension you have 1/2 KT. Therefore in 1D you should use 1/2 KT, in 2D KT and in 3D, as usual in plasma, it is 3/2 KT.
  • asked a question related to Space Plasma Physics
Question
6 answers
Why does the emission wavelength directly proportional to its duration?
Relevant answer
Answer
Solar flares and type II radio bursts have different origins and thus their durations should not be similar. It is believed that solar flares are caused by release of energy and plasma heating/acceleration due to sudden disruption of magnetic structures of parent active regions. Type II bursts are related to shock waves which can be generated in the low corona and can propagate far away in the interplanetary medium that can lasts dozens of hours. Life time of shock waves is, in general, independent of duration of an accompanying flare, even in the case when a flare is a driver of a shock wave (the case of a blast wave). In such case, a flare just generate a blast shock impulsively, and the shock is propagating freely after that. There is another case, when a shock is driven by a coronal mass ejection (the case of a piston shock). In such case, the shock wave and an associated type II burst is not dependant on an accompanying flare at all.
  • asked a question related to Space Plasma Physics
Question
4 answers
In the following technical report, Klobuchar states, " The-earliest TEC results, obtained in the late 1950s, showed the first temporal and seasonal, behavior of the topside of the ionosphere."
Klobuchar, J. A.; Aarons, J.; Mendillo, M.; Allen, R. S.; a John P. Mullen; Seeman, D. R. & Basu, S. Total Electron Content Studies of the Ionosphere IONOSPHERIC PHYSICS LABORATORY - AIR FORCE CAMBRIDGE RESEARCH LABORATORIES - L. G. HANSCOM FIELD, BEDFORD, MASSACHUSETTS, 1973
A reference was not provided and I have not been able to find a paper from the 50s that discusses the first TEC measurements. Is anyone familiar with the research being referred to?
Cheers,
Alex
Relevant answer
Answer
The first TEC measurements were made using signals bounced off the moon in the mid 1950s.  See Browne, I.C., J.V. Evans, J.K. Hargraves, and W.A.S. Murray, Radio echoes from the moon, Proc. Phys. Soc. B29, 901 (1956).  The first echoes back from the moon were reported (I think) in 1949 by DeWitt and Stodola in Proc. I.R.E., but they didn't know what was causing the systematic fading in their signal (Faraday rotation).
  • asked a question related to Space Plasma Physics
Question
9 answers
The charged particled trapped in the Van-Allen belts around Earth, maybe they affected by the natural Earth's rotational or wobbling motions and their distribution get disturbed and may reflect some radio disturbances or affect the TEC distribution in the ionosphere. 
Relevant answer
Answer
The earth's rotation is very slow compared with the the timescales of trapped radiation (microseconds for gyration, seconds for bounce between mirror points, minutes for drift around the earth) and the periods of precession and nutation are many thousands of years. What is important is the geomagnetic field which is not symmetric as the solar wind compresses it on the day side and extends it on the night side. This leads to diurnal variations as well as large, short-term variations from geomagnetic storms arising from features in the solar wind. On long timescales the earth's field is steadily changing in strength and direction and will reverse in the future. On the timescale of years we see a steady drift which alters the trapped radiation and must be allowed for in designing space systems and planning extravehicular activity on ISS. I agree that Hargreave's book is an excellent source.
  • asked a question related to Space Plasma Physics
Question
1 answer
Lets take  a 1 dimensional kappa distribution , there is any way to derive two dimensional and three dimensional kappa distribution from the given 0ne dimensional kappa distribution function. I would like to know to know whether there exists a general way which is applicable for any distribution functions
Relevant answer
Answer
I think there is no general method. It depends on the terms included in the distribution function for example if temperature anisotropy, drift, mass anisotropy etc are included in the distribution function and other distribution does not have such terms. Then one distribution function is easily solvable. But some of the distribution  functions can be derivable from others in certain limits.
  • asked a question related to Space Plasma Physics
Question
3 answers
I just read an interesting paper by Smith et al. (2012, ApJ), where they describe four characteristic regions in the power spectra of turbulent magnetic field fluctuations:
1. f < 0.5 Hz: Ion Inertial Range, Spectral Index (SI) ~ 5/3
2. f \in [0.2,3] Hz: Ion Dissipation Range, SI ~ 3, generally steeper than 1 & 3
3. f \in [3,30] Hz: Electron Inertial Range, SI ~ 2.5
4. f > 30 Hz: Electron Dissipation Range, steeper than 3
My question is: What exacly controls the extent of the ion dissipation range and how can it be distinguished from the electron inertial scale?
Looking at a lot of observations of turbulence in the solar wind, one finds that the ion inertial range seems to directly turn into the electron inertial range, without showing characteristics of a steeper ion dissipation range. E.g. in the papers by Alexandrova et al. (2009, Phys.Rev.Let.), Sahraoui et al. (2009, Phys.Rev.Let.) and Bourouaine et al. (2012, ApJ) the ion dissipation range is either very small or even non-existent.
Also there are a lot of turbulence models, that do not take the ion dissipation range into account but rather go directly from Alfven wave turbulence to kinetic Alfven wave (KAW), whistler or Hall-MHD turbulence, e.g. the weakened cascade model by Howes et al. (2011, Phys.Plas.) or the Hall-MHD model by Galtier (2006, J.Plas.Phys.).
To my knowledge there are only few papers that deal with the ion dissipation range in detail, such as Voitenko & Keyser (2011, NL Proc. in Geoph.), who call this range the weakly dispersive range and explain it with non-linear interactions of KAW that can produce very steep slopes up to SI~5.
So much for the background. Now I would like to know: What are your thoughts on this? Have you encountered problems regarding ion dissipation? Do you know how to identify ion dissipation and electron inertial ranges in your data? What do you think controls the ion dissipation range? Why is it sometimes there and sometimes not?
Relevant answer
Answer
in my recent paper I have, between others, introduced a new physical property: thermal natural frequency and explained the solar wind phenomenon
  • asked a question related to Space Plasma Physics
Question
4 answers
Would the passage of a big IDP (Interplanetary Dust Particle) passing at some distance not be an alternativeand perhaps more likely source of such soliton events?
Just like those propagating in the wake of supersonic object moving in the air?
In 1989 I suggested that electricaly charged IDP could produce characteristic electric potential variations observable by a dipole or monopole antenna that passes within the Debye sphere surrounding the interplanetary moving object. 
The passage of such an object should also generate plasma waves (why not Alfvén waves as well)  to be detectable by an ad hoc antennas system in space?
A first paper had been published in 1989 by a student of mine in PSS
LESCEUX, J.M., LEMAIRE, J. & MEYER-VERNET, N.,
ELECTRIC DIPOLE ANTENNAE USED AS MICROMETEOROID DETECTORS.
Planet. Space Sc., 37, 1291-1302, 1989.
A second one in 1996 was published JGR by a PhD student  (Peter Meuris)
MEURIS, P., MEYER-VERNET, N. & LEMAIRE, J.,
THE DETECTION OF DUST GRAINS BY A WIRE DIPOLE ANTENNA : THE RADIO DUST ANALYSER.
Journ. Geophys. Res., 101, 24471-24477, 1996.
Did you post your paper on  arXiv.org?  This is another friendly and free media to archive and easily circulate scientific papers in parallel to traditional copyright versions or reprints.
I was pleased to see that you are now active analysing ULYSSES data.
Please send me a pdf copy of your paper.
Best       Joseph
PS: Give my regards to Mark Reynolds.  I haven't heard from him for so many years...
Relevant answer
Answer
Hello again,
You are correct to produce large Alfven waves IDPs should have a diameter larger than a fraction of the wave length of the observed waves.
Of course there are solid bodies of all sizes in the interplanetary space from nano micrometeoroids to comets or fireball related objects...
The mass distribution of such objects can be found in the papers of  Ceplecha (1988) and later on... e.g. :
INFLUX OF INTERPLANETARY BODIES ONTO EARTH
CEPLECHA Z.
ASTRON.ASTROPHYS. vol: 263 p: 361..366 y:1992
Best
Joseph
  • asked a question related to Space Plasma Physics
Question
3 answers
Please ignore to give numeric explanation.
Relevant answer
Answer
For a spherical geometry, the shock wave concentrates in a ball with a small radius  around the centre point, rather than a small cylinder with a radius (half the diameter) of the same order of magnitude around the centre line. Since the volume of a ball is proportional to r^3 whereas the volume of a cylinder is proportional to r^2  the energy of the shockwave gets concentrated in a much smaller volume. That's why explosive lenses or the laser driven shockwaves in inertial confinement are very carefully set up to give shockwaves that are as spherically symmetric as possible leading to shockwave concentration in as small a ball as possible. 
  • asked a question related to Space Plasma Physics
Question
8 answers
What I mean by this question is:
There is a flare/CME eruption from an active region site (e.g., 11476). I know how to determine the possible area/volume/energy of a suace (foot-points) of a flare ribbon using the RHESSI hard X-ray data. If I use some sort of theoretical small equations and use the observational data of TEMPERATURE, EMISSION MEASURE of GOES/RHESSI/YOHKOH, it may give any possibility, but I am not sure if it can be reasonable. I am looking for any code or technique that will help me to determine the possible amount of energy erupted from the active region of the Sun.
Relevant answer
Answer
Make use of Spectral observational data in different wave-band (including Visible light, Infred light, ultraviolet, X-ray, gama-ray ect.), with the spectral diagnosis method and the spectral profile analysis, it is possible to measure these physical parameters mentioned above. It is a possible way.
  • asked a question related to Space Plasma Physics
Question
7 answers
As some of the research papers suggest that low FIP (below 10 KeV) elements get enhance by factor of 3-4 in Corona from Photosphere, while high FIP (above 10 KeV) elements don't show this characteristics.
Does this effect conclude anything about energy transfer from Photospere to Corona ?
Relevant answer
Answer
The question is most easily addressed using a multi fluid picture, in
which different atoms, electrons and ions separately reach local
equilibrium so that each is described by a number density, center of
mass momentum, and temperature. This works because particles of
similar mass tend to "relax" via collisions faster than those of
different masses. Conservation equations for mass, momentum and energy
< SORRY RESEARCHGATE DROPPED 90% OF MY ANSWER... grrr... >
are given by the SUM of separate equations for each species, and
coupling between different species is described by differences between
these equations (e.g. Schunck 1977). This coupling can be thought of
as "friction" between different atoms, ions, electrons. The question
of energy transport into the corona is then seen as identifying terms
essentially in the energy equation for each species, or for the total
plasma (predominantly hydrogen, protons and electrons in the Sun). We
are yet to successfully identify the precise mechanisms in the energy
equation(s) that describe coronal heating, but it appears related to
magnetic fields threading the plasma (based a wealth of data since the
1960s demonstrated this). Most models focus only on the total energy
equation. The trick with coronal heating is to transport ordered
energy into the corona and dissipate it ("friction" being a useful
concept to destroy ordered motion- such ordered motion might be bulk
flows or differences in flows between protons and electrons,
electrical currents, for example) under conditions that have very weak
dissipation (low friction) unless tiny scales can be generated.
The question of abundance differences concerns DIFFERENCES in the
multi-fluid equations. The fact that the FIP (with high FIP being >
10 eV not keV) appears important indicates that the action dictating
the abundance differences occurs in plasma where high FIP elements are
neutral, low FIP ionized. These conditions exist in the photosphere,
chromosphere (..spicules, prominences). The "friction" scales with
density. A large amount of friction (such as in the photosphere)
means that all species will tend to be strongly coupled- a single
fluid picture thus applying and abundances not changing. Thus the
photosphere is probably ruled out. Thus we look to the chromosphere to
separate elements according to FIP. Martin Laming has a model in
which the forces trying to separate different species are Alfven
waves. Myself and Hardi Peter have a review in 2000 discussing more
generally the problem of separation of species in the chromosphere.
So to answer your question, while both the coronal heating problem and
abundance issues are easily related through the multi-fluid formalism
that seems appropriate, and both depend on friction at some level or
other (friction being used both for destruction of ordered motion in
the total energy equation or in destruction of ordered motion between
different particle species), the two phenomena are of slightly
different origins and so are not necessarily coupled in a decisive
way. Only by introducing a specific model describing processes in the
governing equations can one tell if these two phenomena are really
closely coupled, or a "red herring" (false trail).
I hope this helps
Philip Judge
  • asked a question related to Space Plasma Physics
Question
3 answers
And if possible the methodology of extracting such datasets.
Relevant answer
Answer
Thank you for the address. I have started working it out.
  • asked a question related to Space Plasma Physics
Question
3 answers
Takayuki Umeda et al. [Computer Physics Communications, 2001] suggested that an absorbing boundary can be used to absorb the outgoing electromagnetic waves. How can we deal with the particles at such boundary? Could you make some comments on it?
Relevant answer
Answer
Is the particle the source of  E and B field?
  • asked a question related to Space Plasma Physics
Question
3 answers
Ground-based vertical plasma drift is inferred from the time rate of change of hmF2 or h'F (the virtual height of the F-layer)
Relevant answer
Answer
paper about chemical corrections for the vertical plasma drift calculation is for example:
Bitencourt, J. A., Abdu, M. A., A theoretical comparison between apparent and real vertical ionization drift velocities in the equatorial F-region. Journal of Geophysical Research 86: 2451-2454, 1981.
  • asked a question related to Space Plasma Physics
Question
8 answers
In one paper I got that said after using the equilibrium condition the secular term will vanish. What is the form of this secular term?
Relevant answer
Answer
Note that "secular" means the term that has some singularity. That is, if you have some function depending on x and this function behave around x0 as 1/(x-x0), you says that your function is secular. In the paper that you have given the phrase about disappear of secular term means that some expression, permitting formally the dividing by zero in its content at some value of its variable, in reality is finite there. For instance, this is a case at x=0 for sin(x)/x. What is about the paper under discussion, it seems that the authors have qualified as equilibrium conditions their relations (38) and (39): It is these relations that appeared as conditions for their field function \phi had not taken value \infty at some point.
As a matter of fact, I am not experienced in derivation of equations of the type of KdV. More better understanding of the situation might have appearred had you repeated the derivation of their equation in accordance with recipes that the authors propagandise (In the parer and in the other papers of theirs). The other way - to find out anybody of them and to ask him to help with respective difficulties.
  • asked a question related to Space Plasma Physics
Question
4 answers
What is coronal loop? Where from it originates? What is its contribution to coronal heating? How to model it and which model is appropriate for theoretical investigation?
Relevant answer
Answer
For historical completeness, we should include the Craig, McClymont and Underwood 1978, A&A , 70, 1. This gives essentially the same solutions as the better remembered RTV paper. The motivation for considering these solutions was driven by SkyLab observations that suggested considering active region structures as isolated atmospheres would be a reasonable approximation.
On a personal note, I would caution young scientists not to be seduced by the beauty of these approximations. The underlying assumption is that the magnetic field is so strong in the corona, that it can be ignored and we can spend great effort on the 1-D hydrodynamics and forward modeling the optically thin radiation. This was brilliant, 30 years ago, but one time would be better spent confronting more realistic 3-D, MHD (or multi-fluid) radiation hydrodynamics. The set of equations is nasty, but range of physical behavior is compelling and worthy of detailed study.