Coaxial diode with magnetic insulation

 

(57) Abstract:

Usage: in accelerator technology when creating a pulsed high-current relativistic electron accelerators microsecond range. The inventive cathode is made in the form of a disk wedge-shaped cross-section with a radially directed outward with a sharp edge, the end surface of the cathode is made in the form of a continuous flat circle and covered with a dielectric film, complicating an explosive issue, and the geometry of the solenoid is provided with a reverse current of the diode. Reverse electron current of the diode forms a plasma addressed to cataloguerates cathode surface, and the outer boundary of this plasma is electron emitter direct electron flow. Plasma on the front surface of the cathode is not formed due to the presence of the dielectric coating, and the amount of plasma generated on the side surface, is insignificant due to the small area of the latter. Thanks to its significantly improved the stability of the transverse profile of the current density of the electron beam during the microsecond time intervals. 3 Il.

The invention relates to accelerator technology and can be used to create high-current relative is on the accelerator of relativistic electron beam (REB) microsecond duration, containing catalogization with a fixed explosive-emission cathode located in a vacuum chamber inside the solenoid [1]

The closest technical solution of the invention, selected as a prototype, is coaxial diode with magnetic insulation (CDMI) containing catalogization with a fixed cylindrical explosive-emission cathode located in a vacuum chamber inside the solenoid [2]

The shortcoming of the prototype is that the emitting electrons, the plasma-side surface of the cathode, extending normal to the surface, i.e., across the magnetic field, increasing the outer radius of the tubular beam. This is due to the fact that the plasma moves in the direction opposite to the pressure gradient, therefore, under pressure from neighboring areas (lateral and inner radius) formed on the surface extended along the length of the cathode plasma is extruded in the direction of increasing radius. This mechanism determines the scattering length, i.e. the distance that shifts the plasma during the pulse duration.

An object of the invention is to stabilize the transverse profile of the current density tubular EOI cathode surface, that can be scattering across the magnetic field of the plasma emitting the electrons in the direction of the electron beam and the elimination of explosive emission on the end surface of the cathode.

This is achieved by the fact that the cathode is made in the form of a disk wedge-shaped cross-section with a radially directed outward with a sharp edge, the face surface of which is made in the form of a continuous flat circle and covered with a dielectric film, complicating the explosive emission, and the size and number of turns of the solenoid is selected from the conditions for the reverse current of the diode.

Comparative analysis of the prototype shows that the claimed CDMA differs significantly lower area of the side surface of the cathode, from which you can issue that allows to conclude that the criterion of "novelty."

Long known different shapes diode with ostrinia (blade) cathodes. In some cases, the edge is directed directly toward the anode, which is also the collector of electrons. In the case of CDMA electrons fly in the direction of the collector parallel to the surface of the anode, not approaching it. But in any case the electron beam is formed in the direction of the tip. Even the tip is made for tohusam case, the direction of current flow perpendicular to the direction of the tip on the anode tube. The sharp edge is used to minimize (and ideally completely prevent) the emission of electrons (hence, heating of the surface, the formation of plasma, its expansion, and so on).

When comparing the proposed solutions claims with other known technical solutions in this field of engineering not found solutions with similar features and decisive similar technical tasks, which allows to conclude that the criterion of "inventive step".

In Fig. 1 presents CDMI, General view; Fig. 2 shows the radial distribution of current density of the electron beam at different points in time; Fig. 3 shows the same distribution for a cathode, the respective prototype.

CDMI contains explosive-emission cathode 1, is made in the form of a disk wedge-shaped cross-section with a radially directed outward with a sharp edge and a flat end surface covered with a dielectric film. The cathode is located on catopocerinae 2 in the vacuum chamber 3, which also serves as the anode. A magnetic field of 1 Tesla area of the cathode is generated by the solenoid 4. Magnetic power tube 5, which is determined by the outer radius of the cathode, indicated by the dotted line is Elektronnaya issue their heats the conductive surface and formed as a result of this plasma is further emitter of electrons.

On the end surface of the cathode is covered with a dielectric, electron emission and, consequently, the formation of plasma very difficult (it can be some metals, titanium oxide, and others). Used anodizing aluminum dural surface of the cathode. For a similar purpose were used the layer thickness of 50-100 μm, achieved almost the desired result with layer thickness of 10 μm. Because any inhomogeneity on the surface of the cathode (for example, the inner edge of the annular cathode) increases the electric field strength and may cause a break of the film, the mechanical surface made in the form of a solid disk.

The amount of plasma generated on the side surface of the cathode is negligible due to its small area: sharp edge.

The reverse current of the diode will be different from zero if the magnetic lines of force 5 directed towards katalogizacija not cross its surface. In this case, the free electrons propagate along the magnetic field and can leave the chamber wall. This process is well known, it leads to loss of energy of the accelerator and typically from him trying to get rid of. The magnitude of the reverse current is governed by the value of the minimum lazmi on the reverse (opposite end) of the conductive cathode surface. Plasma propagates in the same direction, and forming a return current electrons (ambipolar mechanism) at a rate of 107cm/S. the thickness of the plasma tube increases with time due to reduction of its inner radius, along with the reduced inner radius and increases the thickness of mitterolang with electronic flow, forming a reverse current diode. This mechanism is completely analogous to the dynamics of the plasma and RAP with the outer conductive surface of the cathode in the prototype.

The outer radius boundary of the plasma is an electron emitter, which can be distributed not only in the opposite direction (to the left in Fig. 1), but also to form a straight line, working current of the diode (right). Thus the outer boundary of the plasma (and RAP) almost does not expand. The inner boundary RAP stabilized so that the end surface of the cathode, emitting virtually no, as covered by the dielectric and the inner layers of the emitting plasma (left from the cathode) are escaped by the cathode.

Radial profile of the current density REP was measured partitioned manifold by a receiver placed at a distance of 30 cm from the cathode 1. The results of the measurements are presented in Fig. 2. The histograms of Pokuttya (see Fig. 3) the effect of radial expansion of the cathode plasma is completely eliminated, while the main current is concentrated in the tube with a wall thickness of 3 mm

Thus, the use of the invention allows to obtain a tubular high-current REB microsecond duration, in which the radial profile of the current density remains practically unchanged during the pulse.

Coaxial diode with magnetic insulation of high current pulsed accelerator of relativistic electron beam of microsecond duration, containing catalogization with a fixed explosive-emission cathode located in a vacuum chamber inside the solenoid, wherein the cathode is made in the form of a disk wedge-shaped cross-section with a radially directed outward with a sharp edge, the end surface of which is made in the form of a continuous flat circle and covered with a dielectric film, complicating the explosive emission, and the size and number of turns of the solenoid is selected from the conditions for the reverse current of the diode.

 

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