I What is the new source of space radiation discovered near Earth?

[geoelectronics]

As I inferred implied moments ago, I've studied electron beam deflection in a cyclotron. Your video doesn't make me understand anything more perfectly, as it's basically the same thing.

In the above post, the OP said:
"As I inferred implied moments ago, I've studied electron beam deflection in a cyclotron. Your video doesn't make me understand anything more perfectly, as it's basically the same thing. "

Dear OP.
If you've studied cyclotron theory, you know that electrons (let's call them charged particles in this discussion), are deflected into an almost circular path by a stationary perpendicular magnetic field. For a given magnetic field the circular path will hold them in different "orbits" depending on their kinetic energy (speed):

If nothing is done to alter their kinetic energy, they keep going around in those orbits forever. You've heard of CRT displays, magnetic bottles magnetic lenses and e-e+ storage rings?
Charged particles change their speed (energy state) up and down by external interactions, which are many. If free space, perfect vacuum, they find little reason to change states (Newton's First Law):
In a cyclotron, energy is added by alternating the electrical charge on the Dees, accelerating the charged particles into a widening spiral- by the time they have reached the exit port, their energy is of the magnitude required for the experiment or industrial project:

Charged particles, magnet = Solar Wind, earth.
Here the layers are formed one again by the magnetic field, separated by their speed, into different orbits.

Perhaps better than a cyclotron, the action of a mass spectrometer is a more appropriate example because here we have a charged particle (ion) at a predetermined speed, interaction with a fixed magnet of appropriate flux, but in this case, assuming the charged particles are the same speed, they are separated my their mass.

Speaking directly to the electrons and charged particles in orbit around the earth, they occupy orbital altitude base on their speed.

If their speed changes, they will occupy a higher or lower orbit (“layer”) accordingly.

Check out the “First Cosmic Velocity”

Thank goodness for our strong magnetic field, without it, the world would be very different.

Geo

 

[berkeman]

If nothing is done to alter their kinetic energy, they keep going around in those orbits forever.

Is that true? It's true for a straight path, but for a curved path, something happens to steal energy from the charged particle, no?

 

[OmCheeto]

Is that true? It's true for a straight path, but for a curved path, something happens to steal energy from the charged particle, no?

Cyclotron radiation?
As I said, I've studied up on cyclotrons. It doesn't mean I fully understand how they work.
I'm guessing they leave out a lot of minor details.
For instance, why don't the particles seem to be affected by gravity? Are cyclotrons designed to minimize the effect? Likewise, a lack of knowledge of cyclotron radiation might lead someone to claim that the particles inside a cyclotron would stay in orbit forever.

Viewpoint: Cyclotron Radiation from One Electron
...
Electric charges radiate when moving in circular orbits in a magnetic field, an effect that was first predicted by Oliver Heaviside in 1904. Cyclotron radiation has been observed in astrophysical radio sources and is the basis for generating x rays at synchrotrons.
...

Btw, I'm getting a sense of how these "space accelerators" work. But some of the details are unfortunately left up to my imagination, which is quite dangerous.

Perhaps I should go back and review the wiki entry;

Van Allen Radiation Belt: Causes​

It is generally understood that the inner and outer Van Allen belts result from different processes. ​

Never mind. This is what we pay scientists for isn't it? To get rid of the "generally"? Sounds like mansplaining.

 

[berkeman]

Btw, I'm getting a sense of how these "space accelerators" work. But some of the details are unfortunately left up to my imagination, which is quite dangerous.

 

[Vanadium 50]

If you've studied cyclotron theory, you know that electrons (let's call them charged particles in this discussion), are deflected into an almost circular path by a stationary perpendicular magnetic field. For a given magnetic field the circular path will hold them in different "orbits" depending on their kinetic energy (speed):

If nothing is done to alter their kinetic energy, they keep going around in those orbits forever.

Except that it doesn't. Cyclotrons have only weak focusing. A circular orbit has no restoring force perpendicular to the plane, so you need to either a) continually accelerate and extract before the beam hits the floor or the ceiling, or b) put the beam on a potato-chip shaped orbit so that there is some focusing in the perpendicular direction.

You picked a bad example.

 

[geoelectronics]

Is that true? It's true for a straight path, but for a curved path, something happens to steal energy from the charged particle, no?

I hope I'm using "quote" correctly, if not please give guidance...

Are you asking if the curved path intrinsically reduces energy vs. a straight path?

Otherwise, yes even photons can alter an electron's energy state markedly, it doesn't have to be another particle of matter.

Geo

 

[berkeman]

Are you asking if the curved path intrinsically reduces energy vs. a straight path?

Yep! Through what mechanism? (and yes, this is a test...)

 

[geoelectronics]

Yep! Through what mechanism? (and yes, this is a test...)

Induction.
a.k.a. electromagnetic induction.

Geo

 

[geoelectronics]

Yep! Through what mechanism? (and yes, this is a test...)

Is the static magnetic field at right angles to the motion of the electron, or some other angle?
Right angle presents a circular e- path, other angles present a spiral, as shown in the video.

Geo

 

[mfb]

Induction.
a.k.a. electromagnetic induction.

Geo

No.
Synchrotron radiation (aka cyclotron radiation, same concept). This has been mentioned before already. Charged particles flying through a magnetic field not aligned with their flight direction emit some of their energy as radiation.

For instance, why don't the particles seem to be affected by gravity? Are cyclotrons designed to minimize the effect?

Gravity is negligible compared to all the other forces the particles experience. If you want to store particles for a relevant time span you need focusing magnets (or, rarely, electric fields) anyway.

 

[geoelectronics]

No.
Synchrotron radiation (aka cyclotron radiation, same concept). This has been mentioned before already. Charged particles flying through a magnetic field not aligned with their flight direction emit some of their energy as radiation.
Gravity is negligible compared to all the other forces the particles experience. If you want to store particles for a relevant time span you need focusing magnets (or, rarely, electric fields) anyway.

You didn't specify relativistic speeds. We were talking about Solar Wind (~ 1 million miles per hour). Not near the speed of light. Is this forum only for quantum physics, or is classical everyday physics allowed?
Perhaps I misunderstood. Geo

 

[mfb]

You didn't specify relativistic speeds.

The whole thread is about electrons at relativistic speeds. Not that it would matter, at lower speeds it is called cyclotron radiation but it is fundamentally the same concept: Charges being deflected by a magnetic field radiate.

We were talking about Solar Wind (~ 1 million miles per hour).

The protons are slow but this thread is about the electrons.

Is this forum only for quantum physics, or is classical everyday physics allowed?

I don't see how this question would be related to the thread. Physics used should be suitable for the topic discussed. If quantum mechanics is relevant then a classical description will fail.

 

[geoelectronics]

The whole thread is about electrons at relativistic speeds. Not that it would matter, at lower speeds it is called cyclotron radiation but it is fundamentally the same concept: Charges being deflected by a magnetic field radiate.The protons are slow but this thread is about the electrons.I don't see how this question would be related to the thread. Physics used should be suitable for the topic discussed. If quantum mechanics is relevant then a classical description will fail.

Please refer back to response #26.

ooops...My error. You are correct, I read the article at the beginning just now. It does say relativistic. My response was to the OP question and was only trying to help him.
Quantum Physics it is. Not my thing. I get it finally, I can't talk quantum and you won't classical physics.

George Dowell
73 DE K0FF

 

[berkeman]

73 DE K0FF

You know that accelerating electrons produces EM radiation (even if not relativistic electrons), or else our antennas would not work...

 

[OmCheeto]

I wish I'd known of the following image before I subscribed to this thread:

[ref]

What a bloody menagerie.
I was contemplating doing the maths, following an electron's path, after it hit the magnetopause, but...
Nope. I'm pretty sure I'd pop one too many blood vessels on my way to the end.

It is fun to think about though.
I find it hard to grasp the magnetopause current.
Aren't the solar wind particles moving REALLY fast?
Isn't the magnetic strength there REALLY weak?

I really do need to do some calculations.

ps. This is a pretty cool image of the magnetopause currents:

[ref]

 

[swampwiz]

Interesting article ...NEW SOURCE OF SPACE RADIATION: Astronauts are surrounded by danger: hard vacuum, solar flares, cosmic rays. Researchers from UCLA have just added a new item to the list. Earth itself.“A natural particle accelerator only 40,000 miles above Earth’s surface is producing ‘killer electrons’ moving close to the speed of light,” says Terry Liu, a newly-minted PhD who studied the phenomenon as part of his thesis with UCLA Prof. Vassilis Angelopoulos.This means that astronauts leaving Earth for Mars could be peppered by radiation coming at them from behind–from the direction of their own home planet.ASA’s THEMIS spacecraft ran across the particles in 2008 not far from the place where the solar wind slams into Earth’s magnetic field. Researchers have long known that shock waves at that location could accelerate particles to high energies–but not this high. The particles coming out of the Earth-solar wind interface have energies up to 100,000 electron volts, ten times greater than previously expected.How is this possible? Liu found the answer by combining THEMIS data with computer simulations of the sun-Earth interface. When the solar wind meets Earth, it forms a shock wave around Earth’s magnetic field, shaped like the bow waves that form ahead of a boat moving through water. Within this “bow shock” immense stores of energy can be abruptly released akin to the sonic boom of an airplane.Liu found that some electrons are shocked not just once, but twice or more, undergoing mirror-like reflections within the bow shock that build energy to unexpected levels. Most of the boosted particles shoot back into space away from Earth.

View attachment 247941

Above: Dr. Terry Liu created this diagram showing the location of the natural particle accelerator and how it sprays radiation into space.​

“Similar particles have been detected near Saturn, suggesting that the process is at work there as well,” says Liu. “Indeed,” adds Angelopoulos, “this type of particle acceleration could be happening throughout the cosmos–from supernovas to solar storms–wherever a supersonic wind hits a barrier.”Meanwhile, back home, Earth-orbiting satellites and departing astronauts have a new source of radiation to contend with. It’s right over their shoulder.Read the original research at Science Advances.
Cheers
Dave

Pardon my dumb question but didn't the Lunar missions go to an altitude of 240K miles?

 

[sophiecentaur]

PS It is good to be suspicious. Question everything, demand proof,
observe everything closely, experiment.

That could sound a bit of a Motherhood and Apple Pie thing (gotta be good) but, in practice, proofs of modern Scientific advances are probably far too hard for your average reader (me too) to appreciate and experiments often cost thousands or millions of quid to carry out. When you get down to it, we have to accept the authority of peer reviewed papers and credible magazines (sometimes PF is a good start).