JPS59500935A - Split type plasma excitation recombination light source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Split type plasma excitation recombination light source Background of the invention The present invention relates to plasma excited recombination light sources such as lasers.

Applied Physics Letters, No. 3 Vol. 6, No. 8, p. 615 (1980). W, TSilfvast), L, H, 5zet o) and O. R. Wood, Jr. (0, R, Wood, II), generates a large number of metal vapor sources through the split plasma and recombination (SPER) mechanism. New electrical discharge device developed to generate laser operation in chair vectors It talks about the This laser has a small gap between each row of adjacent stripes. Leaving no gaps: A large number of (laser material) placed edge-to-edge on an insulating substrate. Contains a number of narrow metal stripes. Striped - buffer dregs (preferred) or true placed in a laser cavity containing the sky, typically 1 m thick - 2 m rtun wide length in m], Otnm. (Hereafter referred to as "bulk electrode").High voltage.

When a high current pulse is applied to the edge stripe of this configuration, the dense metal ion A lasma is formed in each gap.

Once formed, these plastics (essentially consisting of vaporized stripes of material) Zuma spreads out in a hemispherical shape and is a backlog gas (e.g. helium) at low pressure. cooled and recombined in the presence of Using this laser configuration, the laser operation i- 1: ], ] elements (Ag, Bi, C, Ca, Cu, In, M9゜Pb , Sn-, Zn, ), 70 or more of 029 to 3.95 tlm It was observed at near-infrared wavelengths. Three of them (A9゜Zn, In) have a neutral spectrum. No vibration was observed in the sample.

Some of these are reported in the APL literature mentioned above. , and others, Tafuru T Shilfheaist (W, T, 5ilfva Appliecl Physics Letter by St. ters), Volume 39, No. 3.

2] On page 2 (t-98], ), Volume 7, No. 1, page 34 (1,982).

5PER lasers are simple to construct, easily dimensioned in length and volume, and have a long lifespan. It has been shown that it can provide high efficiency, and it also has the potential for high efficiency. It is US Patent No. No. 4,336,506.

The laser operation in a 5PER laser is, for example, a relatively high-pressure Huckland cylinder. Even under conditions that normally promote plasma formation, such as The same observation cannot be made with metals. Performing laser operation in metal vapor A figure of merit M that defines the relative ease of can be introduced. M is as follows It is defined as follows.

M=(K(1)T21-' (1) Here, K (li gold metal thermal conductivity, C is the specific heat of the metal, P is the density of the metal, T is the metal This is the feed temperature of the electrode surface. This expression shows that due to ions or current passing through the electrode surface, It is derived from the thermal equation for the time required to raise the electrode surface temperature to a value T.

The vapor pressure of metal is about 0.1. In the case of Cd metal at a temperature of Torr- The table below lists a number of metals along with the calculated value of M.

For alkali metals (Na, Li, (:a)), M is for these metals It should be calculated for the oxide formed. Experimentally, d, M~1 metals are compared At a relatively low background gas pressure (for example, 1-10Tθrr), the shift of 5 Contains the split metal vapor plasma necessary to generate laser action in a PER laser. On the other hand, metals such as Li, At, Ca and Cu was found not to produce a split plasma. With these metals, As the hack crack pressure decreases, the hack crack pressure between non-adjacent electrodes decreases. A discharge current is carried by the discharge in the gas, effectively eliminating the metal vapor arc that occurs during the process. , reducing the number of metal vapor plasmas and thus lowering the net gain.

Summary of the invention The metal stripes constitute the electrodes, and they are sufficiently thinner than prior art bulk electrodes ( Typical cases are approximately 10 minutes, so that discharge occurs only between adjacent electrodes. This eliminates the problem of short circuits associated with bulk electrodes, and allows the use of materials with M<<1. The metal N’? Even at relatively low hack ground gas pressures, separation is difficult. Split metal vapor plasma discharge and laser operation can be obtained in a 5PER device I found out. Using this thin electrode SPE'R structure, four types of metals (Li, , Achieving laser operation in Ae, Ca and Cu). Among them, Ba Laser oscillation was not possible using low voltage electrodes and low pressure. In addition, the N1 electrode A segmented gas plasma discharge in the 5PER used was observed.

Brief description of the drawing FIG. 1 is a schematic configuration diagram of a 5PE laser according to an embodiment of the present invention; Figure 2 shows 1. , = 133μ 1 transition and 537. in Cd 1.1. For a Cd5PER laser operating at 8 nm transition ζ), as a function of helium pressure Figure 17 shows the relative output power of Figure 3 shows a single-gap AIS PER device operating at a helium pressure of 3 Torr. 394.4 nm A/r resonance line from vice, 28], 6 nm AA' 1. I line and 569. nm Ae as a function of gap width for IIT line A graph of the relative intensity of natural radiation, Figure 4 shows three types of electrolytic thickness: J, 2 Tnm, 0.5 mm, 0, 1 In 11 gap A45PER laser as a function of gap width for 25 mm. I recently started graphing helium pressure, which operates reliably. FIG. 5 is a schematic diagram of another embodiment of the invention using bimetallic stripes.

a) An embodiment of the invention used to generate a laser is shown in FIG. There is. According to the present invention, the plurality of metal stripes 101-110 each have a Especially thin electrodes.

electrically isolated so as to configure the stripes and leave a small gap between each pair of adjacent stripes. They are placed end to end on a marginal plate 120. This electrode configuration is It is installed in the cassette 125. The capacitor 30 and the switch 132 are connected to the first It is connected in series between the electrode 101 and the last electrode Φ110. Capacity 130 is a number Charged to ten kilovolts and discharged across a lucky metal strip with a spark gap be done. However, operation at much lower voltages (e.g. tens of volts) is also possible. Ru. The resulting current pulse creates a bright metal vapor plasma in each gap.

Regions 141-149 in Figure 1 extend outward from the gap into the background dust. This shows the shape of the plasma after it has expanded into a hemispherical shape.

It is not necessary that each stripe be entirely composed of material that can be vaporized into the plasma. No. As shown in Figure 5, if the cathode ends 202b, 203b, etc. It is made of metal, and the anode ends 202a, 203a, etc. meet the operating conditions of the device. It is sufficient if the bottom is made of non-volatile material. For example, in this example , each stripe is compatible with non-volatile vertical elements (e.g. 202a and 202b). Consisting of volatile materials electrically connected to each other. In the field of view intended here, non-volatile An example of a flexible material is tungsten.

Furthermore, stripes of different volatile materials within a single device to yield a polychromatic source can be mixed.

To construct a resonator for laser radiation, the reflection should be maximized at the desired laser wavelength. The two dielectric spherical mirrors 150 and 151 are coated to increase the size. for example , these mirrors are mounted on the ends of the tubes that make up the cassette 125. This joint The optical axis 160 of the vibrator is parallel to the row of foil electrodes and located slightly to the left.

The output from this resonator is passed through a suitable filter, as shown by line 170. A suitable photodetector (not shown)--L is focused.

C(I S P E R1 In the conventional technology of NOSA, the capacity is 1301i 0. 01μF”, charged to 21KV, 12MF:Tz A current pulse of 8/I OA with a repeating frequency was uttered. hackgran The docus was helium at a low pressure of 5 Torr. Does the mirror have a radius of curvature? A laser with an optical axis located at 37?7,''/?1'11i pole-hi7 mIn. For radiation, a resonator with a length of 12 tyn was formed.The photodetector was placed at room temperature ( It was a Gc diode.

example Using the configuration of the type shown in FIG. 1, four rows of metal elements L1. At , I: between 569.6 nm and 54601′1m in a and C11 S)) ER lasers were created at visible and near-infrared wavelengths. Table 1 is observed Wavelengths and identification of transitions for these elements are shown.

In the experimental configuration of Konera's SP E R laser, ]-J OTorr's ( Hackkland gas of helium was used at Iy pressure. 41 flying lights on a glass board The poles were arranged vertically.

The electrodes were typically 25 cm long, 25 cm wide, and 0.1-02 cm thick. adjacent The gap between the electrodes is approximately 0.2 mm for Li and (a), and approximately 0.2 mm for At and Cu. In this case, about 0.5 mm was suitable. The important thing is that this thin electrode shape has a , used in previous experiments using 0 body bulk electrodes separated by 10 to 2.0 mm. This is different from Excite this 4] electrode configuration with a 15-30 KV pulse and When a current pulse of 5/l5eC is formed at O-20OA, metal vapor is generated in each gap. A plasma was formed. 40 metal vapor plasma is discharged from the interstitial region by low pressure helium gas. It expanded to 20-25 on during the current (1-1,0 Torr), and after the claw discharge, the impact Cooled to the point where sudden recombination begins to dominate all other electron loss processes. It will be done. Collisional deexcitation of a highly excited state of a recombining ion or atom indicates that the radiative decay is the collisional decay ``Give a level of density that will control the population and achieve population growth.'' Ru.

In these plasmas, 1], a 5 m long laser cavity is placed on a foil electrode of 7 brains. When placed parallel to this, laser action was observed. Curvature) 4'-diameter 2m A resonator formed by two highly reflective dielectric coated mirrors 150 and 151 is It is used in lasers with wavelengths shorter than 1900 nm, and consists of two gold-coated mirrors with a radius of curvature of 2 m. Formed by mirror (one mirror has a connecting window with a diameter of 2 mm on medium heat) The developed resonator was used for wavelengths of 11-900a and above. Laser output Through a 1/4 meter spectrometer, a photomultiplier (depending on the wavelength), Kermanium detector or C1 cooled by liquid helium Ge:Cu detector used was detected.

Thirty new recombinant lasers made using the electrode 5PER structure according to the present invention It is shown in Table 1. Does recombination, the ionization step, always occur in descending order? Therefore, the temporary behavior of the laser output depends on the specific neutrality or impurities involved in the laser operation. Helps identify the on-stage. Recombinant lasers typically Since it occurs beyond the forbidden band in the spectrum, it is also difficult to identify what is included in a particular stage. It wasn't difficult.

Recombinant laser operation In order to improve recombinant laser operation, especially in the high ion stage, plasma The plasma should be divided as shown in Figure 1 to maximize cooling [the plasma should be divided as shown in Figure 2]. As shown in Figure 2, the gain is maximum at low pressure (for example, a helicopter). um).

For techniques to increase gain through plasma splitting, see 5ilfvas cited above. In a properly operating 5PER laser as described in the ts papers and patents, As a result, a metal vapor arc is formed in each gap after gas breakdown. But first As mentioned above, in the case of metals with a small figure of merit M, as the helium pressure decreases, the release Electrical current is carried by discharges in helium sludge between non-adjacent electrodes, alternating Effectively shorts out multiple vapor arcs, reducing the number of metal vapor plasmas and thus increasing positive Go down the taste laser gain. The time delay in the final path formation of the arc discharge and each path depends on the growth rate of ionization along the path. Because the applied voltage is Breakdown occurs not only in the gaps in the buffer scum between the bulk electrodes but also along the path. This is because the voltage exceeds the voltage required to cause . Ions between adjacent strong bulk electrodes The progress of ionization is controlled by the ionization phenomenon in the hack ground gas, and It is approximately constant for both electrode shape and electrode shape. On the other hand, the metal vapor in the interstitial region Techniques that enhance growth should promote ionization growth and vapor production, and therefore It is thought that this is largely determined by the characteristics of the specific metal used as the electrode. .

It is believed that hackground cus serves a dual purpose in the plasma expansion process. It is being (1) Cool the electrons, thereby introducing electron-ion recombination.

(2) Confining the inversion region to the moat volume of the optical cavity. arises from the recombination of Cd S in monovalent ions (Ccl 1+) resulting from recombination of neutral atoms and Cd A typical laser power versus pressure curve for an R type device is shown in Figure 2. is shown.

For excitation, low Huckland gas pressures are found to be important for high ionic stages. .

For recombinant laser operation, the gap width is optimized depending on the spontaneous radiation intensity from the metal vapor arc. You should choose to do so.

Foil electrode AI S P E R 394.4 nm, /+7' T resonance in laser The increasing gap width dependence of the spontaneous radiation intensity of the line is shown in FIG. Al　l+ and The line of radiation intensity in the spectrum for Al changes with the gap in approximately the same way. I also understood. When the gap width increases beyond 2.0 mm, the emission from metal vapor The radiation decreased and a helium discharge appeared between the metal vapor and a mainly hemispherical plasma. No. The results shown in Figure 3 indicate that (if the electron density is not high) the intensity of spontaneous emission will be It increases with the gap width, and the electrode AI S P E R de It has the maximum value in the device.

Effect of gap width and electrode thickness on plasma formation at relatively low pressures was tested as follows.

In order to obtain a macroscopically uniform gap, a large number of 1 1-gap thin electrode At-S P E R device (each with a different gap width) ) was produced [2. Gradually reduce the pressure of the helium hack and This is due to the formation of helium plasma between electrodes that are not in contact, or due to the presence of multiple gaps. "Short-circuited": <There is a specified pressure. This pressure is The lowest pressure that produces a type plasma is marked Pm]n. 200A peak with different electrode gap widths and electrode thicknesses when excited with a current and a duration of 5 μsec. The results of measuring Pm1n for a series of devices are shown in FIG.

In contrast to the strong dependence on electrode thickness, changes in electrode width have little effect. I found out. In the case of a gap width of 0.1 mm or more, the thinnest electrode 4@(0,1 25 mm) produced low values of Pm1n and a segmented Al vapor plasma. . Therefore, the actual gap width used will depend on the minimum pressure required for ray → no action. However, it is possible to maximize the net gain and minimize the probability that recombinant lasing occurs in the In order to increase the It is.

The configurations described above are merely illustrative of the many possible embodiments that may be implemented using the principles of the present invention. It should be understood that the

Thin electrodes reduce heat loss by conduction into the electrode, which is more likely to occur at the electrode surface. They work well because they accelerate thermal processes. For bulk electrodes, The heat flow into the electrode is three-dimensional, but in thin shapes the heat flow is almost two-dimensional. It is. Therefore, heat loss due to conduction (d is smaller for thin geometries, and thinner electrodes reaches a given temperature in a shorter time. This effect results in a higher vapor pressure This is thought to increase the ionization growth rate.

However, regardless of the mechanism, the split type plasma high Not only does it allow the use of low figure of merit metals in the Plasma generation becomes possible in reactive metals (e.g. alkali metals) that disrupt .

In addition, the thin electrode SPR device of the present invention can be applied to Ni (M2003). We were able to observe that spontaneous radiation occurs due to the wavelength characteristics of visible radiation.

b list 1 FIG. 2 5 (3 Grain width 1mm1 M8 width (open) international search report

Claims (1)

[Claims] J At least two stripes (101 -110) and means for applying electrical pulses to said at least two stripes. Consisting of (130, 132), At least a portion (202b) of the at least two stripes is When a target pulse is applied, it is converted to generate plasma, and the plasma (wastely cooled) In a recombining light source that recombines to produce radiation, the fraction is much smaller than 1 made of a metal having a figure of merit M, wherein the discharge path is connected to the at least two stripes. recombination light characterized by being sufficiently thin so that it occurs only between one adjacent source. 2. In the light source according to claim 1, the performance of the material M≦033 A light source whose q1 characteristic is that it has an index. 3. In the light source according to claim 2, the material is Li, At, It is characterized by being a metal selected from the group consisting of Ca, Ni and Cu. light source. 4. The light source according to claim 1, wherein the at least two struts The light source is characterized in that the thickness of each layer is about 01-0.2 mm. 5. In the light source according to claim 1, a pressure of about 1-10 Torr is used. the at least two stripes including a gas container containing helium; A light source characterized in that it is placed within a gas container. 6. In the light source according to claim 1, the at least one gap is , a width of about 0.2-0.5 mm. 7. In the light source according to claim 1, the at least two struts 1. A light source characterized in that each of the tubes consists entirely of the material. 8 In the light source described in claim 1.2.4.5.6 or 7, Used as a laser, further comprising a laser resonant cavity suitable for emitting said radiation therefrom; characterized in that said excitation means are suitable for producing said radiation in said cavity; A light source used as a sign. 9. In the light source according to claim 8, the interest rate is Li, Al, A patent characterized in that Ca and Cu are selected from the group consisting of