JPH03254164A - X-ray preionized laser unit - Google Patents

Abstract

PURPOSE:To enhance reliability of an X-ray transmitting metal film electrode and to lengthen service life by arranging an X-ray generating target, independently from one of main discharge electrodes or the X-ray transmitting metal film electrode, in a low pressure chamber. CONSTITUTION:Ions, produced through discharge in the proximity of an ionization wire anode 9, are attracted to a grid electrode 11 and impinge against an acceleration cathode 13 thus producing secondary electrons. The secondary electrons are then accelerated between the acceleration cathode 13 and the grid electrode 11 and impinge against the inclined face of an X-ray generating target 7 thus generating X-ray. Thus generated X-ray then passes through an X-ray transmitting metal film electrode 1 and irradiates the interior of a main discharge chamber 15, and a laser medium is excited by a high voltage applied between a main discharge electrode 17 and the X-ray transmitting metal film electrode 1 thus causing oscillation. When the X-ray generating target 7 is arranged independently from one main discharge electrode or the X-ray transmitting metal film electrode 1, in a low pressure chamber 3 both thermal load and mechanical load of the X-ray transmitting metal film electrode 1 are relieved, resulting in the improvement of reliability and lengthening of service life.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) This invention is an excimer laser, TEACO2.

The present invention relates to a pulsed laser such as a metal vapor laser that excites a laser medium by pulsed glow discharge to generate laser oscillation.

(Prior Art) There are various types of pulsed laser discharges that are excited by pulsed glow discharge to produce laser oscillation, such as excimer lasers, TEACO2, and metal vapor lasers. Common problems with these lasers include deterioration of the laser medium due to metal vapor contamination generated from arc discharge in the spark gap used for pre-ionization, and spatial non-uniformity of pre-ionization due to ultraviolet rays from arc discharge. be.

As a result, the current challenges are to extend the lifespan of laser equipment, increase output power, and increase repetition rate.
For this reason, the X-ray preionization method is being adopted.

FIG. 3 shows a schematic diagram of the configuration of a conventional X-ray preionization method.

A low pressure chamber 53 is provided behind the X-ray transparent membrane metal electrode 51, and generally helium gas is in the range of several mTorr to several tens of mTorr.
mTorr is enclosed.

An ionizing wire anode 55 is arranged in the low pressure chamber 53 almost parallel to the laser beam.

Further, a grid electrode 57 is placed at the same potential as the X-ray transparent membrane metal electrode 51, and an accelerating cathode 59 is provided facing the grid electrode 57.

In the X-ray generator configured as described above, the ionizing power source 61 is connected to the ionizing wire anode 55 using the switch 63.
A voltage is applied to generate a discharge near the ionizing wire anode 55, and at the same time as the discharge occurs, an accelerating voltage is applied to the five accelerating cathodes by the switch 67 of the accelerating power source 65.

As a result, ions generated by the discharge are transferred to the grid electrode 5.
7, only the ions collide with the surface of the acceleration cathode 59 to generate secondary electrons.

These secondary electrons are accelerated between the grid electrode 57 and
The X-rays collide with the radiation-transmissive film metal electrode 51 and irradiate the main discharge chamber 69 with the X-rays.

As a result, the electric charge previously stored in the capacitor 71 is transferred to the capacitor 73, and a high voltage is applied between the main discharge electrode 75 and the X-ray transparent film metal electrode 51 to excite the laser medium and cause oscillation.

In a conventional laser device with such a configuration, originally.

Since the pressure inside the main discharge chamber 69 is as high as 10 atmospheres from the diffused pressure, a large mechanical load acts on the X-ray transparent membrane metal electrode 51. Moreover, the X-ray transparent film metal electrode 51 has a large thermal load because it functions as an X-ray generation target that generates X-rays and as a main discharge electrode that excites and oscillates the laser medium. This may cause strain in the metal electrode of the permeable membrane, which may even lead to membrane destruction, which may have a significant negative impact on the entire device.

(Problems to be Solved by the Invention) As described above, in order to put an X-ray pre-ionization type laser device into practical use, in the conventional technology, a large mechanical load acts on the X-ray transparent membrane metal electrode 51, and Since it serves both as a generation target and a main discharge electrode, it has the drawbacks of low reliability and short life.

An object of the present invention is to solve the above problems and provide a laser device with high reliability and long life.

[Structure of the Invention] (Means for Solving the Problems) The structure of the present invention for solving the above problems consists of a pair of main discharge electrodes arranged opposite to each other, and at least one of the main discharge electrodes has an In an X-ray pre-ionization laser device configured with a radiation-transmitting membrane metal electrode, a low pressure chamber is provided which is separated by the main discharge electrode and the X-ray transmission membrane metal electrode, and the X-ray transmission An X-ray generating target having the same potential as the X-ray transparent membrane metal electrode is placed behind the membrane metal electrode, and the surface of the X-ray generating target is formed to be inclined with respect to the surface of the X-ray transparent membrane metal electrode. a grid electrode having the same potential or a negative potential as the X-ray transparent membrane metal electrode is arranged opposite to the inclined surface of the X-ray generation target, and an accelerating cathode is arranged behind the grid electrode, The present invention is characterized in that an ionizing wire electrode is disposed substantially parallel to the optical axis of the laser between the inclined surface of the X-ray generation target and the grid electrode.

Furthermore, at least a portion of the acceleration cathode is made of a material with a low work function.

(Function) Ions due to the discharge generated near the ionizing wire anode are attracted to the grid electrode, and the ions collide with the accelerating cathode to generate secondary electrons.

These secondary electrons are accelerated between the accelerating cathode and the grid electrode, collide with the inclined surface of the X-ray generating target, and generate X-rays.

The generated X-rays pass through the X-ray transparent membrane metal electrode and are irradiated into the main discharge chamber, and the laser medium is excited by the high voltage applied between the main discharge electrode and the X-ray transparent membrane metal electrode, causing oscillation. be exposed.

In this way, in order to generate X-rays, the target for X-ray generation was provided in the low-pressure chamber separately from the X-ray transparent membrane metal electrode, which is one of the main discharge electrodes. Both the thermal load and the mechanical load on the electrode are reduced, improving its reliability and extending its life.

At least a portion of the accelerating cathode is made of a material with a low work function, so secondary electrons are sufficiently emitted due to ion collisions, increasing the amount of X-rays generated and providing stable oscillation. .

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of the configuration of the X-ray preionization method of the present invention.

A low pressure chamber 3 is provided behind the X-ray transparent membrane metal electrode 1,
Helium gas ranges from several mTorr to several tens of mTorr
It is enclosed.

An X-ray generating target 7 having an inclined surface 5 having an inclination angle of, for example, 450 with respect to the surface of the X-ray transparent membrane metal electrode 1 is installed in the low pressure chamber 3, and this X-ray generating target 7 It is arranged at the same potential as the permeable membrane metal electrode 1. The target 7 is made of nickel, gold, or the like. An ionizing wire anode 9 is disposed substantially parallel to the optical axis of the laser, facing the inclined surface 5, and behind the ionizing wire anode 9, the X
A grid electrode 11 having the same potential as the line-transmissive membrane metal electrode 1 is arranged, and an accelerating cathode 13 is provided behind the grid electrode 11.

A main discharge chamber 15 is provided adjacent to the low pressure chamber 3, and one main discharge electrode 17 facing the X-ray transparent membrane metal electrode 1 is provided within the main discharge chamber 15. , constitutes the other main discharge electrode.

In the X-ray generator configured as above, the switch 23 is closed and the voltage of the ionizing power source 25 is applied to the ionizing wire anode 9 to generate a discharge near the ionizing wire anode 9,
After 0.1 to 1 microseconds, the switch 27 is closed to apply negative accelerating voltages from the two accelerating power supplies to the accelerating cathode 13.

As a result, ions generated by the discharge are transferred to the grid electrode 1.
1, only the ions collide with the surface of the acceleration cathode 13 to generate secondary electrons.

These secondary electrons are accelerated between the acceleration cathode 13 and the grid electrode 11, collide with the inclined surface 5 of the X-ray generation target 7, and generate X-rays.

As a result, the X-rays pass through the X-ray transparent membrane metal electrode 1 and are irradiated into the main discharge chamber 15 .

One switch is closed, and the electricity previously stored in the capacitor 21 is transferred to the capacitor 31, and the main discharge electrode 1 is transferred to the capacitor 31.
A high voltage is applied between the laser beam 7 and the X-ray transparent membrane metal electrode 1 to excite the laser medium and oscillate, and a beam is generated perpendicular to the plane of the paper of FIG.

Furthermore, the same result can be obtained by applying a negative DC voltage to the acceleration cathode 13 in addition to applying a negative pulse voltage as described above.

As described above, since the X-ray generation target 7 is provided in the low pressure chamber separately from the X-ray transparent membrane metal electrode 1, which is the main discharge electrode, the heat load on the X-ray transparent membrane metal electrode 1 is This reduces mechanical load, reduces thermal strain, and extends life. Furthermore, the X-ray generating target 7 can be formed into a block shape, which also improves the strength.

The secondary electrons emitted from the acceleration cathode 13 collide with the inclined surface 5 of the X-ray generation target 7 and emit X-rays, but because of the inclined surface 5, the direction of incidence of the secondary electrons is X-rays are emitted in a substantially perpendicular direction, and the emitted X-rays can reach the X-ray transparent membrane metal electrode 1 and the main discharge electrode 17 in the forward direction of the emission direction.

FIG. 2 shows a longitudinal cross-sectional view of an X-ray generating target 37 according to a second embodiment.

The inclined surface 35 of the X-ray generating target 37 has a shape that allows X-rays generated by secondary electrons from the accelerating cathode 13 to reach the X-ray transparent membrane metal electrode 1 and the main discharge electrode 17, for example. It is formed by a parabolic curved surface.

The inclined surface of the X-ray generating target may have various shapes other than those described above without departing from the effects of the present invention.

In addition, in order to sufficiently generate secondary electrons through ion collisions at the acceleration cathode 13, the base material of the acceleration cathode 13 is made of a common electrode material such as inexpensive stainless steel, brass alloy, or aluminum alloy. It is desirable to use a material with as low a work function as possible for at least a portion 1 of the acceleration cathode 13, such as its surface.

If a material with a low work function, such as barium oxide, titanium carbide, or lanthanum molybdenum hexaporide used for the emitter material, is used, the effect of emitting secondary electrons will be further improved.

Various methods can be used to attach the surface material to the base material portion of the acceleration cathode 13, such as surface coating, vapor deposition, fixing of a thin plate, and coating of barium oxide.

In FIG. 1 and s2, the reference numeral 33 is an insulating material.

[Effects of the Invention] As described above, the X-ray preionization laser device of the present invention
The X-ray generation target for generating rays was installed in the low-pressure chamber separately from the X-ray transparent membrane metal electrode, which is one of the main discharge electrodes. Both loads are reduced and strain is reduced, making it possible to realize a laser device with higher reliability and longer life than conventional devices when putting the X-ray pre-ionization laser device into practical use.

When at least a portion of the accelerating cathode is made of a material with a low work function, secondary electrons are sufficiently emitted due to ion collisions, the amount of X-rays generated increases, and stable oscillation is performed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an X-ray preionization laser device according to a first embodiment of the present invention, viewed from the beam direction. FIG. 2 is a cross-sectional view of a main part showing a second embodiment, and FIG. 3 is a schematic structural diagram including a cross-section of a main part of a conventional X-ray preionization laser device. 1... X-ray transparent membrane metal electrode 3... Low pressure chamber 5...
・Slanted surface 7.37... Target for X-ray generation 9... Wire anode for ionization 11... Grid electrode 13... Cathode for acceleration 17... Main discharge electrode, private patent attorney Hidekazu Miyoshi Figure 1 Figure 2

Claims (2)

[Claims] (1) In an X-ray pre-ionization laser device comprising a pair of main discharge electrodes arranged opposite to each other, and at least one electrode of the main discharge electrodes is constituted by an X-ray transparent film metal electrode, the main discharge electrode and the A low pressure chamber isolated from the X-ray transparent membrane metal electrode is provided, and an X-ray generation target having the same potential as the X-ray transparent membrane metal electrode is placed behind the X-ray transparent membrane metal electrode in the low pressure chamber. The surface of the X-ray generating target is formed to be inclined with respect to the surface of the X-ray transparent film metal electrode, and the surface of the X-ray transparent film metal is formed opposite to the inclined surface of the X-ray generating target. A grid electrode having the same potential or a negative potential as the electrode is arranged, an acceleration cathode is arranged behind the grid electrode, and the optical axis of the laser is arranged between the inclined surface of the X-ray generation target and the grid electrode. An X-ray pre-ionization laser device characterized in that an ionization wire anode is arranged substantially parallel to the ionization wire anode. (2) An X-ray preionization laser device, wherein at least a portion of the acceleration cathode is made of a material with a low work function.