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plasma physics +rep
Guys just doing some reading around the subject!!
Plasma physics is so weird!!
"Plasma is a form of matter where the atoms are broken into pieces. The pieces are called electrons and ions. Because these pieces have an electric charge, they are pulled together or pushed apart by electric fields and magnetic fields. This makes a plasma act different from a gas, which is another form of matter. For example, magnetic fields can be used to hold a plasma, but not to hold a gas."
Taken from simple english wiki^^
So they are some sort of werid gas/liquid sort of thing? (very technical i know
)
any simple explanation and roles of plasma in "real" life help please!
THanks guys
+rep aswell.
Plasma physics is so weird!!
"Plasma is a form of matter where the atoms are broken into pieces. The pieces are called electrons and ions. Because these pieces have an electric charge, they are pulled together or pushed apart by electric fields and magnetic fields. This makes a plasma act different from a gas, which is another form of matter. For example, magnetic fields can be used to hold a plasma, but not to hold a gas."
Taken from simple english wiki^^
So they are some sort of werid gas/liquid sort of thing? (very technical i know
) any simple explanation and roles of plasma in "real" life help please!THanks guys
+rep aswell.
Well plasmas are considered a fourth state of matter and the early universe was a plasma (a sea of electrons and protons). If the temperature of the plasma is kept high enough then the electrons and protons will not pair up into atoms (just like at the start of the universe, atoms only started to form at recombination, i.e. the time at which the temperature of the universe fell enough to not be able to support the plasma state). This was also the point at which the universe became transparent as the mean free path of a photon in a plasma is quite small since a plasma is made up of charged particles, of which photons interact with and scatter off. So when the charged particles formed neutral atoms, the mean free path of the photons becomes approximately infinite.
One of the uses of plasmas that I can think of is in a tokomak reactor, although I can't quite remember the in's and out's of what the purpose is. What I do remember is that the tokomak uses magnetic fields to confine the plasma.
Hope this sheds some light on plasmas.
One of the uses of plasmas that I can think of is in a tokomak reactor, although I can't quite remember the in's and out's of what the purpose is. What I do remember is that the tokomak uses magnetic fields to confine the plasma.
Hope this sheds some light on plasmas.
0 div curl F
Well plasmas are considered a fourth state of matter and the early universe was a plasma (a sea of electrons and protons). If the temperature of the plasma is kept high enough then the electrons and protons will not pair up into atoms (just like at the start of the universe, atoms only started to form at recombination, i.e. the time at which the temperature of the universe fell enough to not be able to support the plasma state). This was also the point at which the universe became transparent as the mean free path of a photon in a plasma is quite small since a plasma is made up of charged particles, of which photons interact with and scatter off. So when the charged particles formed neutral atoms, the mean free path of the photons becomes approximately infinite.
One of the uses of plasmas that I can think of is in a tokomak reactor, although I can't quite remember the in's and out's of what the purpose is. What I do remember is that the tokomak uses magnetic fields to confine the plasma.
Hope this sheds some light on plasmas.
One of the uses of plasmas that I can think of is in a tokomak reactor, although I can't quite remember the in's and out's of what the purpose is. What I do remember is that the tokomak uses magnetic fields to confine the plasma.
Hope this sheds some light on plasmas.
super cool!!
um bit stuck on the italic bit!
Well, I found a definition in my super-easy-to-read guide to the mysteries of the universe:
"In the plasma-state, the matter is so hot that the electrons have escaped the atoms they are usually confined to, creating a mess of nuclei (ions, I guess) and electrons. Thus these two particles are moving freely between each other" - it was written in Danish, so pardon me if anything was lost in translation Seen very often in stars, apparently.
"In the plasma-state, the matter is so hot that the electrons have escaped the atoms they are usually confined to, creating a mess of nuclei (ions, I guess) and electrons. Thus these two particles are moving freely between each other" - it was written in Danish, so pardon me if anything was lost in translation
Seen very often in stars, apparently.0 div curl F
Well plasmas are considered a fourth state of matter and the early universe was a plasma (a sea of electrons and protons). If the temperature of the plasma is kept high enough then the electrons and protons will not pair up into atoms (just like at the start of the universe, atoms only started to form at recombination, i.e. the time at which the temperature of the universe fell enough to not be able to support the plasma state). This was also the point at which the universe became transparent as the mean free path of a photon in a plasma is quite small since a plasma is made up of charged particles, of which photons interact with and scatter off. So when the charged particles formed neutral atoms, the mean free path of the photons becomes approximately infinite.
One of the uses of plasmas that I can think of is in a tokomak reactor, although I can't quite remember the in's and out's of what the purpose is. What I do remember is that the tokomak uses magnetic fields to confine the plasma.
Hope this sheds some light on plasmas.
One of the uses of plasmas that I can think of is in a tokomak reactor, although I can't quite remember the in's and out's of what the purpose is. What I do remember is that the tokomak uses magnetic fields to confine the plasma.
Hope this sheds some light on plasmas.
Tokamaks are meant to generate plasma...
one use is in fusion reactors, it needs to be as hot for the reaction to occur
kam_007
super cool!!
um bit stuck on the italic bit!
um bit stuck on the italic bit!
Well a photon is the force carrier (gauge boson) of the electromagnetic field and it interacts with charged particles (or other photons) so if there were many charged particles in the early universe (which there were) then the photons (i.e. the radiation in the early universe) have a lot of interactions with the particles so the distance they travel between interactions is very small (much like a photon travelling inside the sun, I think they take approx - 1 million years to escape from the sun because they are being scattered continually by the charged particles that make up the sun). But at recombination, the charged particles recombine to form neutral atoms, of which the chances of photon interacting with a neutral atom are much, much smaller than with a sea of charged particles so the mean free path of the photon (i.e. the distance it travels between interactions) is very large.
Does this make any more sense?
Nice clear explanation - though of teaching dvf?
0 div curl F
Well a photon is the force carrier (gauge boson) of the electromagnetic field and it interacts with charged particles (or other photons) so if there were many charged particles in the early universe (which there were) then the photons (i.e. the radiation in the early universe) have a lot of interactions with the particles so the distance they travel between interactions is very small (much like a photon travelling inside the sun, I think they take approx - 1 million years to escape from the sun because they are being scattered continually by the charged particles that make up the sun). But at recombination, the charged particles recombine to form neutral atoms, of which the chances of photon interacting with a neutral atom are much, much smaller than with a sea of charged particles so the mean free path of the photon (i.e. the distance it travels between interactions) is very large.
Does this make any more sense?
Does this make any more sense?
i think i get it:
Plasma is a state where atoms are split into electrons and ions (charged particles). a kind of 4th state of matter. (as you said)
Early universe was all plasma. but when the universe colled down: recombination, the charged particles formed atons again, which did not interact with the remaining charged particles, so began to spread out and form the universe??
Also if stars are mainly plasma, and they release energy by nuclear fussion! so how does this work?? thanks guys.
Simple version: Light nuclei collide; under the condiotions at the centre of the Sun, they form larger nuclei which releases energy.
Hydrogen gets turned into Helium
Hydrogen gets turned into Helium
I visited JET last week 
Real Life Use:
JET stands for Joint European Torus, it is one of the most "famous" research projects in the fusion area. Their purpose of research is to harness the energy gained from fusing isotopes of hydrogen together which results in energy being released.
JET uses a Tokamak vessel (doughnut shaped) to heat a low pressure gas so that it changes into a plasma, as previously mentioned a sea of positive and negative charges. This plasma is needed so that the isotopes of hydrogen are able to overcome the repulsive forces between the nuclei and fuse together to form helium. For fusion to occur, temperatures of 100 million deg C are required. The plasma allows temperatures like this to be reached, however it needs to be contained otherwise it would melt the walls of the vessel.
Because the plasma is made up of positive nuclei and negative electrons, several strong magnetic fields are applied to the plasma to hold it in place around the Tokamak vessel. The charges "surf" the waves of the field. Being able to contain and maintain the heat allows scientists to get the isotopes of hydrogen to fuse.
In the sun, magnetic fields aren't required because the gravitational pull keeps the plasma in place.
Real Life Use:
JET stands for Joint European Torus, it is one of the most "famous" research projects in the fusion area. Their purpose of research is to harness the energy gained from fusing isotopes of hydrogen together which results in energy being released.
JET uses a Tokamak vessel (doughnut shaped) to heat a low pressure gas so that it changes into a plasma, as previously mentioned a sea of positive and negative charges. This plasma is needed so that the isotopes of hydrogen are able to overcome the repulsive forces between the nuclei and fuse together to form helium. For fusion to occur, temperatures of 100 million deg C are required. The plasma allows temperatures like this to be reached, however it needs to be contained otherwise it would melt the walls of the vessel.
Because the plasma is made up of positive nuclei and negative electrons, several strong magnetic fields are applied to the plasma to hold it in place around the Tokamak vessel. The charges "surf" the waves of the field. Being able to contain and maintain the heat allows scientists to get the isotopes of hydrogen to fuse.
In the sun, magnetic fields aren't required because the gravitational pull keeps the plasma in place.
You can use them to clean things and deposit things on stuff too.
http://en.wikipedia.org/wiki/Plasma_cleaning
http://en.wikipedia.org/wiki/PECVD
These are the two ways I've encountered plasmas as a scientist.
http://en.wikipedia.org/wiki/Plasma_cleaning
http://en.wikipedia.org/wiki/PECVD
These are the two ways I've encountered plasmas as a scientist.
Olibert
I visited JET last week
.
.
Nice.
I'm hoping to organise a visit for my students next year.
Olibert
I visited JET last week
Real Life Use:
JET stands for Joint European Torus, it is one of the most "famous" research projects in the fusion area. Their purpose of research is to harness the energy gained from fusing isotopes of hydrogen together which results in energy being released.
JET uses a Tokamak vessel (doughnut shaped) to heat a low pressure gas so that it changes into a plasma, as previously mentioned a sea of positive and negative charges. This plasma is needed so that the isotopes of hydrogen are able to overcome the repulsive forces between the nuclei and fuse together to form helium. For fusion to occur, temperatures of 100 million deg C are required. The plasma allows temperatures like this to be reached, however it needs to be contained otherwise it would melt the walls of the vessel.
Because the plasma is made up of positive nuclei and negative electrons, several strong magnetic fields are applied to the plasma to hold it in place around the Tokamak vessel. The charges "surf" the waves of the field. Being able to contain and maintain the heat allows scientists to get the isotopes of hydrogen to fuse.
In the sun, magnetic fields aren't required because the gravitational pull keeps the plasma in place.
Real Life Use:
JET stands for Joint European Torus, it is one of the most "famous" research projects in the fusion area. Their purpose of research is to harness the energy gained from fusing isotopes of hydrogen together which results in energy being released.
JET uses a Tokamak vessel (doughnut shaped) to heat a low pressure gas so that it changes into a plasma, as previously mentioned a sea of positive and negative charges. This plasma is needed so that the isotopes of hydrogen are able to overcome the repulsive forces between the nuclei and fuse together to form helium. For fusion to occur, temperatures of 100 million deg C are required. The plasma allows temperatures like this to be reached, however it needs to be contained otherwise it would melt the walls of the vessel.
Because the plasma is made up of positive nuclei and negative electrons, several strong magnetic fields are applied to the plasma to hold it in place around the Tokamak vessel. The charges "surf" the waves of the field. Being able to contain and maintain the heat allows scientists to get the isotopes of hydrogen to fuse.
In the sun, magnetic fields aren't required because the gravitational pull keeps the plasma in place.
Yeah i was reading about this last week!! They can't get the hydrogen atoms close enough for long enough for them to fuse? And the energy required to run the magnets + keep the plasma etc... doesn't make it viable at the minute right?
kam_007
Yeah i was reading about this last week!! They can't get the hydrogen atoms close enough for long enough for them to fuse? And the energy required to run the magnets + keep the plasma etc... doesn't make it viable at the minute right?
Oh, they have got them to fuse. And also, the JET project never set out to make fusion power viable. The purpose of JET was to research the techniques needed, conditions etc before using those in the much larger ITER project. ITER is in France and is currently working on making a reactor that could make fusion energy viable to generate electricity. (ITER means "The Way" in Latin)
To start up the toroidal magnetic fields and get the plasma heated to 100 million deg C requires a current of 5 million amps top pass through the gas. Hence why they can't keep it going for too long. (The period of time that fusion actually occurs is about 20 seconds)
ITER will then lead to DEMO, the demonstration power plant capable of generating 2000MW of power with net electricity production.
And the reason I know this is because I'm writing a report for physics at the moment about fusion
, so I have been surfing the interwebs a lot to find informtion.Olibert
ITER will then lead to DEMO, the demonstration power plant capable of generating 2000MW of power with net electricity production.
ITER will then lead to DEMO, the demonstration power plant capable of generating 2000MW of power with net electricity production.
What's the net power output that they are predicting for DEMO?
ITER is still what they are concentrating on after JET. The "net power" from DEMO is very much a prediction.
http://www.iter.org/a/index_nav_2.htm
That text explains that ITER is still one step from building the demonstration plant.
http://www.iter.org/a/index_nav_2.htm
That text explains that ITER is still one step from building the demonstration plant.
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