JPH02242549A - Gas discharge device - Google Patents

Abstract

PURPOSE: To increase the amount of ionizing in a device by making a path length of a charged particle of discharge when a magnetic field exists longer than that when a magnetic field does not exist. CONSTITUTION: A magnetic field generated in a thyratron by a magnet 5 is substantially parallel in the direction perpendicular to surfaces of a cathode 3 and an anode 2 as shown by a broken line indicating a line of magnetic force. Electrons are emitted from the cathode 3 while operating the thyratron. The electron which does not progress in the direction parallel to the magnetic field traces a spiral path around the line of magnetic force, and is pulled to a grid by an electric field applied to the grid. Each electron which progresses along the spiral path has a lot of chances to do ionized collisions when it moves toward the grid 4 and the anode 2. As a result, an ionized density in the device increases.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to gas discharge devices, and more particularly, but not exclusively, to thyratrons.

Prior art thyratrons generally include an anode, a cathode, and an intervening grid structure housed within a gas-filled tube. When attempting to establish continuity through the device, a discharge is created within the Sila I Ron by applying an appropriate voltage to the control grid.

SUMMARY OF THE INVENTION The present invention provides an improved gas discharge device.

According to the invention, the device comprises an anode, a cathode and means configured to generate a magnetic field within the device.
A scum discharge device characterized in that the charged particles of the discharge are made to have a longer path length in the presence of a magnetic field than in the absence thereof, thereby increasing the amount of ionization within the device. is provided. A charged particle traveling parallel to the magnetic field lines experiences zero force. Charged particles that do not travel parallel to the lines of magnetic force are subjected to a force perpendicular to their direction of travel and to the lines of magnetic force. This causes the particles to follow a curved path relative to the magnetic field lines.

Electrons emitted from the cathode in a direction not parallel to the magnetic field therefore travel along a helical path as they travel towards the anode. Therefore, it will have a longer path length when a magnetic field is present than when it is not. This increases the number of collisions that occur and thus increases the ionization density within the device. Therefore, the scum discharge device according to the invention makes it possible to obtain higher ionization densities than those obtainable with conventional devices. This improves the rate of voltage drop after triggering, reduces required trigger energy, and improves cathode life. or,
It has been found that more uniform ionization occurs in the cathode region, and that this ionization extends into regions previously unused in the absence of a magnetic field.

Preferably, the magnetic field is made to be present during switching when current flows between the anode and cathode. That is, a magnetic field is present during the conduction of pulses through the device.

Preferably, the magnetic field has a component substantially parallel to the direction of discharge within the device. This is particularly effective as charged particles traveling in a spiral around the magnetic field component lines tend to be retained within the main discharge region. If the magnetic field has only one component in a direction oblique to the direction of the discharge, the charged particles will tend to be pulled away from the discharge region, thus creating ionized particles in less effective locations. .

The means for generating a magnetic field is preferably a magnetic material, advantageously samarium cobalt, but electromagnets may also be used. In a preferred embodiment of the device, the magnetic material is placed at the anode, but it could also be placed concentrically with respect to the cathode, for example.

The invention can be used particularly effectively when the device is a thyratron. At least a portion of the grid structure is
The magnetic field may be included in a magnetic path forming part of the means for generating a magnetic field.

Several ways of implementing the invention will now be described, by way of example only, with reference to the accompanying drawings.

Referring to FIG. 1, the thyratron comprises a ceramic tube 1 in which an anode 2, a thermionic cathode 3 and a grid structure 4 disposed therebetween are housed. Hydrogen at a pressure of several torr is also contained within the tube 1. A cylindrical samarium cobalt magnet 5 is arranged coaxially around the anode stem outside the tube 1. The part of the magnet closest to the cathode is the south pole and the other end is the north pole. The magnetic field generated within the Zycitron by the magnet 5 is as shown by the dashed line representing the magnetic field lines.
substantially parallel to a direction perpendicular to the surfaces of the cathode and anode. During operation of the thyratron, cathode 3
Electrons that do not travel in a direction parallel to the magnetic field follow a spiral path around the magnetic field lines and are pulled toward the grid by the electric field applied to the grid. Each electron traveling along a helical path will move towards the grid 4 and the anode 2 if it moves in a substantially straight path to the anode 2 (like this in the absence of a magnetic field). have the opportunity to form a larger number of ionizing collisions. The regions of intense glow discharge, which in conventional thyratrons are usually located on one side of the cathode structure, are distributed sufficiently evenly around the cathode in the thyratron according to the invention, improving the utilization of the cathode 3.

Referring to FIG. 2, another thyratron according to the present invention is similar to that shown in FIG.

A magnetic material 6 is arranged coaxially around the cathode 7 and constitutes a pole piece 8 . A portion of the magnetic path is formed by a grid structure 9.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a scum discharge device according to the present invention; and Figure 2 shows In a schematic diagram of another device according to the invention be. 1... 3... 4.9 5... 6... 8... Tube 2...Anode thermionic cathode ・Grid structure samarium cobalt magnet Magnetic material 7...Cathode magnetic pole piece

Claims (9)

[Claims] (1) comprising an anode, a cathode, and means configured to generate a magnetic field within the device, wherein the charged particles of the discharge take a longer path in the presence of the magnetic field than in the absence of the magnetic field; A gas discharge device characterized in that it has a length, thereby increasing the amount of ionization within the device. 2. The apparatus of claim 1, wherein the magnetic field is configured to be present during switching when current is passed between the anode and cathode. 3. The device of claim 1 or 2, wherein the magnetic field includes a component substantially parallel to the direction of discharge within the device. 4. An apparatus according to claim 1, wherein said means configured to generate a magnetic field comprises a magnetic material. (5) The apparatus of claim 4, wherein the magnetic material is samarium cobalt. (6) The device according to claim 4 or 5, wherein the magnetic material is arranged at the anode. 7. The device of claim 1, wherein the device is a thyratron and includes a grid structure disposed between an anode and a cathode. (8) The apparatus of claim 7, wherein at least a portion of the grid structure is included in a magnetic path. (9) The above means configured to generate a magnetic field:
7. A device according to any of the claims, comprising at least a portion of an electrode structure.