CN101282612A - Method for laser accelerating ion - Google Patents

Abstract

The invention provides a method of laser ion acceleration, belonging to the technical field of ion acceleration. The method of laser ion acceleration includes: adopting circularly polarized lasers to bombard a monolayer target which is a film containing ions to be accelerated; or adopting circularly polarized lasers to bombard high-density gas containing ions to be accelerated which is ejected out through a nozzle. The invention can greatly improve the accelerating gradient and accelerating length of irons, and meanwhile the quality of beam obtained by the acceleration can compare to common radio frequency accelerators.

Description

A kind of method of laser accelerated ions

Technical field

The present invention relates to ion speed technology field, relate in particular to a kind of laser that adopts and realize the method that ion quickens.

Background technology

Conventional ion quickens to adopt the radio-frequency accelerator technology to realize usually.Yet the ion acceleration equipment based on radio-frequency accelerator is bulky, involve great expense, maintenance and operating cost are high.The cost of the large-scale ion acceleration equipments such as HIMAC of German GSI that has put into operation now and Japan is about about 1,000,000,000 Euros, the nearly thing in China Lanzhou the heavy ion avcceleration cost also more than several hundred million RMB.Utilize the electromagnetic field of ultra-intense laser to come speeding-up ion, can improve the accelerating gradient of ion greatly.The existing method that adopts laser to realize speeding-up ion adopts linearly polarized laser usually $(E=E_L\left(x\right)\sin \left({\mathrm{\ω}}_{L}t\right)\hat{y})$ And adopt double-deck solid target, be that ground floor is the heavy metal target of several micron thickness, the second layer is organic adhesion layer of hydrogeneous or other light elements, and the electronics of getting from metallic target can quicken the hydrogen ion in the second layer or other is than light element, wherein, the energy of laser will be mainly used in electrons heat, consequent accelerating field intensity is limited, thereby the ion energy that obtains is restricted, and quality of beam is poor.At present, with the power level and the technology of existing ultra-intense laser, the ion energy that acceleration obtains is low, line can loose greatly, and beam flux is low.

Summary of the invention

The object of the present invention is to provide a kind of method of laser accelerated ions, reduce line significantly and can loose, improve the quality of ion beam.

Above-mentioned purpose of the present invention is achieved by the following technical solutions:

A kind of method of laser accelerated ions, its step comprises: adopt circularly polarized laser bombardment single shell target, described single shell target is to contain to remain the film of speeding-up ion.

The range of light intensity of described laser is 10 ¹⁸～10 ²²W/cm ²

The thickness of described single shell target is 0.001 micron～10 microns.

The described speeding-up ion for the treatment of is a protium, comprises deuterium, tritium isotope, and described single shell target is the organic film that contains protium.

The described speeding-up ion for the treatment of is a carbon, and described single shell target is the carbon film.

The described speeding-up ion for the treatment of is a metallic element, and described single shell target is and treats speeding-up ion corresponding metal film.

Described single shell target is placed in the middle of the vacuum.

A kind of method of laser accelerated ions, its step comprises: adopt circularly polarized laser, the bombardment nozzle ejection goes out contains and remains the high density gas of speeding-up ion (gas density is greater than critical density n _r=1*10 ²¹Individual/cm ³).

The electronics normalization density n of described high density gas _e/ n _r＞1.

The present invention has the advantage of the following aspects:

The present invention adopts circularly polarized laser, and electronics can pass to laser energy the ion in the target or in the gas effectively, avoids laser energy mainly to be converted into the heat energy of electronics, but energy is more effectively passed to ion.When circularly polarized laser bombardment single shell target, the electronics in the target will be promoted and be compressed in the thin layer by optical pressure integral body, electric field pulling that this moment, separation of charge produced and the ion in the acceleration target.In this push-and-pull accelerator, ion can obtain quickening and pack simultaneously, thereby has very low loosing.The present invention uses the Dynamics Optimization method of (as rfq accelerator) in the radio frequency linear accelerator, can improve accelerating gradient and effective accelerating length of ion greatly, and the quality of beam that quickens simultaneously to obtain can be comparable with conventional radio-frequency accelerator.This will reduce the cost and the operation and maintenance cost of ion acceleration equipment greatly.

Description of drawings

Below in conjunction with accompanying drawing the present invention is illustrated in further detail:

The electric field that Fig. 1 circularly polarized light (circular polarization) and linearly polarized light (linearpolarization) produce in plasma;

The schematic diagram of the double-deck target of Fig. 2 a prior art; The schematic diagram of Fig. 2 b single shell target; Wherein, 1 is heavy metal target, and 2 for containing the single shell target of waiting to quicken element;

The ion power spectrum that Fig. 3 and Fig. 4 obtain for the present invention's acceleration.

Embodiment

Below with reference to accompanying drawing of the present invention, more detailed description goes out most preferred embodiment of the present invention.

With reference to figure 1, adopt circularly polarized laser, its electric field can be expressed as $E=E_L\left(x\right)(\sin \left({\mathrm{\ω}}_{L}t\right)\hat{y}+\cos \left({\mathrm{\ω}}_{L}t\right)\hat{z}).$ (electron density n when circularly polarized laser is transmitted on the high density target _eGreater than plasma critical density n _r), laser can not see through target body, but continue to reflect.This moment laser optical pressure with the reduced overall electronics, thereby electronics can be directly passes to ion in the target with the optical pressure of laser.If employing linearly polarized laser $(E=E_L\left(x\right)\sin \left({\mathrm{\ω}}_{L}t\right)\hat{y}),$ The laser part energy will be mainly used in electrons heat, and the electric field that is used for speeding-up ion will be far smaller than the electric field that circularly polarized laser produces, thus the finite energy that ion obtains, and also quality of beam is poor.

The present invention adopts the laser bombardment single shell target, with reference to figure 2, single shell target waits to quicken the element film for containing, and the electronics in this single shell target can retrain the ion in the target, simultaneously pressure of laser light is passed to ion effectively, thereby produce low-energy-spread and high-quality high energy ion beam.

A) if the acceleration hydrogen ion as long as adopt the film target that contains protium, perhaps adopts gas nozzle to spray the gas that high density contains protium.Target thickness is less than 10 microns.

B) if quicken other element (as carbon, metal), employing carbon elements, the single shell target of metallic element (target thickness is less than 10 microns).

The embodiment of the invention one:

Superpower circularly polarized laser (light intensity I=6.9*10 ¹⁹W/cm ²), the hydrogeneous high-density film target of individual layer (n _e/ n _r=10), thickness is 0.2 micron, and laser pulse length is 330fs.The energy efficient of laser is converted into hydrionic energy under this accelerated method, and this energy is more than the 300MeV, and quality of beam is good, and can loose is lower than 4%, as shown in Figure 3.

The embodiment of the invention two:

Superpower circularly polarized laser (light intensity I=2.8*10 ²⁰W/cm ²), solid target is metal copper film (n _e/ n _r≈ 100), thickness is 0.05 micron, laser pulse length is 330fs.The energy efficient of laser is converted into the energy of copper ion under this accelerated method, and this energy is more than the 133MeV, and quality of beam is good, and can loose is lower than 4%.

The embodiment of the invention three:

Superpower circularly polarized laser (light intensity I=4.4*10 ¹⁹W/cm ²), adopt gas nozzle to spray the gas (n that high density contains protium _e/ n _r=3), laser pulse length is 330fs.The hydrogen ion energy is more than the 120MeV under this accelerated method, and line can loose and be lower than 4%, as shown in Figure 4.

The foregoing description is of the present invention giving an example, although disclose most preferred embodiment of the present invention and accompanying drawing for the purpose of illustration, but it will be appreciated by those skilled in the art that: without departing from the spirit and scope of the invention and the appended claims, various replacements, variation and modification all are possible.Therefore, the present invention should not be limited to most preferred embodiment and the disclosed content of accompanying drawing.

Claims (9)

1. the method for a laser accelerated ions, its step comprises: adopt circularly polarized laser bombardment single shell target, described single shell target is to contain to remain the film of speeding-up ion.

2. the method for laser accelerated ions as claimed in claim 1, it is characterized in that: the scope of the light intensity of described laser is 10 ¹⁸W/cm ²～10 ²²W/cm ²

3. the method for laser accelerated ions as claimed in claim 1, it is characterized in that: the thickness of described single shell target is 0.001 micron～10 microns.

4. as the method for claim 1 or 3 described laser accelerated ions, it is characterized in that: the described speeding-up ion for the treatment of is a protium, comprises deuterium, tritium isotope, and described single shell target is the organic film that contains protium.

5. as the method for claim 1 or 3 described laser accelerated ions, it is characterized in that: the described speeding-up ion for the treatment of is a carbon, and described single shell target is the carbon film.

6. as the method for claim 1 or 3 described laser accelerated ions, it is characterized in that: the described speeding-up ion for the treatment of is a metallic element, and described single shell target is and treats speeding-up ion corresponding metal film.

7. the method for laser accelerated ions as claimed in claim 1, it is characterized in that: described single shell target is placed in the middle of the vacuum.

8. the method for a laser accelerated ions, its step comprises: adopt the gas for the treatment of speeding-up ion that contains that circularly polarized laser bombardment nozzle ejection goes out, described gas density is greater than critical density n _r=1*10 ²¹Individual/cm ³

9. the method for laser accelerated ions as claimed in claim 8 is characterized in that: the normalization density n of described gas _e/ n _r＞1.

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