JPS5839986A - Device for instantly generating strong magnetic field by laser plasma - 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 The present invention relates to
-sient magnetic fields), and more particularly to generating instantaneous strong magnetic fields by laser plasma methods and apparatus.

One field in which generating instantaneous strong magnetic fields as described above would be most useful is in the field of laser-ignited thermonuclear fusion power generation. One proposed technique for generating electricity from controlled thermonuclear fusion reactions involves injecting small pellets of deuterium or tritium into a vacuum chamber.
It involves ``driving'' deuterium ions and tritium ions with energy supplied by laser light to cause a nuclear fusion reaction and generate helium ions and neutrons. Helium ions and neutrons have slightly less mass than deuterium and tritium ions, so the small mass is calculated by the famous Einstein equation [=ic'', where E is the energy generated,
m is the converted mass and C is the speed of light).

When the laser pulse is applied, the outer region of the pellet heats up rapidly and expands outwards at high speed (blown away).
An ionized gas or plasma is formed. The pellet core is compressed by the recoil impact of the outer layer of the pellet being blown away at super high speed, but this is because the rocket is pushed forward by the impact of the rocket jet, and the rifle is pressed against the shoulder by the recoil from firing the rifle. It's the same logic.

According to predictions based on theory, the center of the pellet core will be compressed to a superdensity between 1,000 and 10,000 times the normal solid density, or approximately 10 times the density of the center of the sun (approximately 100 times the density of lead). It turns out. The reason why it is important that the pellet core has the above density is that the probability of collision between active deuterium ions and tritium ions increases significantly. Furthermore, when the density is as above, the unfused deuterium ions and tritium ions absorb the energy of the helium particles before the high-speed helium particles generated by fusion fly out of the pellet core area. Some of it will be absorbed or distributed. This is analogous to fast-moving balls colliding with other balls, imparting their kinetic energy. This kind of energy distribution with the fuel before combustion is what is called the ``bootstrap''.
Trap) ``It causes heating and further increases the reaction rate. Obtaining compression of the core is extremely important in laser fusion.

In reality, there are forces that oppose and prevent core compression. One problem that has only recently been recognized and studied is the effect of active or hot electrons on the plasma in the surface region of the pellet. The generated hot electrons orbit the pellet core at high speed and pass through, heating the core, making it much more difficult to compress the core, and thus reducing the compression for a given laser energy. However, the final energy gain is also reduced. The problems caused by hot electrons and the need to control hot electrons have led to R, B, Spiel++
+an etc., physical Review
1-etters, VOl, 46°No, 13.
p. 821 (March 30, 1981). The measurement of the large return current of the positively charged plasma generated in the laser was reported by R.
physical review 1etters, V
OI.

42, No. 14, 1), 890 (April 2, 1979).

Therefore, one object of the present invention is to control the hot electrons of the laser-generated plasma to reduce the incidence of pellet core damage caused by the hot electrons.

Another object of the present invention is to control high-temperature electrons in plasma generated by a laser by generating an instantaneous strong magnetic field.

Still another object of the present invention is that it is effective in controlling the electrons in the plasma generated by a laser, and is also useful in other fields such as experimental research on the response of biological cells, tissues, etc. to magnetic stimulation. However, it is effective to generate an instantaneous strong magnetic field. - According to the invention, the first plasma generated by the laser is intentionally initiated to generate 114 m of electrons and positive charge plasma. The positively charged plasma is then provided with a low impedance path to the ground, and a strong but very instantaneous magnetic field is generated via the return high current mechanism of the positively charged plasma. In one embodiment of the invention, an object, such as a biological cell, is confined within or near the aforementioned low impedance path and exposed to a momentary strong magnetic field.

In another embodiment of the invention, a fusion pellet is confined within or near said low impedance path and is rake irradiated immediately after the onset of said first plasma and during the duration of a strong magnetic field; The hot electrons of the fusion pellet's plasma are thereby confined in very tight orbits and controlled so that they do not penetrate the core region of the fusion pellet.

An advantage of this invention is that the hot electrons of the laser-generated plasma are controlled by earlier laser-generated events, thus making the laser equipment necessary to generate the fusion plasma It can also be used to generate controlled events of high temperature electrons.

Another advantage of the invention is that momentary strong magnetic fields can be generated for organic and inorganic experimental purposes.

Other objects, advantages and novel features of the invention will become apparent from the following description.

The accompanying drawings show an embodiment of the invention, in which a target 11 is held inside a momentary strong magnetic field generating target assembly 13, and this assembly 13 has one end connected to the ground 1.
5, and the other end is connected to an emitter 17 (see FIG. 1). When placed in a fresh air cavity and irradiated with intense laser light pulses, the emitter 17 is converted into a highly charged positive plasma, and a strong return current flows between the ground 15 and the emitter 17 via the target assembly 13. Become. This exposes the target 11 to an instantaneous strong magnetic field.

A target 1 is provided by a spiral or coiled target assembly 13 as shown in FIG.
1 is exposed to a longitudinal magnetic field. The target assembly 13 can also be formed into a cage shape so that the target 11 is exposed to an azimuthal magnetic field (second
(see figure). In order to generate the desired instantaneous strong magnetic field, it is important to keep the target assembly 13 low impedance and low resistance.

Emitter 17 is preferably a microballoon made of glass, plastic, metal, or a combination of these materials. Emitter 17 is approximately 10 watts/
It is used to generate positive plasma when irradiated with a laser light pulse of d or more. Laser from emitter 17
The hot electrons ejected by the pulse cause a residual positive high potential to cause an instantaneous but strong current to flow through the target assembly 13 to the ground 15 (see Figures 1 and 2). A suitable one is a glass microballoon with a diameter of about 500 microns.

R, F, Benjamin and others, Physica
lReview Letters, Vol, 4
2, No. 14, 9,890 (April 2, 1979), the plasma potential that an irradiated emitter can generate is on the order of 180 kilovolts. , the duration is on the order of nanoseconds. Under the above conditions, instantaneous strong magnetic fields on the order of 100 kilogauss or more can be generated depending on the resistance and reactance of the return current path.

The target 11 is a small object on the order of 1 mm in diameter. The target 11 is an organic substance, an inorganic substance, a metal,
It can be a non-metal, etc. In one application of the invention, target 11 is a fusion fuel-containing pellet.

The pellets are typically sub-millimeter diameter hollow spheres of glass or metal (called microballoons) filled with high-pressure DT glass, often coated with an additional layer or made of metal or plastic. The target 11 is wrapped in a plurality of concentric shells to optimize the interaction with the laser beam of the target 11.

When the present invention is used for laser fusion experiments or power generation, preliminary laser light hits the emitter 17 for a short period of about 1 nanosecond or less before the main laser light hits the target 11.

The resulting "return current" described above creates a strong magnetic field near the target 11 at the moment it is irradiated. This strong magnetic field causes target 1 to
Hot electrons from 1-1 are captured and held in small orbits, preventing them from heating the fuel within Targetera 1-11 and retaining their energy in areas outside the fuel-containing core.

The size and location of target assembly 13 can be as desired. For example, the target assembly 13 may be located outside the absorption region (ie, the volume surrounding the target 11 that absorbs the main laser beam irradiation). When the target assembly 13 is a cylindrical cage (see FIG. 2), free electrons ejected from the target 11 are captured in a small orbit as described above. Alternatively, target assembly 13 may be located between the laser absorption region and target 11 to magnetically shield the fuel in target 11 from hot (or "active") electrons.

Another option is to generate a longitudinal magnetic field, for example by making the target assembly 13 coiled or helical (see FIG. 1).

A person skilled in the art can easily physically construct the inventive device (see FIG. 3). Glass round rod 19 (length approx. 4
c+++, diameter 2+11111 is preferred) at the tip 2
1 and then the tip 21 is ground to a diameter of 125 microns. The large diameter end 23 of the round bar 19 is fixed to the metal base 25 by adhesive or the like, while the tip 21 is similarly glued to the target 11. Note that the target 11 can be a 1 μm aluminum ball or a similarly sized DT fuel pellet.

Target assembly 13, which is a 25.5 micron diameter copper wire, is soldered to metal base 25 and attached to target 11.
It is wrapped around a loli. An emitter 17, preferably a 500 micron glass microballoon, is then glued to the target end 27 of the target assembly 13. Metal base 25 is connected to ground 15 for proper operation.

This invention requires high output laser equipment. Such equipment is available at the Los Alamos National Laboratory.
It is available at many research institutes, institutions, and universities, including the National Laboratory. In order to generate the electromagnetic field necessary to accelerate the electrons to a velocity that can cause the plasma to escape and create a positive potential in the plasma, it is preferable to apply intense laser light of about 1015 watts/d or higher. . Carbon dioxide lasers are preferred because they generate active electrons more efficiently than other commonly available lasers.

The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description, and the invention is not limited to the illustrated embodiments. Those skilled in the art will appreciate that many variations and modifications are possible within the scope of the claims.

[Brief explanation of the drawing]

Figure 1 shows a target surrounded by a coil with one end attached to the emitter and the other end grounded; Figure 2 shows a cylindrical cage with one end attached to the emitter and the other end grounded. indicates a target surrounded by;
FIG. 3 shows an arrangement of coils surrounding a target according to the embodiment of the invention shown in FIG. 11... Target, 13... Target assembly,
15...ground, 17...emitter. Patent applicant United States of America

Claims (1)

[Claims] 1. An instantaneous strong magnetic field generating device for use with a high-power laser, which emits high-temperature electrons and generates positive electric plasma when irradiated with the high-power laser. Emitter means and instant lining! and a grounding means connected to said emitter means and located near said target means to provide a return current path to ground for said positive plasma generated by said emitter means. An apparatus for generating an instantaneous strong magnetic field using laser plasma, characterized in that when the emitter means is irradiated with the high-power laser, an instantaneous strong magnetic field is generated near the target means. 2. The apparatus of claim 1, wherein said return current path provided by said grounding means includes a coiled portion surrounding said target means. 3. The apparatus of claim 1, wherein said return current path provided by said grounding means includes a cylindrical cage-like portion surrounding said target means. 4. The device according to claim 1, wherein the emitter means is a microballoon. 5. The device according to claim 4, wherein the microballoon is a glass microballoon.