Measuring Tiny changes in Electric Field Strength

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Discussion Overview

The discussion revolves around methods for measuring minute changes in electric field strength, exploring various experimental approaches and theoretical considerations. Participants share ideas related to electron and ion trapping, as well as alternative methods for achieving high sensitivity in electric field measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests creating a cost-effective electron trap to measure tiny changes in electric field strength, inspired by a Harvard experiment isolating a single electron.
  • Another participant proposes using oil droplets in an electric field, referencing Robert Millikan's experiment, but acknowledges limitations due to the mass of the droplets and air viscosity.
  • Concerns are raised about the feasibility of using magnets due to their poor temperature coefficients and drift compared to electric fields.
  • Some participants highlight the complexity and cost of building a Penning trap, noting that it requires significant expertise and equipment investment.
  • One participant mentions that trapping single electrons is very difficult and suggests that trapping ions may be a more viable alternative, as it has been successfully done by various research groups.
  • There is an ongoing request for additional ideas or methods to measure electric field changes, indicating openness to new approaches.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and practicality of various methods for measuring electric field strength. While some agree on the challenges of trapping electrons, others propose alternative methods without reaching a consensus on the best approach.

Contextual Notes

Participants note the high costs associated with the necessary equipment and the expertise required for the proposed experiments, indicating that many methods may not be accessible for casual experimentation.

Who May Find This Useful

This discussion may be of interest to researchers and students in experimental physics, particularly those focused on electric field measurements and particle trapping techniques.

jonlg_uk
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Hi all I am looking to measure minute changes in electric field strength. I found this article http://www.physorg.com/news74876394.html" which describes how scientists at harvard isolated a single electron in a highly evacuated, absolute zero chilled chamber and manipulated its movement using electrodes.

I have been thinking about doing something similar to solve the problem of measuring such tiny changes in electric field. I would like to create an electron trap, cost effectively. I basically need a FIXED amount of charge in the form of a "ball of electrons" or a "ring of electrons". I then want to control the movement of the electrons using electrodes like the scientist did. Does anyone have any ideas of how to do this cost effectively.

Any one got any other ideas how to measure these minute changes in electric field strength?
 
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Maybe you could do what Robert Millikan did and spray oil droplets into an electric field and balance the charges against gravity. And then maybe push them around with a magnet. I know this isn't an electron trap but it might help. Or maybe if you have an electron gun accelerate the electrons over an electric potential and push them around using the Lorentz force . These are just some ideas .
 
cragar said:
Maybe you could do what Robert Millikan did and spray oil droplets into an electric field and balance the charges against gravity. And then maybe push them around with a magnet. I know this isn't an electron trap but it might help. Or maybe if you have an electron gun accelerate the electrons over an electric potential and push them around using the Lorentz force . These are just some ideas .

Hi cragar, thanks for your ideas, that is outside the box thinking. Unfortunately the Millikian oil drop experiment has fundamental problems associated with it. First of all you are using a heavy particle i.e an oil drop with a radius of ~0.1um. That adds to the momentum at which it travels at and hence the sensitivity is limited. Also there is a limiting factor of air viscosity.

Also using any type of magnets are out of the question as they have poor temp coefficents and drift more than the electric fields.

Any one got any more ideas?
 
What do you mean by "cost effectively"? The kind of experiment you are describing (I guess you need a Penning trap of some sort) requires fairly well-equipped lab and a lot of expertise; it is most definitely not something you can try at home, the vacuum equipment alone will cost you tens of thousands of dollars.
 
f95toli said:
What do you mean by "cost effectively"? The kind of experiment you are describing (I guess you need a Penning trap of some sort) requires fairly well-equipped lab and a lot of expertise; it is most definitely not something you can try at home, the vacuum equipment alone will cost you tens of thousands of dollars.

Yeh something like a penning trap would be ideal. However it would need to be custom built to adapt a range of electric fields. I would want to measure the variations in fields created by say a 1kV DC power supply right upto say a 60kV.

By cost effectively I don't want to spend more than $15k dollars ...
 
Does anyone have any other ideas? I am open to all types of new and existing methods
 
Does anyone have any other ideas? I am open to all types of new and existing methods
 
Trapping and controlling single electrons is VERY difficult, and also costly. At the end of the article you linked, they even state it took 20 years and half a dozen PhD's to do it. The reason is that an electron is so light, that basically anything you can think of disturbs it so much it won't get trapped, let alone cooled properly.

I would say that you are much better off with trapping ions, rather than electrons, as this is much easier and has been done by a lot more groups. Ion traps have also been shown to be useable for detecting electric fields with high precision, although the voltage you specified is fairly large. Just note however, that even ion trapping takes a good amount of expertise and money to get going, so it won't be easy either.
 
Thanks for your replies, I am aware of the difficulties of ion/electron traps. Does anyone have any other ideas apart from an ion traps?
 

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