Discussion Forum

Hi,

I have a series of rods arranged in a circle (an octagon). Each rod is about 1 m long. I am sending in a time-varying potential to each of the rods (each rod is π/4 out of phase with its neighbor, going along the circle until we come back to full 2π).

Since each rod has about a 44 pF capacitance with the rest of the world, it takes some current to charge up the rods. I am charging the rods at every 10 cm. At each of these charging points, there will still be some charging current flowing from the charging point to the rest of the rod.

The charging currents generate magnetic fields, and I am interested in the magnitudes and spatial dependence of the fields. I tried using the following model: 1. 8 rods of length 10 cm, diameter 1 cm, material 316LN; enclosed by a cylinder of diameter 8" and height 10 cm, material Air. 2. Study: Time dependent. 3. Physics: Magnetic fields. 4. Periodic boundary condition on the flat faces of the enclosing cylinder. 5. Sending in a time-varying current from both ends of each rod.

COMSOL tells me that:

The Current excitation is not supported for Single conductor coils in time dependent studies.

and I am not entirely sure how I should go about doing this.

Can someone point me to a possible way I can model the time-varying B-fields due to the time-varying charging currents in the rods in COMSOL?