KR20200110051A - Apparatus and method for generating free electron laser - Google Patents

Abstract

Disclosed are a free-electron laser generation apparatus applicable to a photolithographic process and a free-electron laser generation method thereof. According to the present invention, the free-electron laser generation apparatus comprises: an injector scanning an electron beam; a linear accelerator receiving the electron beam passing through the injector and using an electromagnetic field to accelerate or decelerate electrons; a first path changing unit changing a moving path of the electron beam passing through the linear accelerator; a bunch compressor longitudinally compressing an electron bunch included in the electron beam passing through the first path changing unit; an undulator generating a free-electron laser by an interaction between the electromagnetic field and the electron beam passing through the bunch compressor; and a second path changing unit changing a moving path of the electron beam passing through the undulator to input the electron beam to the linear accelerator.

Description

A device and method for generating a free electron laser {APPARATUS AND METHOD FOR GENERATING FREE ELECTRON LASER}

The present disclosure discloses an apparatus and method for generating a free electron laser.

The contents described in this section merely provide background information on the embodiments disclosed in the present disclosure, and do not constitute prior art.

The photolithography process refers to a microfabrication process for patterning a wafer or the like. The photolithography process is an essential process for semiconductor manufacturing, and the accuracy and speed of the photolithography process can be related to the quality and speed of semiconductor production.

In the conventional photolithography process, I-line, krypton fluoride laser (248 nm), argon fluoride lasers, laser produced plasma (LPP, 13.5 nm), and the like have been used. However, the above-described light sources provide limited power of less than 1kW and have problems of ionization contamination and high cost.

Therefore, there is a need for technologies that can replace conventional light sources in a photolithography process.

According to at least one embodiment, an apparatus and method for generating a free electron laser applicable to a photolithography process is provided.

According to one aspect, an apparatus for generating a free electron laser is disclosed. The free electron laser generator includes: an injector for scanning an electron beam; A linear accelerator to which an electron beam passing through the injector is incident, and accelerating or decelerating electrons using an electromagnetic field; A first path changing unit for changing a traveling path of the electron beam passing through the linear accelerator; A bunch compressor for compressing electron bunches included in the electron beam passing through the first path change unit in a longitudinal direction; An undulator for generating a free electron laser by the interaction of an electromagnetic field and an electron beam passing through the bunch compressor; And a second path changing unit for changing a traveling path of the electron beam passing through the undulator and entering the linear accelerator.

The free electron laser generator includes a bunch decompressor that is provided between the second path changing unit and the undulator and expands a bundle of electrons included in the electron beam passing through the undulator in a longitudinal direction. It may contain more.

The free electron laser generating device is provided between the linear accelerator and the first path changing unit, and among the electron beams passing through the linear accelerator, a high energy electron beam is incident on the first path changing unit, and the low energy electron beam is It may further include a dump section for dumping.

The dump section includes a plurality of bending magnets, and at least one of the plurality of bending magnets may bend the high energy electron beam and the low energy electron beam at different angles.

The free electron laser generating apparatus may further include a merging unit for changing the path of the electron beam scanned by the injector to be incident on the linear accelerator.

The merging unit may include a plurality of quadrupole magnets and a plurality of bending magnets.

The linear accelerator may recover kinetic energy by accelerating the low energy electron beam scanned from the injector and decelerating the high energy electron beam passing through the second path changing unit.

The linear accelerator may increase or decrease the energy value of the electron beam passing through the linear accelerator by changing the energy of the electron beam passing through the linear accelerator.

The linear accelerator may include a plurality of cells having the same structure.

Each of the first path change unit and the second path change unit includes a plurality of cells and may have a mirror symmetric structure.

Each of the plurality of cells may include a TBA (Triple Bend Achromat) portion including a plurality of bending magnets and a plurality of quadrupole magnets, and a plurality of quadrupole magnets symmetrically arranged on both sides of the TBA portion.

The bunch compressor may include a plurality of dipole magnets.

In another aspect, a method for generating a free electron laser is disclosed.

The method of generating a free electron laser includes: scanning an electron beam using an injector, accelerating the electron beam scanned from the injector using a linear accelerator, and an electron beam passing through the linear accelerator using a first path change unit. Changing the path of progression, compressing the electron bundle included in the electron beam passing through the first path changing unit in the longitudinal direction using a bunch compressor, the electron beam passing through the bunch compressor using an undulator and an electromagnetic field And generating a free electron laser by the interaction of and changing a traveling path of the electron beam passing through the undulator using a second path changing unit to enter the linear accelerator.

The method may further include expanding the bundle of electrons included in the electron beam passing through the undulator in a longitudinal direction using a bunch decompressor provided between the second path changing unit and the undulator. .

In the method, a high energy electron beam among electron beams passing through the linear accelerator is incident to the first path changing unit using a dump section provided between the linear accelerator and the first path changing unit, and the low energy electron beam is It may further include a step of dumping.

The method may further include changing a path of an electron beam scanned by the injector using a merging unit provided between the linear accelerator and the injector to enter the linear accelerator.

In another aspect, an apparatus for generating a free electron laser is disclosed. The disclosed free electron laser generator includes an injector that scans an electron beam, a first linear accelerator that accelerates or decelerates electrons using an electromagnetic field, and passes through the first linear accelerator. A first spreader that causes electrons included in the electron beam to be incident to different path changing units according to the energy level, and a plurality of path changing units connected to the first spreader by changing a traveling path of electrons passing through the first spreader , A second linear accelerator that accelerates or decelerates electrons using an electromagnetic field as an electron beam passing through at least one of the plurality of path changing units connected to the first spreader is incident, and a plurality of path changes connected to the first spreader. It includes an undulator for generating a free electron laser by the interaction of an electron beam passing through any one of the parts and an electromagnetic field.

The free electron laser generating device includes a second spreader for incidence of electrons included in the electron beam passing through the second linear accelerator to different path changing units according to an energy level, and a plurality of path changing units connected to the second spreader. It may contain more.

The free electron laser generating device may further include a path changing unit connected to the undulator to change a path of an electron beam passing through the undulator.

According to at least one embodiment, it is possible to generate a high-power extreme ultraviolet free electron laser. According to at least one embodiment, energy efficiency may be improved by recovering energy of an accelerated electron beam and then using it to accelerate other electrons. According to at least one embodiment, in the process of generating the free electron laser, physical quantities, such as an electron beam path, an emittance, a chirp, and a longitudinal current profile, can be effectively controlled.

Fig. 1 is a conceptual diagram showing a layout of an apparatus for generating a free electron laser according to an exemplary embodiment.
2 is a diagram showing the layout and simulation results of the injector.
3 is a diagram showing a simulation result.
4 is a diagram showing a simulation result.
5 is a conceptual diagram showing a path change due to a difference in energy of electrons in a bending magnet.
6 is a conceptual diagram illustrating an exemplary configuration of a first path change unit.
7 is a diagram showing a simulation result for a first path change unit.
8 is a conceptual diagram illustrating an exemplary configuration of a bunch compressor.
9 is a diagram showing a simulation result for a bunch compressor.
10 is a diagram illustrating an exemplary configuration of a FODO cell included in an undulator.
11 is a diagram showing a simulation result for an undulator.
12 shows a simulation result for an electron beam passing through a bunch decompressor.
Fig. 13 is a conceptual diagram showing a layout of an apparatus for generating a free electron laser according to another exemplary embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed description of the present invention to be described later refers to the accompanying drawings, which illustrate specific embodiments in which the present invention may be practiced in order to clarify the objects, technical solutions and advantages of the present invention. These embodiments are described in detail enough to enable a person skilled in the art to practice the present invention. In the description with reference to the accompanying drawings, the same reference numerals are assigned to the same components regardless of the reference numerals, and redundant descriptions thereof are omitted.

Specific structural or functional descriptions of the embodiments are disclosed for illustrative purposes only, and may be changed in various forms and implemented. Accordingly, the embodiments are not limited to a specific disclosure form, and the scope of the present specification includes changes, equivalents, or substitutes included in the technical idea.

Although terms such as first or second may be used to describe various components, these terms should be interpreted only for the purpose of distinguishing one component from other components. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

When a component is referred to as being "connected" to another component, it is to be understood that it may be directly connected or connected to the other component, but other components may exist in the middle.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate that the described features, numbers, steps, actions, components, parts, or combinations thereof exist, but one or more other features, numbers, and steps It is to be understood that it does not preclude the possibility of addition or presence of, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms, including technical or scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the relevant technical field. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this specification. Does not.

The present invention covers all possible combinations of the embodiments indicated herein. It should be understood that the various embodiments of the present invention are different from each other, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. In addition, it is to be understood that the location or arrangement of individual components in each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description to be described below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scopes equivalent to those claimed by the claims. Like reference numerals in the drawings refer to the same or similar functions over several aspects.

Unless otherwise indicated in this specification or clearly contradicting the context, items referred to in the singular encompass the plural unless otherwise required by that context. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to allow those skilled in the art to easily implement the present invention.

Fig. 1 is a conceptual diagram showing a layout of an apparatus 100 for generating a free electron laser according to an exemplary embodiment. The free electron laser generator of FIG. 1 may generate a free electron laser using an energy recovery linear accelerator (ERL).

Referring to FIG. 1, the free electron laser generating device 100 is an injector 110 that injects an electron beam having a predetermined energy level, and electrons scanned from the injector 110 are incident on the linear accelerator 120. The high-energy electron beam among the electrons emitted from the merger 112, the linear accelerator 120 that accelerates or decelerates free electrons using an electromagnetic field, and the linear accelerator 120 is a first path changer 140 ) And the low energy electron beam is dumped, the first path changing unit 140 for changing the traveling path of the electron beam incident from the dump section 130, the first path changing unit A bunch compressor (150) that compresses electron bunches included in the electron beam emitted from 140 in a longitudinal direction, and the electron beam emitted from the bunch compressor 150 and the electromagnetic field are mutually An undulator 160 that generates a free electron laser by the action, and a bunch decompressor that expands (that is, decompresses) the whole bundle bundle included in the electron beam emitted from the undulator 160 in the longitudinal direction. A bunch decompressor 170 and a second path change unit 180 for changing a path of an electron beam emitted from the bunch decompressor 170 may be included.

The injector 110 may scan an electron beam.

2 is a diagram showing the layout and simulation results of the injector.

2A shows an exemplary layout of the injector 110. In addition, (b) of FIG. 2 shows a change in the beam size according to the traveling direction of the beam generated from the injector 110. FIG. 2C shows a change in normalized emittance according to the traveling direction of the beam generated from the injector 110. 2D shows the change in length of the electron bundle according to the traveling direction of the beam generated from the injector 110. 2B to 2D are results obtained through ASTRA simulation.

The injector 110 may include a DC photocathode gun, a plurality of solenoids, a buncher cavity, and a plurality of Superconducting RF cavities. In FIGS. 2B to 2D, the number of solenoids included in the injector 110 is set to two and a simulation result is obtained, but the number of solenoids included in the injector may vary.

The direct current photoelectric cathode gun of the injector 110 can generate a charge bundle of approximately 40 pC and accelerate the generated charge bundle to a voltage of 960 kV and a repetition rate of 1.3 GHz. In order to reduce the emittance of the beam, solenoids (eg, two solenoids) included in the injector 110 may induce emittance compensation through transverse focusing. The emittance compensation effect may be a reduction in a projected emittance generated by overlapping distributions of a low beam slice in a phase space. The buncher cavity may have a repetition rate of approximately 1.3 GHz, but this is only exemplary, and embodiments are not limited thereto. The buncher cavity can change the length of the beam by manipulating the longitudinal phase space of the beam. The phase of the cavity can be defined by the ASTRA AUTOPHASE function. The phase 0° can be defined based on the position where the electron has the greatest kinetic energy. Once the phase 0° is defined, the simulation can be performed by increasing the phase by 10° to find the optimal combination of the beam length and the emittance. The booster of the injector 110 may include a plurality of SRF cavities (eg, five SRF cavities). The phase of the SRF cavities included in the booster may be defined the same as the phase of the buncher cavity. Among the cavities included in the injector 110, the phases of the cavities other than the first cavity may be the same as 0°. The phase of the first cavity may have a negative phase, and its value may be approximately -56.4°, but embodiments are not limited thereto.

The merging unit 112 may cause the electron beam scanned by the injector 110 to be incident on the linear accelerator 120. The merging unit 112 may include a plurality of quadrupole magnets and a plurality of bending magnets. For example, the merging unit 112 may include two quadrupole magnets and three bending magnets. The number of magnets included in the merging unit 112 may be changed within a range that can be easily changed by a person skilled in the art.

의 값은 대략 -0.089m일 수 있다. 여기서, R은 1차 오더까지를 고려해서, 제1 위치에서 빔의 물리적 파라미터로부터 제 2 위치에서의 빔의 물리적 파라미터를 도출하는 계산에서 이용되는 텐서일 수 있다.

은 상술한 R 텐서의 5, 6 성분을 의미할 수 있다.The merging unit 112 may perform a function of compressing a beam in addition to a beam transmission function. The merging unit 112 may be designed such that the angle at which the beam is bent is 20° or more (for example, 21°) in order to maintain the emittance of the beam from dispersion of the beam. This design can be referred to as an achromatic design. In Fig. 2(a)

The value of may be approximately -0.089m. Here, R may be a tensor used in calculation for deriving the physical parameter of the beam at the second position from the physical parameter of the beam at the first position in consideration of up to the first order.

May mean 5 and 6 components of the above-described R tensor.

로 계산될 수 있다. 전자 빔의 종방향(longitudinal) 분포도 가우시안 분포를 따르며 rms 다발(bunmch)의 길이가 대략 0.93mm로 계산될 수 있다. 상술한 시뮬레이션 결과들은 도 2의 (b) 내지 (d)를 통해 확인할 수 있다. In performing the simulation, the ASTRA particle tracking code can be used from the direct current photoelectric cathode gun to the entrance of the merging unit 112 in order to take into account the space charge effect in the low energy region. As a result of the simulation, under the design conditions of the injector 110 and the merging unit 112 described above, the transverse distribution of the electron beam followed a Gaussian distribution, and the emittance normalized at the end of the SRF cavity was approximately

Can be calculated as The longitudinal distribution of the electron beam also follows a Gaussian distribution, and the length of the rms bundle can be calculated to be approximately 0.93 mm. The simulation results described above can be confirmed through (b) to (d) of FIG. 2.

After the beam is generated, the emittance of the beam can be degraded due to the spreading of the beam by the space charge effect. However, according to an exemplary embodiment, while the beam passes through the SRF cavity and the solenoid included in the injector 110, the beam may be focused on a narrow area by a radial focusing force. As a result, the emittance of the beam is compensated and the emittance may not be reduced.

Results at the ends of the RF cavities obtained by ASTRA simulation during the simulation process can be converted into a format applicable to ELEGANT simulation.

3 is a diagram showing a simulation result.

3A shows the longitudinal phase space according to the traveling direction of the beam at the entrance of the merging unit 112. 3B shows the current of the beam according to the traveling direction of the beam at the entrance of the merging unit 112. 3C shows the emittance of the beam according to the traveling direction of the beam at the entrance of the merging unit 112, the blue line indicates the horizontal emittance, and the red line indicates the vertical emittance. 3(d) shows the inclination in the horizontal direction (blue) and inclination in the vertical direction (red) of the beam according to the traveling direction of the beam at the entrance of the merging unit 112. 3E shows the longitudinal phase space according to the traveling direction of the beam at the exit of the merging unit 112. 3F shows the current of the beam according to the traveling direction of the beam at the exit of the merger unit 112. 3(g) shows the emittance of the beam according to the traveling direction of the beam at the exit of the merging unit 112, the blue line indicates the horizontal emittance, and the red line indicates the vertical emittance. 3(h) shows the horizontal direction inclination (blue) and the vertical direction inclination (red) of the beam according to the traveling direction of the beam at the exit of the merger 112.

에 비례하는 고차 효과

에 의한 영향은 작을 수 있다. 또한, 압축에 의해 빔의 첩의 형상은 비 압축 빔의 첩보다 큰 곡률을 가질 수 있다. 압축 후 전류의 최대 값은 25A 정도로 계산되며, 전류의 모양은 양의 z 방향으로 비대칭 적일 수 있다. 굽힘각이 21 °로 증가하였음에도

에 비례하는 고차 효과

에 의한 영향은 클 것이라 예상되었으나 시뮬레이션 결과 그 영향은 크지 않을 수 있다. 도 3의 (c) 및 (g)를 참조하면

에 비례하는 수평 분산은 발견되지 않았으며

은 작을 수 있다.3, in the longitudinal direction (z direction)

Higher order effect proportional to

The effect of can be small. In addition, the shape of the chirp of the beam may have a larger curvature than that of the uncompressed beam by compression. The maximum value of the current after compression is calculated around 25A, and the shape of the current may be asymmetric in the positive z direction. Even though the bend angle increased to 21°

Higher order effect proportional to

It is expected that the effect of is large, but the effect may not be large as a result of simulation. Referring to Figure 3 (c) and (g)

No horizontal variance proportional to

Can be small.

,

으로 두 값이 모두 충분히 작을 수 있다. 이미턴스는 수평 및 수직 방향으로 모두

내로 보존될 수 있다. 슬라이스 에너지 스프레드(slice energy spread)는 0.01까지 증가할 수 있지만, 이는 후술하는 선형가속기(120)에 의해 보상될 수 있다.Simulation results

,

As such, both values can be sufficiently small. The emittance is in both horizontal and vertical directions.

Can be preserved within. The slice energy spread may increase to 0.01, but this may be compensated for by a linear accelerator 120 to be described later.

The linear accelerator 120 may include a plurality of superconducting modules. In FIG. 1, a case in which the linear accelerator 120 includes five superconducting modules is illustrated, but the embodiment is not limited thereto. Each superconducting module may include a plurality of cells and a quadrupole magnet. The quadrupole is included in the superconducting module and can be made superconducting. Each of the superconducting modules may include eight cells, but the number of specific cells may vary.

The linear accelerator 120 may accelerate an electron beam of a low energy level. For example, the linear accelerator 120 may accelerate electrons so that the kinetic energy of the electrons ranges from 15 MeV to 638 MeV. The chirp defined by the slope of the longitudinal phase space may be related to the performance of the linear accelerator 120, and the phase of the RF cavity included in the linear accelerator 120 determines the chirp, so the phase of the RF cavity can be properly set. There is a need. If the phase of the RF cavity is large, the amplitude of the electric field can be lowered, thereby reducing cost. However, in this case, since the distribution of the beam becomes uniform, the beam may not be compressed by the bunch compressor 150. Conversely, if the phase of the RF cavity is small, a high-amplitude electric field is required, and the chirp can appear strong. Strong chirps can cause high dispersion effects. Therefore, the phase of the RF cavity must be set to an appropriate value, and the value may be approximately 70°. In this case, the maximum energy dispersion of the beam may be approximately 0.01.

4 is a diagram showing a simulation result.

4A shows the layout of the linear accelerator 120 and the corresponding Twiss parameter change (red: horizontal axis, black: vertical axis). 4B shows the layout of the dump section 130 and the corresponding Twiss parameter change (red: horizontal axis, black: vertical axis). 4C shows the current profile of the beam according to the traveling direction of the beam at the exit of the compressor of the merger unit. 4D shows the phase space in the longitudinal direction of the beam according to the traveling direction of the beam at the exit of the compressor of the merging unit. 4E shows the current profile of the beam according to the traveling direction of the beam at the exit of the dumping section. 4F shows the longitudinal phase space of the beam according to the traveling direction of the beam at the exit of the dumping section.

,

일 수 있다. 또한 도 4의 (c) 및 (e)를 참조하면 종방향으로 전류분포가 날카로워져서 전류의 피크 값이 대략 25A에서 대략 40A로 증가할 수 있다.4(d) and (f), the average kinetic energy of electrons by the linear accelerator 120 can be increased to 630 MeV, and at the end of the linear accelerator 120

,

Can be In addition, referring to FIGS. 4C and 4E, the current distribution is sharpened in the longitudinal direction, so that the peak value of the current may increase from about 25A to about 40A.

According to the simulation, a focusing field may exist in the radial RF field direction in the linear accelerator 120. Linear matching may be difficult because the high-order effect of the linear accelerator 120 increases at low energy. In addition, since it affects the quadrupole decelerating electron beam of the linear accelerator 120, the optimization needs to be performed as weakly as possible. The linear accelerator 120 may transmit a beam having a stable longitudinal distribution to the first path change unit 140 through the above-described process.

The dump section 130 may dump an electron beam of low energy among electron beams emitted from the linear accelerator 120 and cause the electron beam of high energy to enter the first path change unit 140. The high energy electron beam accelerated in the previous period and the newly incident low energy electron beam may be incident on the linear accelerator 120. The high energy electron beam and the low energy electron beam have different phases and may be incident on the linear accelerator 120. The linear accelerator 120 can decelerate electrons of high energy (ex. 630 MeV). In this process, the linear accelerator 120 may recover the kinetic energy of electrons. The linear accelerator 120 can accelerate electrons of low energy (ex. 15 MeV). For example, the linear accelerator 120 may increase the kinetic energy of electrons from 15 MeV to 630 MeV.

The dump section 130 may include an achromat section and a matching section. The acromet section can bend the electrons decelerated by the linear accelerator 120 at a large angle and discard them, and transfer the electrons accelerated by the linear accelerator 120 to the first path change unit 140 without increasing the emittance. have. The acromet section may include a plurality of bending magnets. In FIG. 1, the acremet section exemplarily shows a case including four bending magnets, but the embodiment is not limited thereto. The first bending magnet included in the acromet section can change the path of low-energy electrons to be larger than that of high-energy electrons. For example, the first bending magnet may bend a path of an electron having a kinetic energy of 15 MeV by 5°, and a path of an electron of 630 MeV by 0.1°.

As shown in FIG. 1, the remaining three bending magnets except for the first bending magnet of the acromet section may be aligned in an S shape. A matching section may be disposed behind the bending magnets. The matching section may include a plurality of quadrupole magnets. For example, the matching section may include six quadrupole magnets. The matching section may adjust the Twiss parameter according to the periodic condition of the first path changing unit 140. The Twiss parameter may be a parameter associated with the emittance of each particle.

5 is a conceptual diagram showing a path change due to a difference in energy of electrons in a bending magnet.

와 벤딩 각도

를 가지는 벤딩 마그넷에서 전자들의 에너지 차이로 인해 전자들의 경로 차이가 발생할 수 있다. O는 벤딩 마그넷의 중심이고 전자 빔은 A에 수직으로 입사할 수 있다. 전자가 이상적인 에너지를 가지고 있을 경우, 전자는 원운동 후 B를 통과할 수 있다. 하지만 에너지 분산의 크기가

인 경우, 전자 경로의 반경은 자기 강성(magnetic rigidity)의 정의에 의해 수학식 1과 같이 표현될 수 있다.5, radius

And bending angle

Path differences of electrons may occur due to energy differences between electrons in a bending magnet having a. O is the center of the bending magnet and the electron beam can enter A perpendicularly. If an electron has ideal energy, the electron can pass through B after circular motion. But the amount of energy dissipation

In the case of, the radius of the electron path may be expressed as Equation 1 by the definition of magnetic rigidity.

는 벤딩 마그넷의 반지름을 의미하고,

는 자기장을 의미하고

는 전자의 이상적인 모멘텀을 의미하며,

는 전자의 전하량을 의미한다. 도 5에서

을

에 수직으로 입사한 후 운동량

를 가지는 전자가 통과하는 지점이라 두면, 자기장 내부에서 전자는

을 중심으로 원형으로 움직이고 벤딩 각은

일 수 있다. 여기서,

에서 원호

의 접선과 가로축 사이의 접점이

이 될 수 있고,

,

,

이 이루는 각도는 90도일 수 있다. 또한,

에서 원호

의 접선과 가로축 사이의 접점이

가 될 수 있고,

가 이루는 각도도 90도가 될 수 있다. 따라서, 엣지 각과

,

,

로 정의되는 각도는 평행이동시 동일할 수 있다. 엣지 각은

일 수 있다. 삼각형

,

,

에 대한 코사인 제2 법칙으로부터 엣지각은 수학식 2와 같이 계산될 수 있다. In Equation 1

Means the radius of the bending magnet,

Means magnetic field and

Denotes the electron's ideal momentum,

Means the amount of charge of an electron. In Figure 5

of

Momentum after incident perpendicular to

Let's say that it is the point through which an electron with is passed, the electron inside the magnetic field

It moves in a circle around and the bending angle is

Can be here,

Arc from

The contact point between the tangent of and the horizontal axis

Can be,

,

,

The angle formed by this may be 90 degrees. Also,

Arc from

The contact point between the tangent of and the horizontal axis

Can be,

The angle formed by may also be 90 degrees. Therefore, the edge angle and

,

,

The angle defined as can be the same when moving in parallel. The edge angle is

Can be triangle

,

,

From the second law of cosine for, the edge angle can be calculated as in Equation 2.

,

로 계산될 수 있다. 매칭 섹션에서 Twiss 파라미터는

,

로 계산될 수 있다. 수평, 수직 이미턴스와 rms 번치 길이 및 슬라이스 에너지 스프레드는 각각

일 수 있다.Considering the difference in beam energy, the edge angle may be 0.1°. In the Acrobat section, the eta function is

,

Can be calculated as In the matching section, the Twiss parameter is

,

Can be calculated as The horizontal and vertical emittance and rms bunch length and slice energy spread are respectively

Can be

6 is a conceptual diagram illustrating the configuration of the first path change unit 140 by way of example.

Referring to FIG. 6, the first path change unit 140 includes two cells, and the overall structure of the first path change unit 140 may satisfy mirror symmetry. Each cell is periodic and may be designed to bend an electron beam by 90 degrees. Each cell may include a Triple Bend Achromat (TBA) portion and two pairs of quadrupole magnet sets arranged on both sides of the TBA. For example, two quadrupole magnets may be provided on each side of the TBA. In each cell, the quadrupole magnets provided on either side of the TBA can be symmetrical. For example, the first path change unit 140 may include 12 quadrupole magnets and 6 bending magnets. Each of the bending magnets included in the first path changing unit 140 may bend the path of the electron beam by 30°. Since the first path changing unit 140 with reference to FIG. 6 is designed isochronously, the emittance and the longitudinal distribution of the beam can be maintained. Also, chromatic aberration of the beam may not occur.

Equation 3 can be satisfied because of the mirror symmetry of the grating.

는 격자의 대칭 축의 위치를 의미한다. 거울 대칭성 때문에, 수학식 4에서 나타낸 바와 같이

은 대칭축에서 0이 되어야 한다.

Means the position of the axis of symmetry of the grid. Because of the mirror symmetry, as shown in Equation 4

Should be zero on the axis of symmetry.

라 하면,

는 수학식 5를 만족할 수 있다.Eta function and slope at the entrance of the bending magnet B2 shown in FIG. 5

If you say,

May satisfy Equation 5.

는 벤딩 마그넷의 벤딩 반지름을 나타내고,

는 벤딩 마그넷의 벤딩 각도를 나타낸다. 제1 경로 변경부(140)에서

은 사중극자 마그넷(Q3)의 세기

, 벤딩 마그넷(B1)과 사중극자 마그넷(Q3) 사이의 거리

및 벤딩 마그넷(B2)과 사중극자 마그넷(Q3) 사이의 거리

에 의해 결정될 수 있다.In Equation 4 and Equation 5

Represents the bending radius of the bending magnet,

Represents the bending angle of the bending magnet. In the first route change unit 140

The strength of the silver quadrupole magnet (Q3)

, Distance between bending magnet (B1) and quadrupole magnet (Q3)

And the distance between the bending magnet (B2) and the quadrupole magnet (Q3)

Can be determined by

7 is a diagram illustrating a simulation result of the first path change unit 140.

In (a) of FIG. 7, a red line indicates a Twiss parameter for a horizontal direction, and a black line indicates a Twiss parameter for a vertical direction. FIG. 7(b) shows a current profile with respect to the moving direction of the beam at the entrance of the first path changing unit 140, and FIG. 7(c) is the moving of the beam at the entrance of the first path changing unit 140 The longitudinal space of the beam with respect to the direction is shown, and (d) of FIG. 7 shows the profile of the current with respect to the traveling direction of the beam at the exit of the first path changing unit 140, and (e) of FIG. It represents the longitudinal space of the beam with respect to the traveling direction of the beam at the exit of the path changing unit 140.

,

,

의 크기는 수학식 5의 (1), (2) 식들에 의해 정해졌다. 시뮬레이션에서

,

,

로 설정되었다. 도 7의 (a)에서 나타낸 바와 같이 Twiss 파라미터가 계산되었으며, 제1 경로 변경부(140)의 끝에서

,

,

이고

일 수 있다. 도 7의 (b) 및 도 7 (d)에서 보는 바와 같이 전자 다발(bunch)의 길이는

로부터

로 약간의 변화가 있을 수 있다. 전류의 최대치는 고차 효과

때문에 40A에서 35A로 감소할 수 있다. 도 7의 (c) 및 (e)를 참조하면, 첩의 선형성(linearity)는 거의 같을 수 있다. 빔의 이미턴스는

,

으로 모두

보다 작을 수 있다. 따라서, 빔의 이미턴스가 유지됨으로서 빔의 성능이 유지될 수 있다.In simulation

,

,

The size of was determined by equations (1) and (2) in Equation 5. In simulation

,

,

Was set to As shown in (a) of FIG. 7, the Twiss parameter was calculated, and at the end of the first path change unit 140

,

,

ego

Can be As shown in Fig. 7 (b) and Fig. 7 (d), the length of the electron bundle is

from

There may be some changes. The maximum value of the current is a higher order effect

Therefore, it can be reduced from 40A to 35A. Referring to FIGS. 7C and 7E, the linearity of the chirp may be approximately the same. The emittance of the beam is

,

By all

Can be smaller than Thus, the beam's performance can be maintained by maintaining the beam's emittance.

The beam emitted from the first path change unit 140 may be incident on the bunch compressor 150. The bunch compressor 150 may sharply or flatly change the distribution of the longitudinal current by using that the longitudinal energy distribution is not constant and is inclined.

8 is a conceptual diagram illustrating a configuration of a bunch compressor 150 by way of example.

Referring to FIG. 8, the bunch compressor 150 may include a first dipole magnet 152, a second dipole magnet 154, a third dipole magnet 156, and a fourth dipole magnet 158. The dipole magnets 152, 154, 156, 158 may be arranged in an S shape. When the length and the bending angle of the dipole magnet are determined, the path length of the electrons can be expressed as in Equation 6.

는 두 전자의 에너지 차(energy difference) 또는 운동량의 차(momentum difference)를 의미한다.In Equation 6

Denotes the energy difference or momentum difference between two electrons.

은 수학식 7과 같이 나타낼 수 있다.From Equation 6

Can be expressed as in Equation 7.

From Equation 7, the energy chirp of electrons can be expressed as Equation 8.

In Equation 8, h denotes an electron energy stack.

The rms bunch length compressed by the bunch compressor 150 can be expressed as in Equation 9.

는 압축후 rms 번치 길이를 나타내고

는 압축전 rms 번치 길이를 나타내고

는 에너지 스프레드를 나타내고,

는 이상적 에너지에 대한 상대론적 팩터를 의미한다. 실제 전자 빔은 z 포지션에 따라 다른 에너지 스프레드를 갖는다. 즉, 실제 전자빔은 완벽한 가우시안 분포를 따르지 않을 수 있다. 번치 컴프레서(150)가 잘 작동하기 위해서는 드리프트 길이(

) 및 각도(

)를 잘 조절하는 것이 중요하다. 벤딩 각도(

)가 크면 자기장의 세기와 고차 효과 및 CSR과 같은 군집효과(collective effect)가 강해질 수 있다. 굽힘각도가 8.4°이고, 드리프트 길이(

)를 2.2m로 설정하는 경우,

일 수 있다.In Equation 9

Represents the rms bunch length after compression

Represents the rms bunch length before compression

Represents the energy spread,

Denotes a relativistic factor for ideal energy. The actual electron beam has a different energy spread depending on the z position. That is, the actual electron beam may not follow a perfect Gaussian distribution. In order for the bunch compressor 150 to work well, the drift length (

) And angle (

) Is important. Bending angle(

If) is large, the intensity of the magnetic field, higher-order effects, and collective effects such as CSR may become stronger. The bending angle is 8.4°, and the drift length (

) Is set to 2.2m,

Can be

9 is a view showing a simulation result for the bunch compressor 150.

9A shows a current profile according to a traveling direction of a beam at an entrance of the bunch compressor 150. 9C shows the longitudinal profile of the beam according to the traveling direction of the beam at the entrance of the bunch compressor 150. 9B shows a current profile according to a traveling direction of a beam at an exit of the bunch compressor 150. 9D shows the longitudinal profile of the beam according to the traveling direction of the beam at the exit of the bunch compressor 150.

Referring to FIGS. 9A and 9B, the current distribution of the beam may be compressed in the longitudinal direction by the bunch compressor 150. Thus, the maximum value of the current can be increased from 35A to 630A. By compression, most of the electrons can be collected in a narrow area where the current is maximum.

The beam passing through the compressor 150 may be incident on the undulator 160. A matching section for adjusting the Twiss parameter may be further provided between the compressor 150 and the undulator 160. The matching section may include six quadrupole magnets, but embodiments are not limited thereto.

The undulator 160 may emit electromagnetic radiation by performing a meandering motion of the incident electrons to the left and right using a magnetic field. The undulator 160 may emit an extreme ultraviolet (EUV) radiation beam. Ultraviolet radiation beams can be used in lithographic processes. By adjusting the period of the magnet included in the undulator 160 or the gap between the magnets, radiation having a wavelength longer or shorter than that of the extreme ultraviolet rays may be generated.

Given the total length and period of the undulator 160, the undulator parameter K defined by the strength of the magnetic field may be expressed as in Equation 10.

는 언듈레이터에서 방출되는 방사선 빔의 파장을 의미하고,

은 공진이 일어나 원하는 파장을 발생 시킬 때의 전자 빔의 에너지를 나타내며,

는 언듈레이터 주기(언듈레이터를 이루는 자석의 종방향 길이)를 의미한다. In Equation 10

Is the wavelength of the radiation beam emitted from the undulator,

Represents the energy of the electron beam when resonance occurs and generates a desired wavelength,

Means the undulator period (longitudinal length of the magnet forming the undulator).

값은 수학식 10에 따라 1.287로 설정되었다. 언듈레이터에 입사되는 전자 빔의 에너지와 언듈레이터 주기가 결정되면, 언듈레이터 내부에서의 전자빔의 베타 함수가 결정될 수 있다. 얇은 렌즈 근사법(thin lenses approximation)에 따르면 베타트론 함수의 최대값 및 최소값은 수학식 11 및 수학식 12와 같이 나타낼 수 있다.In simulation

The value was set to 1.287 according to Equation 10. When the energy of the electron beam incident on the undulator and the undulator period are determined, a beta function of the electron beam inside the undulator may be determined. According to the thin lenses approximation, the maximum and minimum values of the betatron function can be expressed as Equations 11 and 12.

는 위상 어드밴스(phase advance)를 의미하고,

f는 초점 거리로서

로 결정되며,

는 사중극자 마그넷의 세기이고,

은 마그넷의 길이를 의미한다. 시뮬레이션에서 위상 어드벤스는 35°로 설정되었고, 따라서,

,

일 수 있다. 이 값은 사중극자 마그넷의 세기에 의해서 조절이 가능하다. In Equations 11 and 12

Means phase advance,

f is the focal length

Is determined by

Is the strength of the quadrupole magnet,

Means the length of the magnet. In the simulation, the phase advance was set to 35°, so,

,

Can be This value can be adjusted by the strength of the quadrupole magnet.

The undulator 160 may include a plurality of FODO cells. For example, the undulator 160 may include five FODO cells, but the embodiment is not limited thereto.

(언듈레이터의 주기)의 배수에 해당할 수 있다.10 is a diagram illustrating an exemplary configuration of a FODO cell included in an undulator. Referring to FIG. 10, each FODO cell includes a first half quadrupole 161, a first undulating unit 163, a defocusing quadrupole 165, a second undulating unit 167, and It may include two anti-quadpoles 169. A first drift section 162 may be provided between the first reflective quadrupole 161 and the first undulating unit 163. A second drift section 164 may be provided between the defocusing quadrupole 165 and the first undulating unit 163. A third drift section 166 may be provided between the defocusing quadrupole 165 and the second undulating unit 167. A fourth drift section 168 may be provided between the second undulating part 167 and the second reflective quadrupole 169. As shown in FIG. 10, the size of each component of the undulator 160 is

It may correspond to a multiple of (undulator cycle).

11 is a diagram showing a simulation result for the undulator 160. The simulation was performed based on different random seed numbers and was performed 5 times.

In FIG. 11, each of the gray lines represents a simulation result based on a different random seed number, and a blue line represents an average of the simulation results.

11A shows the pulse power according to the position of the undulator. 10B shows the peak power at the outlet of the undulator. Fig. 10(c) shows the energy spectrum of the pulse shown in Fig. 10(b). 10D shows the Twiss parameter in the undulator. In (d) of FIG. 10, the red line represents the vertical beta function, and the black line represents the horizontal beta function.

Referring to FIG. 11A, the average of the pulse power is about 20 MW, but the actual pulse power may be about 27 MW. This may be because, unlike what was considered in the simulation, the actual electron beam contains a dummy current of 1 mm length to compensate for the escape of radiation from the electron beam. Since the repetition rate of the injector 110 is 1.3 GHz, the average output over all times may be approximately 37 kW. This is higher than the target power of 10 kW for the photolithography process. Further, the peak power may be about 0.5 GW, and the FWHM may be about 3 μm. Looking at the energy spectrum shown in (c) of FIG. 11, since the energy range is wide, the wavelength of the pulse may also be widely distributed. In (c) of FIG. 11, the peak value is approximately 91.74 eV, which means that the wavelength is longer than 13.51 nm and is within a 0.1% error range from 13.5 nm. Referring to (d) of FIG. 11, the grating is periodic and symmetric, but the Twiss parameter may not be completely periodic.

The beam passing through the undulator 160 may be incident on the bunch decompressor 170. The bunch decompressor 170 may have the same configuration as the bunch compressor 150. For example, the bunch decompressor 170 may include four dipole magnets. The bunch decompressor 170 may expand the current distribution of the electron beam in the longitudinal direction. The electron beam passing through the bunch decompressor 170 may be incident on the second path changing unit 180. The second path change unit 180 may include the same configuration as the first path change unit 140. The second path change unit 180 may change the traveling direction of the electron beam. The electron beam passing through the second path change unit 180 may be incident on the linear accelerator 120. The linear accelerator 120 may recover energy of an electron beam that has passed through the second path change unit 180.

12 shows a simulation result for an electron beam passing through a bunch decompressor.

12A shows a current profile according to a traveling direction of a beam at an entrance of a bunch decompressor. 12B shows a current profile according to a traveling direction of a beam at an entrance of a linear accelerator. 12C shows a current profile according to a traveling direction of a beam after energy recovery is performed. 12D shows a longitudinal phase space profile according to a traveling direction of a beam at an entrance of a bunch decompressor. 12(e) shows a longitudinal phase space profile according to the traveling direction of the beam at the entrance of the linear accelerator. 12(f) shows the longitudinal phase space profile according to the traveling direction of the beam after energy recovery is performed.

Referring to FIGS. 12A and 12B, the current distribution of the beam may be expanded in the longitudinal direction by the bunch decompressor 170. The maximum value of the current can be reduced from 600A to approximately 30A. While passing through the bunch decompressor 170, the chirping direction of the current may be reversed. Further, referring to (f) of FIG. 12, in the deceleration process of the linear accelerator 120, the electron beam may be decelerated to have energy before acceleration. After the deceleration process, the average energy of the electron is about 14.5 MeV, and the energy of the electron can be recovered before acceleration.

Fig. 13 is a conceptual diagram showing a layout of a free electron laser generating apparatus 200 according to another exemplary embodiment.

13, the free electron laser generator 200 includes an injector 210, a first linear accelerator 222, a second linear accelerator 224, a first spreader 230, and a first linear accelerator 222. And a plurality of path changing units 242a, 244a, 246a, 248a, 249a connected to the first end (ex. the right side of Fig. 13) of the second linear accelerator 224, the undulator 250, the second spreader 260 ) And a second stage (ex. the left side of FIG. 13) of the first linear accelerator 222 and the second linear accelerator 224, and a plurality of path changing units 242b, 244b, 246b, 248b, 249b. have.

According to the embodiment of FIG. 13, the beam scanned by the injector 210 may be accelerated at least twice or more by the first and second linear accelerators 222 and 224. Therefore, the length of the linear accelerator can be reduced compared to the embodiment shown in FIG. 1. The lengths of the first and second linear accelerators 222 and 224 of FIG. 13 may be smaller than the length of the linear accelerator 120 of FIG. 1. For example, the length of the first and second linear accelerators 222 and 224 of FIG. 13 may be approximately 9 m, while the length of the linear accelerator 120 illustrated in FIG. 1 may be approximately 45 m.

The injector 210 may scan an electron beam. Electrons scanned by the injector 210 may have kinetic energy of approximately 15 MeV. The electron beam scanned by the injector 210 may be incident on the first linear accelerator 222. The first linear accelerator 222 may accelerate the electron beam scanned from the injector 210. The first spreader 230 may cause electrons included in the electron beam that has passed through the first linear accelerator 222 to be incident in different paths according to the energy level. For example, the first spreader 230 may dump an electron beam having a first energy (eg, approximately 15 MeV). The first spreader 230 may cause an electron beam having a second energy (eg, approximately 140 MeV) to be incident on the path change unit 242a. The first spreader 230 may cause an electron beam having a third energy (eg, approximately 265 MeV) to be incident on the path change unit 244a. The first spreader 230 may cause an electron beam having the fourth energy (eg, approximately 390 MeV) to be incident on the path change unit 246a. The first spreader 230 may cause an electron beam having the fifth energy (eg, approximately 515 MeV) to be incident on the path change unit 248a. The first spreader 230 may cause an electron beam having the sixth energy (eg, approximately 640 MeV) to be incident on the path change unit 249a.

The electron beam passing through the path changing units 242a, 244a, 246a, and 248a may be incident on the second linear accelerator 224. The electron beam may be accelerated again by the second linear accelerator 224. The second spreader 260 may cause the electron beam that has passed through the second linear accelerator 224 to be incident to a different path change unit according to an energy level. For example, the second spreader 260 may cause an electron beam having a second energy (eg, approximately 140 MeV) to be incident on the path change unit 242b. The second spreader 260 may cause an electron beam having a third energy (eg, approximately 265 MeV) to be incident on the path change unit 244b. The second spreader 260 may cause an electron beam having the fourth energy (eg, approximately 390 MeV) to be incident on the path change unit 246b. The second spreader 260 may cause an electron beam having the fifth energy (eg, approximately 515 MeV) to be incident on the path change unit 248b.

The electron beam may be accelerated multiple times by the first and second linear accelerators 222 and 224 until it has a predetermined energy (eg, 640 MeV). The electron beam passing through the path change unit 249a may be incident on the undulator 250. The undulator 250 may emit electromagnetic radiation by meandering the incident electrons to the left and right using a magnetic field.

The electron beam passing through the undulator 250 may be incident on the path changing unit 249b. The electron beam passing through the path changing unit 249b may be incident on the first linear accelerator 222. The electrons passing through the path change unit 249b may have kinetic energy of approximately 640 MeV, and may be decelerated by the first linear accelerator 222. According to the above-described embodiment, the electron beam scanned from the injector 210 may be accelerated while passing through the first and second linear accelerators 222 and 224 a plurality of times. Accordingly, the lengths of the first and second linear accelerators 222 and 224 can be shortened.

The apparatus for generating a free electron laser according to exemplary embodiments has been described above with reference to FIGS. 1 to 13. According to at least one embodiment, it is possible to generate a high-power extreme ultraviolet free electron laser. According to at least one embodiment, energy efficiency may be improved by recovering energy of an accelerated electron beam and then using it to accelerate other electrons. According to at least one embodiment, in the process of generating the free electron laser, it is possible to effectively control physical quantities such as an electron beam path, an emittance, a chirp, and a longitudinal current profile.

In the above, the present invention has been described by specific matters such as specific components and limited embodiments and drawings, but this is provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, Anyone with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations from this description.

Therefore, the spirit of the present invention is limited to the above-described embodiments and should not be defined, and all modifications equivalent or equivalent to the claims as well as the claims appended to the present disclosure are the spirit of the present invention. It will be said to belong to the category of. For example, the described techniques are performed in a different order from the described method, and/or components such as a system, structure, device, circuit, etc. described are combined or combined in a form different from the described method, or other components Alternatively, even if substituted or substituted by an equivalent, an appropriate result can be achieved.

Such equivalently or equivalently modified ones will include, for example, logically equivalent methods capable of producing the same results as those of carrying out the method according to the present invention. The scope should not be limited by the examples described above, but should be understood in the broadest possible sense by law.

Claims (19)

In the free electron laser generator,
An injector that scans an electron beam;
A linear accelerator to which an electron beam passing through the injector is incident, and accelerating or decelerating electrons using an electromagnetic field;
A first path changing unit for changing a traveling path of the electron beam passing through the linear accelerator;
A bunch compressor for compressing electron bunches included in the electron beam passing through the first path change unit in a longitudinal direction;
An undulator for generating a free electron laser by the interaction of an electromagnetic field and an electron beam passing through the bunch compressor; And
A free electron laser generator comprising a second path changing unit for changing a traveling path of the electron beam passing through the undulator and entering the linear accelerator. The method of claim 1,
A free electron laser generating apparatus further comprising a bunch decompressor provided between the second path changing unit and the undulator and extending the bundle of electrons included in the electron beam passing through the undulator in the longitudinal direction . The method of claim 1,
Further comprising a dump section provided between the linear accelerator and the first path changing unit, for allowing a high-energy electron beam of electron beams passing through the linear accelerator to enter the first path changing unit and dumping the low energy electron beam. Free electron laser generator. The method of claim 3,
The dump section includes a plurality of bending magnets, and at least one of the plurality of bending magnets bends the high energy electron beam and the low energy electron beam at different angles. The method of claim 1,
A free electron laser generator further comprising a merging unit for changing the path of the electron beam scanned by the injector to be incident on the linear accelerator. The method of claim 5,
The merging unit free electron laser generator comprising a plurality of quadrupole magnets and a plurality of bending magnets. The method of claim 1,
The linear accelerator accelerates the low-energy electron beam scanned from the injector and decelerates the high-energy electron beam that has passed through the second path changing unit to recover kinetic energy. The method of claim 7,
The linear accelerator increases or decreases the energy value of the electron beam passing through the linear accelerator by changing the energy of the electron beam passing through the linear accelerator. The method of claim 8,
The linear accelerator is a free electron laser generator comprising a plurality of modules having the same structure. The method of claim 1,
Each of the first path changing unit and the second path changing unit includes a plurality of cells, and has a mirror-symmetric structure. The method of claim 10,
Each of the plurality of cells generates a free electron laser including a TBA (Triple Bend Achromat) portion including a plurality of bending magnets and a plurality of quadrupole magnets, and a plurality of quadrupole magnets symmetrically arranged on both sides of the TBA portion Device. The method of claim 1,
The bunch compressor is a free electron laser generator comprising a plurality of dipole magnets. In the free electron laser generation method,
Scanning an electron beam using an injector;
Accelerating the electron beam scanned from the injector using a linear accelerator;
Changing a traveling path of the electron beam passing through the linear accelerator using a first path changing unit;
Compressing the electron bundle included in the electron beam passing through the first path changing unit in the longitudinal direction using a bunch compressor;
Generating a free electron laser by an interaction between an electron beam passing through the bunch compressor and an electromagnetic field using an undulator;
And changing a traveling path of the electron beam passing through the undulator using a second path changing unit and causing the electron beam to enter the linear accelerator. The method of claim 13,
The method of generating a free electron laser further comprising expanding the electron bundle included in the electron beam passing through the undulator in a longitudinal direction using a bunch decompressor provided between the second path changing unit and the undulator. The method of claim 13,
Using a dump section provided between the linear accelerator and the first path changing unit, among electron beams passing through the linear accelerator, a high energy electron beam is incident to the first path changing unit, and a low energy electron beam is dumped. Free electron laser generating method further comprising. The method of claim 13,
The method of generating a free electron laser further comprising the step of changing a path of an electron beam scanned by the injector using a merger provided between the linear accelerator and the injector to enter the linear accelerator. In the free electron laser generator,
An injector that scans an electron beam;
A first linear accelerator to which the electron beam passing through the injector is incident, and accelerating or decelerating electrons using an electromagnetic field;
A first spreader for causing electrons included in the electron beam passing through the first linear accelerator to be incident to different path changing units according to energy levels;
A plurality of path changing units connected to the first spreader for changing a path of electrons passing through the first spreader;
A second linear accelerator for accelerating or decelerating electrons by using an electromagnetic field to which an electron beam passing through at least one of a plurality of path changing units connected to the first spreader is incident; And
A free electron laser generator comprising an undulator configured to generate a free electron laser by an interaction between an electron beam passing through any one of a plurality of path changing units connected to the first spreader and an electromagnetic field. The method of claim 17,
A second spreader for causing electrons included in the electron beam passing through the second linear accelerator to be incident to different path changing units according to energy levels; And
A free electron laser generator further comprising a plurality of path changing units connected to the second spreader. The method of claim 18,
The free electron laser generating apparatus further comprises a path changing unit connected to the undulator and changing a path of the electron beam passing through the undulator.

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