Is it possible to create an external electric field using a toroid?

Question

I would like to create a directional, "external" electric field.

For example, a solenoid creates an "external" magnetic field in one direction(coming out of the ends of the solenoid). I would like to do the same with an electric field.

This diagram below shows how a toroid could create an external electric field:

Electric fields are only generated from changing magnetic fields, so by applying an alternating current to the toroid, I change the magnetic field inside the toroid, which should create an electric field.

Is this possible to create a reasonably strong electric field with a toroid? (Stronger than say, the E field from just current flowing through a wire).

Answer 1

Firstly the magnetic field described in the question

In a solenoid yes, the magnetic field comes out (and back in) at the ends of the solenoid but with a toroid (which doesn't have ends by definition), there can be no magnetic field exiting theoretically. Of course there are small amounts of flux that are still measurable close by the toroid but these are not significant.

Is this possible to create a reasonably strong electric field with a toroid? (Stronger than say, the E field from just current flowing through a wire).

The strong E field usually associated with (say) a quarter wave dipole antenna is due to standing waves making the tip of the antenna produce large "resonant like" voltages. This can generate a huge electric field and will, due to the antenna capacitance to its opposite end (ground on a quarter wave dipole), can produce significant currents that give rise to a magnetic field hence the beginning of the creation of an EM wave.

To answer your question I don't see how strong electric fields are generated with a toroid compared to a regular antenna.

At the end of the above quote, you say: -

E field from just current flowing through a wire

An E field is due to the voltage not the current.

Answer 2

Well, I think you can. But you have to wind the copper wire around the outside or inside "border" of the toroid. Imagine you have a 10 centimeter "transformer iron core" toroid or one made of that ferrite thing. Then you wind a 12 centimeter toroid with copper wire and put the first toroid inside it. By winding the wire on the ring itself, probably it won't produce much of a external field. If you wind a copper coil "on air" and put a toroidal core inside and outside too, maybe you can achieve some power. If you manage to mill a slot around the toroid, you may get the most power. The field will be strong towards the cut. I mean, to outside it.