Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: shein on 05/10/2008 11:16:09

Title: How can the path of an electron be controlled?
Post by: shein on 05/10/2008 11:16:09

shein asked the Naked Scientists:

How can electrons be bent?
How can electrons be bent more?

What do you think?

Title: How can the path of an electron be controlled?
Post by: graham.d on 05/10/2008 14:18:59

An electron has charge so an electric field will accelerate it in the direction of the field. To be pedantic, as the electron has a negative charge convention would have it that it is in the opposite direction to the field. If the electron is moving, then a magnetic field will accelerate it in a direction perpendicular to its direction of motion and the field. In both cases the strength of the field governs the amount the electron will accelerate. Both these effects are used to direct an electron in a Cathode Ray Tube, for example, as would be used in TVs and computer monitors before the advent of flat screen devices.

Title: How can the path of an electron be controlled?
Post by: DoctorBeaver on 05/10/2008 14:26:04

Is it the same principle for particles in accelerators?

Title: How can the path of an electron be controlled?
Post by: syhprum on 05/10/2008 20:10:15

I am sure I am telling my granny how to suck eggs!
Particle accelerators use a combination radio frequency fields to accelerate the the electrons or other charged particles and a series of static magnetic fields to bend the path of the particles and focus them into a fine beam. 

Title: How can the path of an electron be controlled?
Post by: DoctorBeaver on 06/10/2008 11:54:00

I didn't know about the radio frequency fields. Thank you.

Title: How can the path of an electron be controlled?
Post by: syhprum on 06/10/2008 17:28:30

One of the advantages of operating at a low enough temperature (1.9°K) for the magnets also means that the resonant cavities energised at radio frequency are also superconducting reducing the power that must be generated by the Klystrons to about 10 MegaWatts in the case of the LHC.

Title: How can the path of an electron be controlled?
Post by: DoctorBeaver on 06/10/2008 18:13:58

Is that a continuous 10MW? Can you put that into perspective against domestic consumption?

Title: How can the path of an electron be controlled?
Post by: lyner on 06/10/2008 18:58:25

One home (mine) used about 750kWh last quarter. That's about  8.4kWh every day, or an average  load of around only 330W.
Not allowing for peak demands, or assuming we all spread out our demand to produce a steady requirement 10MW would serve 30,000 homes. BUT my peak demand could well be at least 10kW and so could everyone else's, so that could mean a capacity of 10MW would only serve 1,000 homes. The 'real' answer is somewhere in between.
The LHC isn't running all the time, of course.

Title: How can the path of an electron be controlled?
Post by: DoctorBeaver on 06/10/2008 19:20:52

Thank you

Title: How can the path of an electron be controlled?
Post by: syhprum on 06/10/2008 21:46:08

I have seen the power consumpsion of the whole machine put at 120MW.
I am not sure how this breaks down, I would think a great deal goes on refrigeration ,then there is magnet power, computing, and general housekeeping.
120MW is a lot less than a jumbo jet uses.