Double Fine Beam Tube
Helium filled, partly evacuated electron tube with axial and perpendicular electron guns. The electron beam may be observed as a fine, green beam appearing due to the the impact excitation of the helium/electron collisions.The tangential beam can be deflected by use of Helmholtz coils to produce a completely circular path permitting e/m measurements to be made. Clear free path studies may be made and phenomena such as screen blanking due to charge build up on the screen may be observed. Within the tube are mounted two electron guns perpendicular to one another, with indirectly heated oxide cathodes. The angle of projection from the guns is adjustable by means of miniature deflection plates near the gun outlets, a small potential being applied via 4mm connections at the side of the cylindrical neck. The end of the body has a phosphor coated screen for use with the axial gun. Supplied complete with instructions.
• Anode voltage: max. 100V DC
• Anode current: max. 30mA
• Filament voltage: 7.5V AC/DC
• Deflector voltage: max. 50V DC
• Total length: 260mm approx.
• Glass bulb: 130mm diameter approx.
• Gas filling: Heliuim at 0.1 torr pressure