JP2863446B2 - Storage ring type free electron laser generator with Q switching function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The disclosed technology stabilizes the oscillation frequency and pulse width of light emitted by an insertion light source (wiggler, undulator) provided in a storage ring type free electron laser generator, and its peak output. In the field of technology to increase as much as possible.

[0002]

2. Description of the Related Art As is well known, the prosperity of the industry in recent years is largely based on highly developed science and technology. In particular, research and development of industrial technology based on physics such as electronic engineering and quantum mechanics have been carried out. The burden is extremely large and extends not only to the huge industries such as space-related businesses, but also to the micro world such as the nuclear industry, and to the physical fields such as medicine, chemistry, biotechnology, radioisotope separation and nuclear fusion. In the advanced industries including, there is a remarkable application technology of light and laser.

[0003] Recently, computer-based technology has spread to many industries, and in lithography and the like used for integrated circuits of ICs, etc., which are extremely important as information processing devices, the wavelength of light for forming minute circuits has been increasing. The shorter is the shorter, the more precise patterns are formed, so those that used to use visible light now use ultraviolet light, and recently, X-ray lithography technology using X-rays is also in the development stage. Gas lasers such as a carbon dioxide laser and an iodine laser have also been developed, and their use in various fields has been studied.

On the other hand, laser scalpels and the like have been used for surgical operations in medical treatment, and laser technology has been actively developed for holography and the like, and has high precision, high output, and long stability over time. There is a further need for excellent laser technology that can be used repeatedly in time.

Then, in order to obtain a high output laser beam,
Oscillation is performed using a resonator equipped with a reflection mirror.

[0006] For a laser beam of a constant wavelength, such as a gas laser, free electrons having a predetermined energy are injected into an electron storage ring having an RF cavity, and are accelerated to orbit in an equilibrium orbit thereof. A spontaneous emission light is generated using an insertion light source such as a wiggler or an undulator, and is resonated with electrons via reflection between the resonance mirrors of the resonator to accumulate the light, thereby obtaining a so-called free electron laser (FEL) having a predetermined single wavelength. For example, Japanese Unexamined Patent Application Publication No.
It has been developed as seen in the invention of Japanese Patent Application Laid-Open Publication No. Hei 10 (1999), and various improvements and researches have been conducted for practical use of various applications.

In the storage ring type free electron laser generator, as shown in FIG. 3, an electron beam 2 accelerated by an RF cavity 1 is deflected by a bending magnet or the like (not shown) and orbits on an orbit. The wiggler (undulator) 3 meanders, emits light 4, and the light 4 repeats reflection between the resonance systems 5, 5, resonates with the meandering electrons and oscillates to generate a free electron laser (FEL) 6. Light 4 and electron beam 2 during this time.
The interaction is repeated, and the electron beam 2 is in a heating state (hot) in which the energy spreads widely.
And a narrow cooling state (cold) occurs randomly, and as shown in FIG. 4 (when power is taken in the horizontal direction, the long axis direction, and the time in the height direction), very much like a so-called blocking oscillation in an electric component, The oscillation state occurs randomly, and the peak output is not uniform.
As shown in the figure, not only the power is non-uniform, but also the width is various, and it appears without a constant periodicity.

[0008]

To cope with this, various studies have been made to control the quality of the electron beam, that is, the shift h between the axis of the light 4 and the axis of the electron beam 2 in FIG. And the condition of the temporary oscillation is broken.

During this time, a so-called Q-switching technique has been developed in which the energy spread of the electron beam returns from a hot state to a cold state, or a predetermined control is performed between the two. For example, as shown in FIG. like,
The oscillation of the free electron laser (FEL) 6 is changed by changing the orbit of the electron beam 2 from the solid line state to the dotted line state in FIG. 3 by giving a slight frequency modulation to the high frequency for controlling the RF cavity 1. For example, there is an ACO storage ring type free electron laser generator in France that controls the conditions.
There is a RAS storage ring type free electron laser generator.

Further, a high voltage is applied in a pulsed manner to an electrode provided in a vacuum vessel provided on the orbit of the electron beam 2 to perform Q-switching so that heating (hot) of the electron beam 2 is changed to cooling (cold). Ring type free electron laser generator of the former Soviet Union's VEPP-3 type, which controls the oscillation conditions of the free electron laser (FEL) 6 by controlling the free electron laser (FEL) 6, (Laser generators are not currently used.)
Are known.

In the storage ring type free electron laser generator having the function of performing the Q switching of the conventional mode, a pulse-like deflection force is applied to the circulating electron beam in any case. While the former R
The type in which frequency modulation is applied to the RF control high frequency of the F cavity 1 has a drawback that the response characteristics of the high frequency are poor, high-speed response is not possible, and the rise is not smooth in time, and the repetition frequency can be increased. There was a difficulty that it was difficult.

In the latter type in which a high voltage is applied to an electrode in a vacuum vessel, there is a disadvantage that it is difficult to obtain a high pulse voltage to be applied, and it is necessary to provide the electrode in the vacuum vessel. Therefore, there is a disadvantage in that the entire structure is extremely complicated, and there are disadvantages that not only initial assembly but also maintenance are complicated and the cost is increased as a result.

Of course, means such as changing the reflection mirrors 5 and 5 of the resonance system with respect to the fixed angle can be considered. However, unlike a high-speed rotation mode in ruby laser oscillation or the like, a free electron laser (FEL) device has the Free electron laser (F
There is a bottleneck that such a mechanism does not fit in the state of oscillation of EL) 6.

[0014] Even if many researchers in various countries study the coping technique further, such research is not limited to theoretical analysis, but it is necessary to back up experimental data as described above. Soviet VEP
The P-3 type storage ring type free electron laser generator is not currently in use, and in fact, only two units are in operation in France and Japan. There is a sense of scarcity.

[0015]

It is an object of the invention of the present application to provide a method between the heating (hot) and cooling (cold) of an electron beam by a wiggler (undulator) or the like provided on the orbit of the electron beam based on the above-mentioned prior art. It is a technical issue to solve the problem of oscillation instability based on randomness of the electron beam, and fortunately, the back-up of data by the storage ring type free electron laser generator actually used in operation in Japan and the electron beam By applying pulse control to the magnetic field, the relationship between the heating (hot) and cooling (cold) of the magnetic field can be reliably performed so that the oscillation of the free electron laser (FEL) can be stabilized and the electron in the high-tech industry can be improved. Provision of storage ring type free electron laser generator with excellent Q-switching function that benefits technology application fields One in which cents to.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the construction of the invention of this application, which has the above-mentioned object and the scope of the claims, has been described in order to solve the above-mentioned problems. The electron beam accelerated in the cavity is orbited by an insertion light source such as a wiggler (undulator) on its orbit, and is meandered by the insertion light source of the wiggler (undulator) provided at a predetermined portion, and is generated during the meandering. When the emitted light is reflected by a reflection mirror of a resonance system or the like and resonates with the electron beam to oscillate a free electron laser (FEL), the energy spread of the electron beam causes a difference between heating (hot) and cooling (cold). There is a condition that a transition between the two may potentially cause blocking oscillation, etc., and impair the occurrence of stable oscillation. Orbiting on to conduct a pulse current is interposed a pulse coil to perform the Q-switching action, wiggler (undulator) of insertion devices to in oscillation condition by controlling the pulse width, the period to stabilize the, and,
The technical measures were taken to increase the peak output, stabilize the oscillation output of the free electron laser (FEL), and simplify the Q-switch mechanism, reduce the cost, and maintain it free. is there.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The same parts as those in FIGS. 3 and 4 are described using the same reference numerals.

The embodiment shown in FIG. 1 (schematic representation) is a storage-ring type free-electron laser generator which forms the center of the gist of the present invention, and it is assumed that the basic principle is well known to those skilled in the art. The RF cavity, the bending magnet, and the like are schematically omitted for convenience of illustration, and the electron beam 2 accelerated by the RF cavity (not shown) is formed on a predetermined orbit formed by the bending magnet (not shown). , And meanders in a predetermined manner at a site of a wiggler (undulator) 3 as an insertion light source provided at a predetermined site,
The generated light 4 has reflection mirrors 5 and 5 forming a resonance system.
A free electron laser (FEL) 6 obtained by the oscillation of the electron beam 2 and the resonance light is taken out from the reflection mirror 5 on one side and subjected to a predetermined process.

In the wiggler (undulator) 3 of the insertion light source, the axis 2 'of the circulating electron beam 2 matches the optical axis 4' of the light 4 as shown on the right side of FIG. In the case where the free electron laser (FE)
L) 6 occurs.

However, as described above, the energy spread of the circulating electron beam 2 is such that the heating (hot) state and the cooling (cold) state are potentially randomly generated, and the oscillation output of the free beam laser (FEL) 6 is reduced. It becomes unstable.

To cope with this, in the invention of this application, a pulse magnetic field applying mechanism 7 is interposed on the trajectory of the electron beam 2 as means for giving a Q-switching action, and the pulse coil 7 'is used in this embodiment. Is electrically connected to the pulse current applying device 8 so as to make the current flow in the same direction by making the number of turns (turns) as small as possible in a pair of upper and lower portions substantially horizontally. 9 is made conductive.

The pulse coil 7 is of course used,
The pulse magnetic field applying mechanism such as the pulse current applying device 8 can be designed without difficulty for those skilled in the art at the time of the invention of this application, and can be smoothly constructed, assembled and maintained.

As shown in FIG. 2, the pulse current 9 is oscillated uniformly and with high output power, width, period, and frequency oscillation for a certain period of time, supported by discussion and various experimental data. Designed to be.

When the time during which the electron beam is oscillated as shown in FIG. 2 is extended by the application of the pulse current 9, the heating (hot) state is resumed, and the transition to the cooling (cold) state is repeated. Therefore, the continuous control time is designed optimally.

As a preferred design of the shape of the pulse coil 7 ′, in order to optimally control the orbit of the electron beam, the pulse coil 7 ′ is formed in a rectangular shape in plan view along the orbit of the electron beam 2, and a pulse magnetic field is applied. The Q-switching action of the mechanism 7 indicates that the axis 4 'of the electron beam 2 coincides with the optical axis 4' of the light 4 on the lower right side in the circle shown in FIG. This corresponds to an oscillation state in which the electron beam 2 is concentric.
FIG. 4 schematically shows a cooling (cold) mode which is very slightly shifted by h from the optical axis 4 ′ of FIG.
Heating (hot) state and cooling (cold)
For Q switching between states, the actual design is:
For example, for a radius of 1.2 m of the trajectory of the electron beam 2,
The pulse current 9 is applied by the pulse magnetic field applying mechanism 7 that performs a very small shift h by Q switching action with a length of about 2 to 3 mm for a length of the wiggler (undulator) 3 of about 5 to 6 mm. Is enough.

Of course, the pulse current 9 is 0, that is, the magnetic field is 0.
At this time, the pulse current 9 is adjusted to the orbit of the electron beam 2 so as to satisfy the oscillation condition of the free electron laser (FEL) 6.

Therefore, when the magnetic field is formed, the oscillation condition is deviated from the oscillation condition, and the electron beam 2 changes from the heating (hot) state to the cooling (cold) state during this period.

In this way, a free electron laser (FEL)
6 is a free electron laser (F
EL) 6 is irradiated in a predetermined manner.

Accordingly, the Q-switching has an optimum frequency response characteristic, and the pulse magnetic field mechanism 7 can be of a non-contact type because it is provided outside the vacuum vessel (not shown), so that the structure is simple and the initial assembly is simple. Of course, the maintenance is almost unnecessary and the cost is low, and the Q-switching function is always exhibited in a stable state.

The height of the output power of the pulse shown in FIG. 2 and the width, frequency and period of the pulse current 9 can be desirably designed by design.

Therefore, the oscillation output pulse is extremely stable without the above-described blocking oscillation or the like, and is brought into a desired cooling (cold) state by emitting the electron beam 2 and light, and stable oscillation of the free electron laser (FEL) 6 is desired. Will be obtained.

It should be noted that the embodiments of the invention of this application are not limited to the above-described embodiments. For example, various modes such as providing a pulse coil in a fixed posture crossing the electron beam trajectory are adopted. It is possible.

The installation position is within the scope of selection of design change as appropriate.

The storage-ring type free-electron laser generator to be used is not only for research purposes but also for industrial purposes.

[0036]

As described above, according to the invention of this application, there are basically various uses, and in a free electron laser generator which is widely and effectively used in various industries in the future, light and an electron beam in a resonance system are generated. Unavoidably causes interaction repeatedly, and there is a potential instability factor in which the transition between the heating (hot) state and the cooling (cold) state occurs at random, so the oscillation output of the free electron laser (FEL) In a system where it is preferable to provide a Q-switching function for stabilization, a pulse magnetic field mechanism for providing a Q-switching function is provided, so that the system can be compared with a conventional high-frequency frequency modulation function applied to an RF cavity. A pulse magnetic field with high response characteristics can be applied, the time rise can be smooth, and the frequency can be adjusted as desired. Degree is obtained, made large output power, also, an excellent effect that the width or period can also be a desired are obtained.

In order to form a pulsed magnetic field, a magnetic field can be provided with a coil outside the vacuum vessel. By making it non-contact type, a reverse current is not generated in the electrodes and the like, and handling is easy. There is an excellent effect that the workability and serviceability are good, the safety is high, and the cost can be reduced, not only in the initial assembly but also in various maintenance work.

Further, there is also an effect that the power is charged for the next output even between the pulses, so that the output power of the next pulse can be increased.

Therefore, there is an effect that the intended free electron laser (FEL) oscillation can be stably obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic perspective view including a partially enlarged view of an embodiment of the present invention.

FIG. 2 is a pulse diagram of an oscillation output in a stable oscillation state.

FIG. 3 is a schematic structural perspective view including a partially enlarged view having a Q switching function based on the prior art.

FIG. 4 is an oscillation output pulse diagram in a blocking oscillation state based on the related art.

[Explanation of symbols]

 2 electron beam orbit 3 insertion light source 5 resonance system 7 pulse magnetic field applying mechanism 7 'pulse coil 8 pulse current supply device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Hamada 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Akashi Plant (72) Inventor Tetsuo Yamazaki 1-1-1, Umezono, Tsukuba-shi, Ibaraki Kogyo (72) Inventor: Kazukatsu Yamada, Kazukatsu Yamada 1-1-4, Umezono, Tsukuba, Ibaraki Pref.Instructor, Institute of Technology, Electronic Technology Research Institute, Terukazu Sugiyama (56) Reference: JP-A-3-91286 (JP, A) JP-A-60-124400 (JP, A) Energy and resources VOL. 13 NO. 4 pp. 357-362 (58) Field surveyed (Int. Cl. ⁶ , DB name) H01S 3/30 H01S 3/11 JICST file (JOIS)

Claims (5)

(57) [Claims] 1. A storage ring type free electron laser generator equipped with a resonance system having an insertion light source and a Q-switching function in an electron beam orbit, wherein a pulse magnetic field applying function is interposed in the electron beam orbit. A storage ring type free electron laser generator having a Q switching function. 2. The Q-switching function according to claim 1, wherein said pulse magnetic field applying function comprises a pulse coil attached to an electron beam orbit and a pulse power supply device connected to said pulse coil. Storage electron type free electron laser generator. 3. A storage ring type free electron having a Q-switching function according to claim 2, wherein said pulse coils are arranged in a pair at right and left or up and down along an electron beam trajectory. Laser generator. 4. A storage ring type free electron laser generator having a Q switching function according to claim 3, wherein said pulse coils are formed so that currents flow in the same direction. 5. A storage ring type free electron laser generator having a Q switching function according to claim 3, wherein each of said pulse coils is formed in a rectangular shape along an electron beam trajectory. .