Teltron Dual Beam Tube ref U19170

The Dual beam D series part evacuated electron tube, filled with neon at low pressure, with tangential and axial electron gun for determining specific charge e/m from the diameter of the filament beam in the case  of tangential bombardment and a perpendicularly ed magnetic field. The electron paths are rendered visible in the form of fine luminescent beams through impact excitation of the neon atoms