TWI423738B - A method and apparatus for generating high density hollow electron cloud instantaneously by laser - Google Patents

Description

Method and device for generating high-density hollow electron cloud by laser moment

The invention relates to a device for generating a hollow electron cloud, in particular to a method and a device for generating a high-density hollow electron cloud instantaneously by laser.

On a time- and space-limited charged bunch, an electron bunch with a strong ray intensity is accelerated to a high energy exceeding hundreds of millions of electron volts (GeV) in a short distance. Since the mid-1950s, researchers have come up with inventions and recommendations. For example, Bennett of the United States first proposed an acceleration method for electron bunching. However, the scheme proposed by the Soviet Union's Veksler is clear and easy to accelerate electron bunching in a short distance.

The Geneva International Accelerator Conference in 1950, the Soviet Union's Dubna, Veksler and Budker jointly published ion acceleration theory and experiments on charged particles using high-intensity, high-density electron bunching. .

As used herein, an ion, meaning all charged ions including a proton, referred to as a heavy ion, refers to a charged ion having a weight greater than 氦 on the elemental table.

At the 1967 Cambridge Accelerator International Conference, the Soviet Union's Veksler published an induction linac model that accelerated the 10 billion protons from a distance of 15 m to 1 GeV.

This revolutionary ion/electron bunching acceleration method has caused major research institutes around the world to rush into relevant theories and experiments. For example, the Lawrence Berkley Laboratory (LBL, LA) published the Electron Ring Accelerator (ERA) system; the University of Maryland focused on the electron beam accelerator (ERA) for studying high-intensity electron beams. The inventor of the electronic circle and induced linear accelerator, Christfilos, launched the Nuclear Fusion Technology Development Electronic Circle Accelerator (ERA) at the Lawrence Livermore National Laboratory.

The working principle of the so-called electron ring accelerator (ERA), as shown in Fig. 1, first injects an unneutralized electron beam into a longitudinal magnetic field with a slight focusing effect to form an electron circle. Thereafter, the magnetic field strength rises with time to compress the long and short radii of the electron ring in the magnetic field and further increase the electron energy in the electron circle. At this time, since the electrons of the electron circle collide with the gas molecules to generate a large amount of ions, and the ions are captured by the energy barrier of the electron circle, on the one hand, the space charge force of the electron is neutralized, so that the electron circle maintains the shape; On the other hand, it also provides that the electron circle and the ions it captures accelerate at the same time.

There are two ways to accelerate the electron ring and the ions it captures simultaneously: one is to use the accelerating cavity to produce an electric field along the direction of the magnetic field line, and the other is to use the Lorentz force of the radial component of the magnetic field that gradually decreases along the longitudinal distance. Therefore, the above-mentioned electron ring and the ions it captures can be accelerated at a large rate of acceleration, which is obviously limited and determined by the maximum electric field in the direction of the magnetic field lines and the ability to maintain ions in the electron ring.

Therefore, the current research direction for the electron horn accelerator (ERA) is to improve the retention ability of keeping ions in the electron circle. For example, the ion acceleration method of the electron ring accelerator (ERA) published by the Lawrence Berkeley Laboratory (LBL) in the United States uses a small and small convergence method to generate a time by one turh incident electron cyclotron. The changing axis magnetic field; the ion acceleration method of the electron ERA accelerator (ERA) published by A. Sessler is to generate a large electron ring on the cathode and then into the axis. The magnetic field of the static axis with reduced direction; and the ion acceleration method of the electron ring accelerator (ERA) published by the University of Maryland utilizes the generation of large hollow electron rays on the cathode and then into the Kasoff magnetic field ( Cusp magnetic field).

However, the ion acceleration method of any of the above-described electron ring accelerators (ERA) is mainly in the form of shortening the formed electron ring in the axial direction. In this case, the amount of current required is high, and various kinds of occurrences occur. For the problem of ray instability, it is extremely difficult to stabilize the electron bunch.

On the other hand, due to the mature development of large-scale synchrotron accelerators, high-energy proton accelerators, and linear electron and proton colliders in recent years, the electron-trap accelerator (ERA) that accelerates to hundreds of GeV or TeV fields with electrons and protons is used. Research and development have gradually declined.

Therefore, the main object of the present invention is to provide a method and apparatus for instantaneously generating a high-density hollow electron cloud by laser, which does not require injection of an electron beam into a longitudinal magnetic field to form an electron circle, thereby solving the foregoing The high current electron ring accelerator (ERA) described has the problem of electron ray instability.

The method for instantaneously generating a high-density hollow electron cloud by laser is to use two sets of laser devices to project laser beams of different wavelengths, respectively, and project them to a centrally located ion target source and an electron source surrounded by the periphery, so that electron generation occurs. The source instantaneously generates a hollow or hollow cylindrical electron bunch (or electron bunch or electron cloud) to capture an ion bunch instantaneously generated by the ion target source, and is enclosed in the generated electron bunching Within a very short distance, it can be accelerated to more than 100 MeV/m.

According to the above, the apparatus for generating a high-density hollow electron cloud by laser in the present invention includes: a first laser device for emitting a laser beam and causing an electron generating source to instantaneously generate an electron cloud; and a second laser device , for emitting a laser beam and causing the ion generating source to instantaneously generate an ion beam group; an annular optical cathode receiving a laser beam emitted by the first laser device to instantaneously generate a hollow or hollow cylindrical electron cloud; an ion target a source disposed at a center of the annular optical cathode and forming a concentric circle with the annular optical cathode, and a laser beam emitted by the second laser device is instantaneously generated and enclosed in the hollow or hollow cylindrical electron An ion cluster within the cloud.

The device for instantaneously generating a high-density hollow electron cloud by laser has the following advantages: no problem of electron beam instability, acceleration of ions at a very short distance, and shortening of an accelerator volume, and can be applied to a table for implementing radiation-resistant tumor treatment. Upper type therapy accelerator.

As shown in FIG. 2 and FIG. 3, the apparatus 10 for generating a high-density hollow electron cloud by laser in the present invention includes a first laser device 20, a second laser device 30, an ion target source 40, and a The annular optical cathode 50 is provided at the center of the annular optical cathode 50 and is concentric with the annular optical cathode 50.

The first laser device 20 is configured to emit a laser beam 25 of a predetermined wavelength, and when the emitted laser beam 25 is irradiated to an electron generating source such as the annular optical cathode 50, it is suitable for generating an electron cloud instantaneously by the electron generating source. .

The preferred embodiment of the first laser device 20 is suitably designed such that the light intensity of the central portion 26 of the emitted laser beam 25 is zero or weak, depending on the material and geometric configuration of the optical lens.

The second laser device 30 is configured to emit a laser beam 30 of a predetermined wavelength, but the wavelength of the emitted laser beam 30 is different from the laser beam 25 of the first laser device 20, and is suitable for the ion generation source to instantaneously generate an ion beam group. .

The ion target source 40 is used as an ion generating source, and is disposed at the center of the annular optical cathode 50 to form a target of the annular optical cathode 50, and receives the laser emitted from the second laser device 30. The ion beam cluster 65 is instantaneously generated when the light beam 35 is emitted.

The annular optical cathode 50 is used as an electron generating source and surrounds the periphery of the ion target source 40. When the electron generating source receives the laser beam 25 emitted from the first laser device 20, a high-density hollow is instantaneously generated. a hollow or cylindrical electron cloud 60, and rapidly capturing the ion cluster 65 instantaneously generated from the ion target source 40 by its own clone potential, and enclosing it in the generated hollow or hollow Within the cylindrical electron cloud 60.

When the cylindrical length of the hollow cylindrical electron cloud 60 is short, it conforms to the shape of the electronic ring of the conventional electron ring accelerator (ERA). Moreover, the hollow or hollow cylindrical electron cloud 60 and the captured ion cluster 65 can be extracted when subjected to magnetic field acceleration by an RF electric field or an electron ring accelerator (ERA). And instantaneously accelerating to the speed of light, and the accelerated hollow cylindrical electron cloud 60 and high energy ion beam cluster 65 can be separated by the proposal published by Bessler et al.

The energy of the ion cluster 65 is based on the spatial and temporal positional relationship between the hollow cylindrical electron cloud 60 and the ion cluster 65, mainly depending on the number of electrons of the hollow cylindrical electron cloud 60 and It can be determined by how many ion clusters 65 are held. Therefore, the spatial position and structure of the first laser device 20 and the second laser device 30, and the projection times of the two laser beams 25 and 35 of the first laser device 20 and the second laser device 30 can be adjusted. The generation time of the hollow cylindrical electron cloud 60 and the ion cluster 65 is controlled, and the energy of the accelerated ion cluster 65 can be set.

According to the above, the method for instantaneously generating a high-density hollow electron cloud by laser according to the present invention comprises the following steps:

a) projecting laser beams of different wavelengths using two sets of laser devices 20, 30;

b) one set of laser devices 30 projecting the laser beam 35 to the centrally located very small size ion target source 40 to instantaneously generate ion clusters 65;

c) another set of laser devices 20 project a laser beam 25 to an electron generating source that constitutes a concentric circle but surrounds the periphery of the ion target source 40 (in particular, an annular optical cathode 50 is used) to instantaneously generate a hollow or hollow cylinder An electron cloud 60; d) capturing the ion cluster 65 using the hollow or hollow cylindrical electron cloud 60 And enclosed within the hollow or hollow cylindrical electron cloud 60.

The specific method for realizing the hollow or hollow cylindrical electron cloud 60 of the present invention, in addition to the method described above, another method is a hollow static cylindrical electron cloud (hollow) constructed by using electrons and ions concentrically. Beam) A method of generating ion rays. For the outer portion of the concentric circle, the shape of the cathode electrode is formed into a ring shape, and a large current electron beam is extracted by an electrostatic field. A cylindrical electron cloud with a more powerful current can be realized by the Cold Beam synchrotron source (CBS) technology in a state where no ions are generated in the cathode body.

According to the present invention, a doughnut-shaped hollow electron cloud generated by a method of instantaneously generating a high-density hollow electron cloud by laser, for example, a doughnut-shaped hollow electron cloud having a large radius of R and a small radius of a, The number of electrons in the electron bunching is Ne, and the electric field size Emax (or called holding power) in the bubble-shaped hollow electron cloud is calculated as:

Substitute the charge and the value of the induction rate

Taking R = 0.46 cm, a = 0.1 cm, and N = 10 ¹³ as an example, E _max = 1,000 MV/m can be obtained by calculation. This is the electric field corresponding to the electron cloud holding force, indicating the maximum value of the enclosed ion energy. Therefore, the acceleration of the hollow or hollow cylindrical electron cloud 60 in which the ion clusters 65 are contained can be instantaneously accelerated to the speed of light by the magnetic field acceleration of the RF electric field or the electron beam accelerator (ERA).

The device 10 for instantaneously generating a high-density hollow electron cloud by laser has the advantages of accelerating ions at a very short distance, and can realize a more simplified and shortened volume of the accelerator, and can be applied to a human body with high quality of life (Quality Of Life) , QOL) cancer treatment device, for example, can be applied to a desktop type therapeutic accelerator for achieving radiation-resistant tumor treatment (referred to herein as a desktop accelerator size, meaning a radiation irradiation room device that can be placed in an existing hospital) In terms of size).

For example, in the deep body (30 cm or less) of radiation-resistant tumor heavy ion line therapy, the energy of the heavy ion line of each nucleus may be 400 MeV/u or more. Under such conditions, the accelerator designed by the device 10 for generating a high-density hollow electron cloud by laser in the instant of the present invention has a body portion of only 2 m in length, which can still be in the original hospital even after being shielded by enhanced radiation. A heavy ion treatment device having a body portion length of only about 2 m is provided.

Moreover, the heavy ion treatment device with a body portion length of only about 2 m can be designed to have independent slitting and exchange of heavy ion beam and electron beam function, so it can be used as a target irradiation, a strong electron beam X-ray source, and is suitable for cancer. The patient's confirmed position, position monitoring, organ pulsation monitoring, etc., also have three functions of positioning, current simultaneous monitoring and treatment during tumor treatment.

In addition, the heavy ion treatment device having a body portion length of only about 2 m is light in weight and accurate in size, and has a high degree of freedom in rotation on a plane and is easy to rotate. The direction of the heavy ion beam can be emitted in any direction of 360 degrees around the rotary axis, which is different from the case of a circular accelerator such as a synchrotron accelerator and a cyclotron, and does not require a biasing electromagnet or the like, so that the plurality of treatments The room can switch the ray route in a short time, and the ray can also be shared and used in different time periods.

If the accelerator of the heavy ion treatment device is designed as a linear accelerator, the number of times of ion beam emission can be increased, so that the number of ions per pulse is small, and the beam loading is affected by the beam loading. The factors that cause the acceleration of the electric field to be reduced are also reduced.

The above disclosure is a preferred embodiment of the present invention, and the effects achievable with the object of the present invention constitute a so-called equivalent or equal, and can be easily accomplished by those skilled in the art. Any simplifications, modifications, improvements, or variations of the invention may be made without departing from the scope of the claimed invention.

10. . . Device for generating high-density hollow electron cloud instantaneously by laser

20. . . First laser device

25. . . Laser beam

26. . . Central department

30. . . Second laser device

35. . . Laser beam

40. . . Ion target source

50. . . Annular optical cathode

60. . . Hollow electron cloud

65. . . Ion bunch

FIG. 1 is a schematic diagram of a conventional structure of an electron ring accelerator.

2 is a schematic view showing the structure of an apparatus for instantaneously generating a high-density hollow electron cloud by laser.

3 is a schematic diagram of the hollow electron cloud generated by FIG. 2.

10. . . Device for generating high-density hollow electron cloud instantaneously by laser

20. . . First laser device

25. . . Laser beam

26. . . Central department

30. . . Second laser device

35. . . Laser beam

40. . . Ion target source

50. . . Annular optical cathode

60. . . Hollow electron cloud

65. . . Ion bunch

Claims (4)

A device for instantaneously generating a high-density hollow electron cloud by laser, comprising: a first laser device for emitting a laser beam and causing an electron generating source to instantaneously generate an electron cloud; and a second laser device for emitting a laser beam and causing the ion Generating an ion beam cluster instantaneously; a ring-shaped optical cathode receives a laser beam emitted from the first laser device to instantaneously generate a hollow or hollow cylindrical electron cloud; an ion target source is disposed at the ring-shaped optical The center of the cathode forms a concentric circle with the annular optical cathode, and the laser beam emitted by the second laser device instantaneously generates an ion cluster that is trapped and enclosed in the hollow or hollow cylindrical electron cloud. . An apparatus for instantaneously generating a high-density hollow electron cloud by laser according to the first aspect of the invention, wherein the central portion of the laser beam emitted from the first laser device has a light intensity of zero. A method for instantaneously generating a high-density hollow electron cloud by laser, comprising the steps of: a) projecting laser beams of different wavelengths using two sets of laser devices; b) one of the laser devices projecting the laser beam to the centrally located ion The target source is an instantaneously generated ion beam cluster; c) another group of laser devices project a laser beam to a ring-shaped optical cathode that forms a concentric circle but surrounds the periphery of the ion target source to instantaneously generate a hollow or hollow cylindrical shape An electron cloud; d) capturing the ion cluster by the hollow or hollow cylindrical electron cloud and enclosing it within the hollow or hollow cylindrical electron cloud. A method for instantaneously generating a high-density hollow electron cloud by laser, as described in claim 3, wherein the hollow or hollow cylindrical electron cloud containing the ion cluster is subjected to an RF electric field or an electron ring accelerator ( The magnetic field expansion of ERA) accelerates and accelerates the ion cluster.