Electron gun Definition and 29 Threads

An electron gun (also called electron emitter) is an electrical component in some vacuum tubes that produces a narrow, collimated electron beam that has a precise kinetic energy. The largest use is in cathode ray tubes (CRTs), used in nearly all television sets, computer displays and oscilloscopes that are not flat-panel displays. They are also used in field emission displays (FEDs), which are essentially flat-panel displays made out of rows of extremely small cathode ray tubes. They are also used in microwave linear beam vacuum tubes such as klystrons, inductive output tubes, travelling wave tubes, and gyrotrons, as well as in scientific instruments such as electron microscopes and particle accelerators.
Electron guns may be classified by the type of electric field generation (DC or RF), by emission mechanism (thermionic, photocathode, cold emission, plasmas source), by focusing (pure electrostatic or with magnetic fields), or by the number of electrodes.

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  1. S

    Electrical Need advice on building a linear particle accelerator

    I am a freshman in highschool and I plan on building a linear particle accelerator (DTL) I need help finding out how to find the drift tube length. I use the equation V=√(2eV/m) (where V is equal to the velocity. E is the elementary charge of the electron 1.602 x 10^-19. V is the applied...
  2. M

    Why do we need to take the absolute value of charge in an electron gun?

    For part (a) of this problem, The solution is, However, why did they need to take the absolute value of the charge? I thought they could keep the original signs as shown below: Using energy conservation, the electric force dose internal work transferring electric potential energy into...
  3. rsc9421

    A Power consumed by electron gun

    First Assume the following basic circuit: I read in many textbooks that the electrons in the circuit are accelerated by the positive voltage and decelerated by the collisions, so the speed is constant. We also know that the circuit current is I = 10A so the power consumed is P = V * I = 100W...
  4. D

    Exploring Electron Rockets for Interstellar Travel

    Hi all, Why not build an electron rocket? Why won't this idea work? Seems like someone could just hitch an electron gun onto a spaceship. Boom! Electron Rocket. I was thinking about ion thrusters. These use ions to achieve thrust. They are problematic for achieving a high delta V because...
  5. SWKatzen

    Exploring Electron Gun Deflection: Causes and Resources for Understanding

    Hi, I was wondering if anybody knows why the plate in an electron gun is tilted with respect to the electron path? Or has any resources that I could read to better understand? Thanks.
  6. D

    Electron gun in a vacuum -- How hard of a vacuum is needed?

    how high does a vacuum need to be for electron gun to work? for example, will 1 pascal work, will 1 tenth of a pascal work? is there a minimum vacuum for a electron gun to work?
  7. chucrut

    Electron Gun Design - Can Positive Voltage Work?

    Hello, I have a question about electron guns. I have read a lot, and all designs use high NEGATIVE voltage (-1000v for example). Is possible to use high POSITIVE voltage like this drawing?. Or do you think it will not work this way? Considering that all the chamber walls are at ground voltage...
  8. R

    Electron Gun diffraction and undeflected spot diameter

    Hi I am doing an electron gun diffraction right now and I wonder why the angle below is 2 phi. What I think about it that it's actually the results of two waves one is shown below and the other is a wave with the same accident angle but negative "those two rays will be symmetric around the...
  9. J

    B Electron Gun for a Grade 9 Physics Project?

    I am in grade 9 in the IB curriculum and next year I have to do something called a "Personal Project" where I have to make something and explain why I did it. I would like to recreate the double slit experiment. However, I have to obtain a electron gun and they are quite hard to come across. So...
  10. dholbach

    Can a cathode ray tube be made from a light bulb?

    Light bulbs and cathode ray tubes are structurally similar in some respects. For example, both contain a filament -- in the light bulb, the filament heats up to produce light, while in a cathode ray tube, the filament emits electrons, which are then steered into a target (in a CRT TV, the...
  11. O

    Any idea how to bake the column of a SEM?

    I am an undergraduate researcher and my university had an SEM donated to us by DOW chemical. It since has been without power and we have to bake the column and the gun chamber. Contacting the company they estimate $17k to send someone out to do it for us. I'm having difficulty finding material...
  12. P

    How to remove electron gun from a TV?

    I'm trying to reuse an electron gun from an old black & white TV for an art project. I've posted into this forum rather than Electrical Engineering as I think that this is a strictly mechanical matter with no electricity involved. The TV's dead, and all I want is the physical bits of the...
  13. D

    Can a electron gun attract/repel permanent magnet?

    Can it do such a thing or are the particles too small ? If it is possible can I take the electron gun out my cry is you AA batteries?
  14. genxium

    Can I make an electron gun at home?

    I'm quite interested in home-made devices, last year I tried making a sinusoidal wave oscillator at home and succeeded. It feels good to DIY some coarse devices, and recently I'm learning to build a Cathode Ray Tube. However, it's not going successful with me; I would like to build an electron...
  15. S

    Buy High Voltage Electron Guns Up to 40kV - Expert Advice

    Hi folks, In need of some advice. Can anyone recommend any companies selling high voltage electron guns up to 40kV? Thanks!
  16. T

    Up/down electron gun construction?

    up/down electron gun construction?? Greetings! I'm working on a project that Requires a roughly equal number of up and down spin electrons to be injected into a (vacuum or ATP) chamber. Is there a common device that does this? If not, would it be possible to build one and how would it work...
  17. I

    What Voltages Should Be Used for Focus and Deflection Plates in an Electron Gun?

    Hi all, I am making electron gun. I have several High voltage power supply to provide enough voltages to Filament, Anode, Grid, Focus and deflection plates. I want to make electron gun of acclerationg potential of 5-8 KeV. I know I have to give negative supply to cathode or filament. and then...
  18. J

    Is it safe for a 15-year-old to build an electron gun with dangerous elements?

    Im 15 from the U.K and i want to do something with my life. So i jumped to the conclusion of building something, i didnt want something like a cyclotron, but i wanted to start of with something easier such as a electron my goal is to try and build an electron gun. I want to try and make this...
  19. P

    How to Remove Electron Gun from CRT?

    Hey... I was just thinking... Does anyone know how to extract the electron gun from an old CRT so that it is left intact? Basically, I want to remove it so that I can play with the electron beam/use it for other experiments/ etc. Please tell me.
  20. M

    Refocusing of paraxial electron from electron gun

    Homework Statement Electrons emitted with negligible speed from an electron gun are accelerated through a potential difference v along the X-axis. These electrons emerge from a narrow hole into a uniform magnetic field B directed along this axis. However, some of the electrons emerging from the...
  21. C

    How would the electric field look like for an electron gun?

    Homework Statement Sketch to illustrate the device and the role of the electric field for - an electron gun Homework Equations N/A The Attempt at a Solution http://i.imgur.com/J8Diu.png
  22. E

    Determine the kinetic energy of the electron as it leaves the electron gun

    Homework Statement In an electron microscope, there is an electron gun that contains two charged metallic plates 2.75 cm apart. An electric force accelerates each electron in the beam from rest to 8.90% of the speed of light over this distance. (Ignore the effects of relativity in your...
  23. C

    Using Ni-Chrome Wire for Heated Cathode in Electron Gun

    can i use ni-chrome wire , for my heated cathode on my electron gun , using Thermionic emission , or what would be a better filament to use.
  24. S

    Electron gun design using faraday cage like setup

    I have designed an electron gun that incorporates a faraday cage setup and I would like anyone's opinion if this setup could actually work. See attachment for image or here is a link to the image of the electron gun http://yfrog.com/j7electrongundesignbj Explanation of image There is a...
  25. D

    What angle should an elctron beam leave an electron gun?

    [b]1. At what angle should a 1kV electron beam with a total current of 1mA leave an electron gun in order that the cross section of minimum diameter will occur on a screen 25cm away? The original diameter of this beam is 2mm. [b]2. Cannot find equations in book or notes anywhere...
  26. S

    Calculating the electric field in an electron gun

    Homework Statement I have given a cathode and a anode being -1000V and 1000V each respectivily I know the distance between the cathode and anode its 3mm What I have to do now is calculate the electric field between the cathode and anode and use that to find the acceleration of an electron...
  27. M

    Electron Gun Grounding: Best Practices for Photoemission Experiments

    Will an electron gun firing electrons into the air end up having no more electrons to fire eventually?
  28. F

    Q26: Electron Gun Physics - Kinetic Energy, Force, Acceleration & Time of Flight

    Q26. In the neck of the picture tube of a certain black-and-white television set, an electron gun contains two charged metallic plates 2.80 cm apart. An electric force accelerates each electron in the beam from rest to 9.60% of the speed of light over this distance. (a) Determine the kinetic...
  29. C

    How does an electron gun shoot a stream of electrons?

    Electricity is the movement of electrons from attom to atom but how are streams of electrons shot through the air to hit a phosphor screen in a TV or monitor by an electron gun? I have heard of electrical arc's but when those are preformed there are usually sparks going every where so I know it...
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