Short Gun Research Articles

New types of crossed field electron guns

A new analytical method of designing M-type crossed field electron guns will be described. These guns are based upon an exact space charge flow solution obtained a number of years ago by Pembank, Brillouin and others. The actual design procedure is essentially the same as for Pierce Guns, and the precise electrode shapes are obtained by a method of conformal mapping and a subsequent numerical calculation. Two types of guns result from this procedure. The first, somewhat similar to the French has been constructed and extensively studied. This gun is characterized by an almost complete absence of sole current. Approximate expressions relating current, voltage and magnetic field have been derived for this gun and experimental values are within a few percent of these calculations. Visual observations indicate the shape of the beam in the gun to be essentially as predicted by theory. A convergence of approximately 7:1 has been obtained with this gun. A second type of gun, based on an approximation to the exact flow solution is possible. This gun is characterized by an extremely high convergence and operates at a somewhat higher magnetic field than the short gun. A gun of this type has been constructed and appears to give a fairly well defined beam with approximately the predicted current.

A design method for crossed-field electron guns

A design method for crossed-field guns based on a space-charge-flow solution in crossed fields is given. By using the method of analytic continuation in the complex plane, it is shown that it is possible to find the exact form of the electrodes required The design results in a gun similar to the French "short gun" with the great advantage that the current emitted from the gun and the current density at the cathode can be predicted. It is also shown that by making certain approximations to the exact space-charge-flow solution, a new type of gun can be designed, a "long gun" which can have extremely high convergence. The theory for this latter gun is extremely simple and the electrode shapes can be given entirely in analytic form.

A Short Gun, Throwing a Heavy Sharp-Edged Discoidally-Formed Projectile

A Short Gun, Throwing a Heavy Sharp-Edged Discoidally-Formed Projectile