Electric field calculations for a spherical grid

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Discussion Overview

The discussion revolves around calculating the radius required to achieve a specific electric field strength of 1 x 106 V/m on the surface of a spherical inner grid within a conductive vacuum chamber. Participants explore various methods and considerations related to this calculation, including voltage, chamber dimensions, and the nature of the grid.

Discussion Character

  • Technical explanation
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant seeks assistance in calculating the radius needed for a specific electric field strength, expressing uncertainty about the equations used.
  • Another participant questions the purpose of achieving such a high electric field, suggesting it may relate to amateur fusion.
  • Participants discuss the importance of the voltage and the radius of the vacuum chamber in determining the sphere's size.
  • Concerns are raised about the effectiveness of using a wire mesh for the grid, with assertions that the field strength would be influenced more by the wire's radius than the sphere's radius.
  • A participant clarifies that they are using standard wire loops rather than a wire mesh, which prompts further discussion on the implications for field strength.
  • Calculations are provided indicating that with a 40 kV DC voltage and a 5-inch chamber radius, a sphere radius of 85 mm is necessary to maintain the desired electric field strength.
  • One participant acknowledges a misunderstanding regarding the grid's geometry, realizing that approximating it as a sphere was incorrect due to its wire composition.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of the proposed grid design and the implications of using wire versus a solid sphere. There is no consensus on the best approach to achieve the desired electric field strength, and multiple competing perspectives remain.

Contextual Notes

Participants mention specific voltage levels and dimensions, but there are unresolved assumptions regarding the grid's configuration and its impact on the electric field calculations.

Jz21
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TL;DR
I need help calculating the radius required to achieve a electric field strength of 1 x 10/6 v/m on a spherical grid inside a vacuum chamber
Hello, I need some help regarding how to calculate the needed radius to achieve 1 x 10/6 v/m on the surface of a spherical inner grid, inside a conductive vacuum chamber. I have used various equations, however I don’t know if they are very good and would like to know other methods. Thanks!
 
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Jz21 said:
TL;DR Summary: I need help calculating the radius required to achieve a electric field strength of 1 x 10/6 v/m on a spherical grid inside a vacuum chamber

Hello, I need some help regarding how to calculate the needed radius to achieve 1 x 10/6 v/m on the surface of a spherical inner grid, inside a conductive vacuum chamber. I have used various equations, however I don’t know if they are very good and would like to know other methods. Thanks!
Woo-wee. 1MeV/m -- whatcha' tryn' to do?
 
A lil bit of amateur fusion, that’s all
 
Jz21 said:
Hello, I need some help regarding how to calculate the needed radius to achieve 1 x 10/6 v/m on the surface of a spherical inner grid, inside a conductive vacuum chamber.
If the walls of the chamber are smooth, without projections, then knowing the voltage, you must place a sphere in the chamber that has a maximum diameter consistent with that voltage gradient.

What is your working voltage?
What is the radius of the vacuum chamber?
 
Just a lil bit of fusion, nothing else
 
Jz21 said:
spherical inner grid
If you mean a wire mesh. I can tell you right now that this isn't going to work.

The field near the wire will be driven by the radius of the wire, not the radius of the sphere. That will be maybe two orders of magnitude greater, and the wire will not survive.
 
Sorry, I didn’t thought I didn’t reply to the other reply, my bad. I am working with 40 kv dc, and the radius of the chamber is 5 inches. There are also no projections, with only a feed through stalk.
 
Vanadium 50 said:
If you mean a wire mesh. I can tell you right now that this isn't going to work.

The field near the wire will be driven by the radius of the wire, not the radius of the sphere. That will be maybe two orders of magnitude greater, and the wire will not survive.
It is not wire mesh, but just standard wire loops.
 
Vanadium 50 said:
If you mean a wire mesh. I can tell you right now that this isn't going to work.

The field near the wire will be driven by the radius of the wire, not the radius of the sphere. That will be maybe two orders of magnitude greater, and the wire will not survive.
Oh ok I see what you mean.
 
  • #10
Jz21 said:
I am working with 40 kv dc, and the radius of the chamber is 5 inches.
40 kV, radius = 5".
5" = 0.125 metre.

1 MV/m is 1 kV/mm, so there needs to be a gap of 40 mm between the chamber wall and the sphere.
The sphere radius will be (125 mm - 40 mm) = 85 mm, or 170 mm diameter = 6.75" diameter. It will need to have a smooth surface.

The support stalk for the sphere will need to be carefully constructed to prevent voltage breakdown along its surface.
 
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  • #11
Baluncore said:
40 kV, radius = 5".
5" = 0.125 metre.

1 MV/m is 1 kV/mm, so there needs to be a gap of 40 mm between the chamber wall and the sphere.
The sphere radius will be (125 mm - 40 mm) = 85 mm, or 170 mm diameter = 6.75" diameter. It will need to have a smooth surface.

The support stalk for the sphere will need to be carefully constructed to prevent voltage breakdown along its surface.
Thank you. But I now realize I was going about it all wrong. I was approximating the grid as a sphere as it forms a sphere, but is still made of wire. So now I know we’re to go.
 

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