JPS6177240A - Soft x-ray generation device - Google Patents

Abstract

PURPOSE:To enable stable discharge even in case of big current discharge by so constituting as to separately supply a fixed amount of a working material measured in advance on the electrode surface. CONSTITUTION:When a piston 7 is pulled up by an electromagnetic coil 8, one grain of metal grains enters a thin hole 6 from a thin hole 9 of a branch. When the piston 9 goes down, the metal grains are pushed out downward for being pushed between the third electrode 12 and the main electrode 1. The hole diameter of the third electrode 12 is small so that the metal grains do not fall into a container. Main voltage is left being applied between the electrode 1 and the electrode 2 and the voltage for a trigger is applied between the third electrode 12 so that a current flows because both electrodes 12 and 1 are short-circuited by metal grains while the metal grains are melted for partly being evaporated and jetting only from a hole of the electrode 12. Said weakly ionized metal vapor is jetted between said hole and an opposed electrode 2 thus generating main discharge between the electrodes 1 and 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vacuum spark type soft X-ray generator, and particularly to means for stably supplying ionized substances.

[Background of the invention]

Among plasma X-ray sources that use a capacitor charged at a high voltage as a power source and generate soft X-rays through high-speed, large-current discharge, the vacuum spark method uses an electrode material as an ionized material while keeping the inside of the discharge tube in a vacuum. Since the discharge switch connected to the power source can be omitted, the device can be made compact, highly reliable, highly efficient, and inexpensive. However, since this type of electrode material is used for the ionized gas, there is a problem in that the electrode is worn out and the interior of the discharge tube is contaminated by the electrode material.

JP-A-57-191948 discloses a method of using a liquid as an ionizing substance to reduce the consumption of electrodes.

This method heats a metal with a low melting point to make it liquid, and supplies it to the surface of the electrode through a hole in the center of the electrode.The liquid metal is ionized and consumed bone is continuously replenished through the hole.

Although this method is suitable when the discharge current is sufficiently small, it is not suitable for pulsed large current discharge reaching several tens of kA for the following reasons. (1) In a large current discharge, liquid metal in a long and narrow conductive path easily boils at areas other than the electrode surface due to Joule loss. This problem is particularly serious in areas where the resistance is high, such as the contact area between the liquid metal and the power supply line. (2) In the area where the liquid metal has vaporized, arc discharge occurs, so the pressure increases significantly, and all the liquid metal in the discharge path is scattered into the discharge path and the liquid metal reservoir. (3) In order to flow a large current, plasma must be formed quickly. To do this, the tip of the electrode should be small enough so that the metal evaporates directly. To achieve a sharp tip using a liquid metal with high surface tension, either apply a high voltage between the electrodes or wet the surface of the sharp mandrel with the liquid metal. The former method has the risk of inducing a main discharge, and the latter method has the problem of not being able to supply the amount of liquid metal required for large current discharge.

[Purpose of the invention]

One object of the present invention is to provide a soft X-ray generator that uses a vacuum spark method using a metal with a relatively low melting point as an ionized substance and can stably supply ionized metal to the electrode surface during a pulsed large current discharge operation. It's there.

[Summary of the invention]

In order to achieve the above object, in the present invention, a soft X-ray generator is constructed by adding a means for separately supplying metal particles measured in an amount necessary and sufficient for one discharge to the electrode surface. It is characterized by

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. A first electrode 1 and a second electrode 2, which also serve as an outer case, are opposed to each other. There is an insulator 3 between the electrodes 1 and 2, which together form a discharge vessel. Exhaust hole 4 inside the container
Or it is evacuated by 5. There is a pore 6 in the center of the electrode 1, in which a piston 7 is installed. The piston 7 is moved downward by the electromagnetic coil 8. Another pore 9 branches off from the center of the pore 6, and this pore 9 is connected to a metal reservoir 10. The working metal in the metal reservoir 10 is
It is made into granules in the amount necessary and sufficient for one discharge.

A third electrode 12 is installed close to the tip of the electrode 1 with an insulator 11 in between. A hole is also provided in the center of the insulator 11 and the third electrode 12 in alignment with the pore 6 of the electrode 1. However, the hole of the third electrode 12 is narrower than the diameter of the pore 6. The center of the second electrode also has a cavity 13, and an X-ray extraction window 14 fitted with a beryllium plate is installed in the center.

The operation is as follows. Piston 7 by electromagnetic coil 8
When the metal particle is pulled upward, one metal particle enters the pore 6 from the pore 9 of the branch. When the piston 7 descends, the metal particles are pushed downward and pushed between the third electrode 12 and the main electrode 1. At this time, since the hole diameter of the third electrode 12 is small, metal particles do not fall into the container. A main voltage is applied between electrode 1 and electrode 2. A trigger voltage is applied between the third electrode 12 and the electrode 1. Then, since the two electrodes 12.degree. 1 are short-circuited by the metal grains, a current flows, and some of the melt in the metal grains evaporates. At this time, since the upper part of the steam is blocked by the piston 7, the steam is ejected only from the hole in the electrode 12.

This weakly ionized metal vapor is ejected between the counter electrode 2 and a main discharge between the electrodes 1 and 2.

An insulator 3 separating the case 1 and the electrode 2 is designed to wrap around the electrode 2 in the center. The center electrode 2 is the outer case 1
Since the structure is such that heat is maintained against the central electrode 2, the surface of the insulator 30, which is surrounded by the central electrode 2, is kept at a higher temperature than the outer case 1 due to electrode loss. The ionized substances ejected between the electrodes and scattered in all directions adhere to the inner wall, but due to the temperature difference, they condense on the outer case 1 and are prevented from adhering to the surface of the insulator 3. If the metal aggregated on the outer case 1 remains liquid, it will flow and be discharged from the exhaust hole 4 or the exhaust hole 5.

In the above explanation, metal particles are used as the ionized substance, but the point is that it is sufficient to have a certain amount of metal, and for example, a wire-shaped object may be cut into a certain length and supplied. Furthermore, instead of using an auxiliary electrode to start the discharge, the metal grains at the tip of the electrode 1 may be irradiated with laser light to cause them to evaporate and eject.

Furthermore, if it is difficult to maintain the surface temperature of the outer case 1 and the insulator 3 only by self-heating, a suitable heater may be incorporated or cooling may be performed through a water cooling pipe.

A different embodiment is shown in FIG. The illustrated parts are a means for supplying a low melting point metal and its electrode part, and the other parts are the same as in FIG. 1. A mechanism for supplying a low melting point metal is connected to the main electrode 1, which also serves as an outer case, via an insulator 11. The supply mechanism includes a metal cylinder 12 with a cavity 6 in the center, a piston 7 that moves up and down inside the cavity 6, and an electromagnetic coil 8 that drives the piston 7.
, and a nozzle 9 opened in the middle of the cavity 6. A wire 16 made of a low melting point metal is forced into the cavity 6 through the nozzle 9, driven by the roller 15.

Now, when the piston 7 is pulled upward, the lower end of the piston 7 is placed above the hole of the nozzle 9, so the tip of the wire 16 is pushed out into the cavity 6. next,
When the piston 7 is driven downward, the tip of the wire 16 located within the cavity 6 is cut by the piston 7 and moves downward together with the piston 7. A hole 5 is made in the center of the main electrode J concentrically with the center of the cavity 6, and since this hole diameter is smaller than the diameter of the cavity 6, the cut metal particles 17 do not fall into the discharge vessel. , fit within the space formed by the insulator 11.

When a trigger current is passed between the metal cylinder 12 and the main electrode 1, the metal particles 4 are melted and vaporized, and are ejected from the hole 5 between the main electrodes. At this time, if a sufficient voltage is applied between the main electrodes, a main discharge will occur. The amount of metal particles 4 to be supplied between the main electrodes at each main discharge is determined by the diameter of the wire 2, the diameter of the cavity 6, and the number of reciprocations of the piston 7.

〔Effect of the invention〕

As explained above, according to the present invention, a predetermined amount of the operating substance is separately supplied to the electrode surface, and even if the operating substance is vaporized, the structure is such that the entire amount is ejected between the discharge electrodes. Therefore, stable discharge is possible even with large current discharge.

Furthermore, since the center electrode is wrapped with an insulator, adhesion of ionized substances can be prevented and insulation deterioration can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the structure of a discharge tube of a soft X-ray generator according to the present invention, and FIG. 2 is a longitudinal sectional view showing another mechanism for supplying a low melting point metal. 1.2.12... Electrode, 3, 11... Insulator, 4,
5...exhaust hole, 6,9. ... Pore, 7... Piston, 8... Electromagnetic coil, 10... Metal reservoir, 13.1
4...hole, (忰) trench 1 ni 2 hard

Claims (1)

[Claims] 1. In a device that generates soft X-rays by performing high-speed, large-current discharge during which a pair of electrodes are installed in a vacuum-exhausted container, one electrode is A soft X-ray generator characterized in that a certain amount of low melting point metal is separately supplied to the surface. 2. The soft X-ray generator according to item 1, wherein the low melting point metal is gallium, rubidium, sodium, or a compound containing these. 3. The soft X-ray generator according to item 1, wherein the main discharge is formed by vaporizing the low melting point metal supplied to the surface of the electrode. 4. Item 1, wherein the electrode has a coaxial structure, and the center electrode and the outer cylindrical electrode are separated by an insulator, and the center electrode is wrapped in the insulator. The soft X-ray generator described above.