# High voltage and magnetic fields

I have a pool of mercury contained within a sealed glass tube. There are two electrodes placed within the tube. The left hand side electrode contacts the mercury. There is a gap of almost 1cm from the right hand side of the mercury pool to the right hand side electrode. A high voltage (approx 10Kv current is applied, the Hv input electrode connected to the left hand side electrode and the ground connection to the right hand side electrode.

An 555 oscillator circuit drives the Hv and the frequency of oscillation can be altered by a 50KOhm pot. A strong Nd magnet is placed alongside the tube, the North pole (of the magnet) is facing the tube. If the oscillation frequency is set at the lowest possible position and no magnetic field present the arc is in a straight line. When a strong magnet is put into the position stated above the arc curves strongly towards the magnet (this is expected of course) and now if the frequency of oscillation in the primary coil is increased slowly the arc can be made to also oscillate in a wide fan-like pattern.

I realise many things can be happening within the tube: namely ionized Hg (there is heating of course above ambient due to the flow of current, those ions must be? under the affect of the magnetic field when present (sort of like a sputter coater) The power supply is 12VDC.

I do not see an oscillation of the pool of mercury as current obviously passes through it and must be setting up a magnetic field? My question is this a kind of Hall Effect or is it a little more complicated. I enclose a schematic of the setup. The footage (not shown) does show (probably some sort of plasma?) moving in small jets towards the magnetic field).

• It would make your question easier to read if you broke it up into paragraphs. Oct 23, 2019 at 16:17
• Done! Many apologies! Also I would add that I would have expected the curvature to be for the magnetic south pole in this setup for the Hall Effect. Oct 23, 2019 at 16:49

The fact that the arc curves in the magnetic field is just the effect of the Lorentz force on the free carriers that form the arc. $${\bf F} = q{\bf E} + q{\bf v}\times{\bf B}$$.