units of Lorentz force

Open andrewgiuliani opened this issue 8 months ago • 3 comments

https://github.com/hiddenSymmetries/simsopt/blob/706cb1d4f32d0310da2c11a7393d7f2127865637/src/simsopt/field/force.py#L81

Can the units of F be clarified? is it N or N/m?

May 12 '25 20:05 andrewgiuliani

The lorentz force on a particle is qv x B Newtons where qv has units (Coulombs meter/sec). When computed for a coil current density, the force density is JxB Newton/meter, since the current density, J, is measured in Amperes (Coulombs/sec). The local force would JxB dl Newtons and the total force on the coil would be something like int JxB dl Newtons. The documentation is updated in PR 509, see the coil_force method.

May 15 '25 14:05 mishapadidar

@andrewgiuliani should we close this?

Jun 12 '25 14:06 mishapadidar

Not yet, the improved documentation isn't merged into master yet

Oct 17 '25 22:10 andrewgiuliani