JPH0527095A - Cooling method for laser - Google Patents

Abstract

PURPOSE:To generate energy dissipation and carry out the laser cooling free of a theoretical temperature limit, by inducing synchrotron radiation when the pondera motive potential is formed by a plurality of lasers and the charged particles are reflected in reciprocation. CONSTITUTION:The first and second lasers 1 and 2 transmit beams in a z-axis direction, and each pondera motive potential is represented by V1, V2, and the sum is represented by V. Particles 3 are inputted along an x-axis. When the particle 3 enters a laser region, the particle starts to climb the peak of the potential V, and the kinetic energy K reduces accompanied with the ascent, and at the (a) point, K becomes min. The particle 3 descends the billin of the potential V, and at the (b) point, K becomes max. Further, the particle 3 climbs the peak of the potential V, and at the (c) point, the speed becomes zero, and the particle is reflected in the reverse direction. The particle 3 performs synchrotron radiation in the Z direction, and loses the energy K. Accordingly, the particle 3 performs reciprocating movement, and performs synchrotron radiation each time, and the speed becomes as close as zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser cooling method in which charged particles such as electrons, protons and ions are decelerated and cooled by using a laser.

[0002]

2. Description of the Related Art In the conventional laser cooling method, parity V
ol.06 No.01 (1991) As described in P.66 “Cooling of atoms by laser light”, the laser frequency is ω,
When the resonance frequency of the atom is ω ₀ , by setting ω <ω ₀ and irradiating the laser toward the atom, the atom absorbs a photon with energy hω / 2π (h is Planck's constant),
By emitting photons with higher energy hω ₀ / 2π, the atom loses kinetic energy by ΔE = h (ω ₀ −ω) / 2π and is cooled.

[0003]

DISCLOSURE OF THE INVENTION In the above prior art,
In order to cool an atom using a laser, the atom absorbs a photon and then emits a photon, so that the atom is cooled and heated at the same time. Therefore, there is a problem in that the temperature at which these two actions are balanced becomes the lowest temperature that can be reached and a limit value occurs.

Therefore, an object of the present invention is to utilize synchrotron radiation when charged particles are reflected between ponderamotive potentials and reciprocate without utilizing the above-mentioned complicated physical phenomenon. By taking kinetic energy, it is to realize a laser cooling method which is simple in control and equipment and theoretically has no limit to the minimum temperature reached.

[0005]

According to the laser cooling method of the present invention, a plurality of lasers having different electric field intensities are arranged in parallel or non-parallel to form a plurality of ponderamotive potentials, and the propagation of the lasers. A charged particle is incident from a direction perpendicular or non-perpendicular to the direction, the charged particle is reciprocated between the ponderamotive potentials, and further synchrotron radiation is induced to decelerate the charged particle and It is characterized in that it captures between ponderamotive potentials, and is characterized in that a new laser is arranged so as to intersect with the propagation direction of the laser, and it is perpendicular or non-perpendicular to the propagation direction of the laser. Incident the charged particles, and a direction perpendicular to the laser propagation direction and the charged particle incident direction. And wherein the application of a static magnetic field.

[0006]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the injection method of charged particles 3 and the laser arrangement in the laser cooling method of the present invention. Hereinafter, the charged particles 3 are abbreviated as particles 3. Consider the orthogonal coordinate system as shown in FIG. 1, the electric field strength A _1, the frequency omega _1, the laser 1 and the electric field intensity A ₂ is a spot size w _1, the frequency omega _2, laser 2 each z-axis is a spot size w ₂ It is supposed to be propagated in the direction. Here, assuming that the electric field in the lateral direction of the laser (direction perpendicular to the propagation direction of the laser) is linearly polarized in the x direction and its amplitude has a Gaussian distribution in the lateral direction, the amplitude E _{1 of the} laser 1 is The amplitude E _{2 of the} laser 2 is given by the following equation near the x-axis.

E ₁ = A ₁ exp [-x ² / w ₁ ² ], E ₂ = A ₂ ex
p [− (x−x ₀ ) ² / w ₂ ² ] where x ₀ represents the distance between the laser 1 and the laser 2 on the x axis, and A ₁ <A ₂ . Furthermore, ponderosa La Motive potential formed by the laser 1 or the laser 2 is ^{_{V 1 = q 2 E 1 2}} / 4mω
Given by ^{_{1 2, V 2 = q 2}} E 2 2 / 4mω 2 2, their shape on z-x plane is as shown in FIG. here,
q and m represent the charge and the mass of the particle 3, respectively.

Next, in the present embodiment, one particle is considered for simplification, and as an incident method of the particle, an incident method along the x axis on the zx plane as shown in FIG. 1 is considered.
Hereinafter, the behavior or physical mechanism of the particles 3 in the laser cooling method of the present invention will be mainly described with reference to FIGS. 3 and 4. FIG. 3 shows the x of the ponderamotive potential V (V = V ₁ + V ₂ ) formed by two lasers.
It represents the change in that value on the axis. As shown in FIG. 3, the potential V is a maximum value V _1max = q ² A ₁ at x = 0.
² / 4mω ₁ ² , x = x ₀ , maximum value V _2max = q ² A ₂ ² / 4m
take omega ₂ ^2, whereas, it takes the minimum value V _min in ₀ <x <x 0 becomes interval. Further, FIG. 4 shows the change over time in the kinetic energy K of the particles 3. First, at time t = 0, the particle 3 is given an initial velocity v ₀ and is made incident along the x-axis. At this time, the kinetic energy of the particle 3 is given by the following equation.

[0010] ^{_{K = K 0 = γmv 0 2}} /2 where, γ is the Lorentz factor, γ = 1 / (1-
(V / c) ² ) ^1/2 . c is the speed of light. Particles 3 is up to the time t = t ₀ although such speed linear motion without being influenced by the electromagnetic field of the laser, start climbing the mountain time t = t ₀ Thereafter entered the laser region gradually potential V, accordingly Therefore, the kinetic energy K decreases. Time t
= T ₁ , the particle 3 reaches the point a and K has a minimum value.
After that, the particle 3 descends from the mountain of the potential V, and the time t
At t = ₂ , the bottom point b of the potential is reached. At this time, K
Takes a maximum value K ₁ . Further, the particle 3 passes through the mountain of the potential V again and passes through the points i → g → e in this order, and reaches the point c at time t = t ₃ , but its kinetic energy K, that is, the velocity v becomes 0 and the −x direction. Reflected in. At that time, the particle 3 emits synchrotron radiation in the z direction, which is the tangential direction of the orbit, and loses the kinetic energy ΔK corresponding to the energy. After that, the particle 3 is -x
Moving in a straight line in the direction and descending the mountain of potential V e
-> Passes in the order of g-> i point. At time t = t ₄ , the bottom point b of the potential is reached again, and K takes the maximum value K ₂ .
Here, the positions of the particles 3 at the times t = t ₂ and t = t ₄ are the same, but the kinetic energies are not the same. That is, K ₂ is reduced by ΔK with respect to K ₁ , and K ₂ =
The relational expression K ₁ −ΔK holds. After that, after climbing the mountain of potential V again, passing through points h and f,
At time t = t ₅ , the velocity v becomes 0 at the point d and is reflected in the + x direction. What is important here is that the particle 3 should pass through the point a and pass over the mountain of the potential V without being reflected at the point c, but it is equivalent to ΔK due to the synchrotron radiation at the point c. It means that because the kinetic energy was lost, the mountain of the potential V could not be overcome and it was reflected. By repeating the synchrotron radiation in this way, the particle 3 is always reflected at the points e, f, and g at times t = t ₆ , t ₇ , and t ₈ via the point b, and near the point b. Then, it will be stationary at point b. In other words, the particle 3 reciprocates between the potentials and is repeatedly reflected and emits synchrotron radiation, so that the kinetic energy is lost and its velocity approaches to 0 infinitely, and it rests at the bottom of the potential. ..

Now, as described above, the particles 3 are the laser 1
It was possible to get over the mountain of the potential V ₁ by the laser beam, but on the other hand, it could not get over the mountain of the potential V ₂ by the laser beam 2, and it was reflected. Whether or not the particles 3 are reflected by the laser in this way depends on the magnitude comparison between the initial kinetic energy K ₀ of the particles 3 and the maximum value of the potential. That is, in the present embodiment, by setting V _1max <K ₀ <V _2max , the particles 3 can be captured at the bottom of the _{ponderamotive} potential. On the other hand, when V _1max > K _{0, the} particles 3 are reflected by the laser 1 and cannot be captured by the incident method as shown in FIG. Therefore, FIG. 5 (a)
As described above, it is considered that the laser beam is incident from a direction perpendicular to the laser propagation direction, that is, an oblique direction. However, in this case, since the particle 3 also has a velocity component in the z direction, the particle orbit becomes like the orbit 6, and the particle is also reflected and cannot be captured. In order to improve this, by newly disposing the laser 7 so as to intersect the laser 1 and the laser 2 as shown in FIG. 5B, the particle 3 receives the ponderramtive force f9 in the −z direction. It is also decelerated in the z direction, and the particle orbit becomes like an orbit 8 and can be captured at the bottom of the potential. In this way, especially for particles with a small initial kinetic energy in the lateral direction, by newly arranging a laser and injecting it obliquely, the trapping force of the charged particles in the valley of the ponderamotive potential is increased,
The laser cooling method of the present invention is possible.

Further, in the present embodiment, the description has been centered on the deceleration (cooling) of the charged particles by the laser, but on the other hand, the synchrotron radiation emitted when the charged particles are reflected between the potentials is effectively used. Is also possible. For example, it is conceivable to apply a static magnetic field 10 in the y direction in FIG. 5A to further curve the particle orbit and extract the emitted light in the tangential direction. Also, FIG.
It is also possible to extract the emitted light emitted in the ± z direction when the particles are reflected between the potentials and reciprocate as in (b). The intensity of the emitted light can be controlled by the electric field intensity of the laser or the number of incident particles.

Finally, in the present invention, it is best to arrange the lasers so that they are parallel to each other as shown in FIG. 1 and inject the particles from a direction perpendicular to their propagation directions. Further, when a laser is newly arranged at the time of oblique incidence, it is best to arrange it in a direction perpendicular to the propagation direction of the laser.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, multiple lasers may be used rather than a single laser to create the ponderamotive potential V ₁ or V ₂ .

[0015]

According to the laser cooling method of the present invention, unlike the conventional method utilizing the phenomenon of photon absorption or emission of particles, there is an advantage that there is no limit point in the minimum temperature reached by particles. is there.

Further, the particles are reflected between the ponderamotive potentials to be decelerated, and the synchrotron radiation emitted at that time can be extracted and used effectively.
For example, it can be applied not only to the medical field but also to other industrial fields. Furthermore, the intensity and emission direction of the emitted light can be controlled relatively easily.

Furthermore, since the spectrum of particles slowed down by the laser cooling method of the present invention is very sharp without spread due to the Doppler effect or the like, application to atomic clocks can be considered.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a laser arrangement and a particle injection method in the laser cooling method of the present invention.

FIG. 2 xz of ponderamotive potential V
The figure which shows the shape in a plane.

FIG. 3 is a diagram showing changes in the value of the ponderamotive potential V on the x-axis.

FIG. 4 is a diagram showing a change over time in the kinetic energy K of charged particles.

FIG. 5 is a conceptual diagram of an oblique incidence method in the laser cooling method of the present invention.

[Explanation of symbols]

1 Laser 2 Laser 3 Charged Particle 4 Pondelamotive Potential V ₁ 5 Pondelamotive Potential V ₂ 6 Orbit 7 Laser 8 Orbit 9 Pondelamotive Force f 10 Static Magnetic Field

Claims (3)

[Claims] 1. A plurality of lasers having different electric field strengths are arranged in parallel or non-parallel to form a plurality of ponderamotive potentials, and the charged particles are perpendicular or non-perpendicular to the propagation direction of the lasers. Incident,
Laser cooling, characterized in that the charged particles are reciprocated between the ponderamotive potentials, and further synchrotron radiation is induced to decelerate the charged particles to trap them between the ponderamotive potentials. Law. 2. The laser cooling method according to claim 1, wherein a laser is newly arranged so as to intersect with the propagation direction of the laser. 3. A static magnetic field is applied to the charged particles in a direction perpendicular or non-perpendicular to the propagation direction of the laser and perpendicular to the propagation direction of the laser and the incident direction of the charged particles. The laser cooling method according to claim 1, wherein