Abstract: A magnetic deflection system comprising a cylindrical magnetic circuit which surrounds two pairs of saddle-shaped deflection coils, horizontal and vertical, fitted coaxially with the magnetic circuit and at right angles to each other, each said coil being provided with a longitudinal portion and a lateral portion which mate together through a jointing area, each said jointing area having its cross-section of a variable thickness, which cross-section diminishes from a maximum value measured along a section through a boundary line of the jointing area limiting either the longitudinal portion or the lateral portion to a minimum value measured along a diagonal section that passes through the jointing area at right angles to the deflection plane of the electron beam.