CN111826609A - A kind of U-W-N ternary film and its preparation method and application - Google Patents

Abstract

A U‑W‑N ternary thin film and a preparation method and application thereof belong to the technical field of laser fusion engineering, and in particular relate to a U‑W‑N ternary thin film with both black cavity dissipation and protection functions and its preparation methods and applications. The purpose of the present invention is to solve the complex structure layer of the existing uranium black cavity, the limited control range of the N content in the UN _x scattering/protective layer, the limited ability to suppress stimulated Brillouin scattering, the M-band hard X-ray of the Au protective layer and the The problem of easy excitation of epithermal electrons. The mass fraction of N in the U‑W‑N ternary film is x%, and 0<x≤66.7, the mass fraction of W is y%, and 0<y≤10%, and the remainder is U. Preparation method: The DC reactive magnetron sputtering co-deposition method is adopted, and N ₂ is used as the reaction gas, and the U-W-N ternary thin film is obtained by magnetron sputtering deposition with a U target and a W target through a DC power supply. The U‑W‑N ternary film was applied to the black cavity as a dispersive/protective layer.

Description

A kind of U-W-N ternary film and its preparation method and application

technical field

The invention belongs to the technical field of laser fusion engineering, and in particular relates to a U-W-N ternary film with black cavity dissipation and protection functions, and a preparation method and application thereof.

Background technique

In order to realize the globally challenging scientific engineering of laser-driven controlled thermonuclear fusion (ICF), people have been looking for black cavity materials with better comprehensive performance of conversion efficiency and radiation field characteristics. Theoretical analysis and experimental research show that compared with the traditional Au black cavity, using metal U with higher radiation and opacity as the cavity wall material of the black cavity can reduce the energy loss by about 17%, and can effectively suppress the M-band hard X. Ray and Epithermal Electron Yield (O. Jones, J. Schein, M. Rosen, et al. Phys. Plasmas, 2007, 14, 056311). However, due to the active chemical properties of U, the United States designed the U black cavity as an "Au-U-Au" sandwich structure, and the inner layer of Au was used to prevent the oxidation of U. In addition, it was found that doping Au in the inner layer of the black cavity with low-Z elements, such as B, forms an Au/B diffusion layer, which helps to suppress the growth of the plasma SBS ejected from the cavity wall (P. Neumayer, RL Berger, D. Callahan, et al.Phys.Plasmas, 2008, 15, 056307), thereby improving the energy utilization efficiency, research shows that the inhibition effect of SBS depends on the doping ratio, and the atomic content of low Z elements is optimized between 20% and 40% inhibitory effect. At present, the basic composition of the high-conversion black cavity in the US National Ignition Program is roughly as follows: Au/B anti-scattering layer-Au inner protective layer-U conversion layer-Au support layer. However, whether it is the Au/B desorption layer or the Au protective layer, the Au element M-band hard X-rays and superheated electrons are easily excited and preferentially penetrate the target pellet, leading to fuel preheating, which makes it impossible to fundamentally solve the problem. A series of problems such as mixing caused by heat. Chinese scientists first proposed to use 100-nanometer-thick UN as the protective layer in the U black cavity, eliminating the influence of Au element M-band hard X-rays and epithermal electrons, due to the infiltration of low-Z N element, and taking into account the growth of SBS. Comprehensive performance of inhibition and anti-oxidation of U layer (Liang Guo, YongkunDing, PifengXing, etal. New J. Phys, 2015, 17, 113004). However, since the stable chemical formulas of the U and N binary system are UN, U ₂ N ₃ and UN ₂ , the adjustment range of the atomic content of N is limited between 50% and 66.7%, otherwise, the excess metal U phase in the film will Will cause the film to oxidize in air. The N doping ratio in this range cannot achieve the best effect of suppressing the growth of SBS.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the complex structure layer of the existing uranium black cavity, the limited control range of the N content in the UN _x scattering/protective layer, the limited ability to suppress stimulated Brillouin scattering, the M-band hard X-ray of the Au protective layer and the A UWN ternary thin film and a preparation method and application thereof are provided in order to solve the problem of easy excitation of epithermal electrons.

A U-W-N ternary film, the mass fraction of N in the U-W-N ternary film is x%, and 0<x≤66.7, the mass fraction of W is y%, and 0<y≤10%, the remainder is U, and U-W-N three The thickness of the thin film is 100 nm to 700 nm.

A method for preparing a UWN ternary thin film is specifically completed according to the following steps: adopting a DC reactive magnetron sputtering co-deposition method, using Ar as a protective gas, using _N2 as a reaction gas, using a U target and a W target to pass a direct current Magnetron sputtering deposition with power supply to obtain UWN ternary thin film, the purity of the U target> 99%, the purity of the W target> 99.99%, the purity of the Ar> 99.9999%, the purity of the N ₂ > 99.9999%. An application of a UWN ternary film as an anti-scattering/protective layer on a black cavity.

An application of a U-W-N ternary film as a dispersive/protective layer on a black cavity.

Advantages of the present invention: 1. By adjusting the ratio of the gas flow of argon to the gas flow of nitrogen, the content of N atoms in the U-W-N ternary film can be regulated within a wide range of (0, 66.7%), and finally the optimal SBS suppression can be achieved Second, a small amount of high-Z alloy element W is added to the U-W-N ternary film, which improves the chemical stability of the film. Third, in order to improve the laser-cavity target coupling efficiency, high-Z materials are usually selected as the black cavity, which is relatively For the black cavity wall material Au, the atomic number of the U element is larger, the conversion efficiency of laser X-rays is higher, and it has a lower proportion of M-band hard X-rays and super-hot electron yield; 4. When U-W-N When the ternary film is used as a dispersive/protective layer on the black cavity, due to the stable chemical properties of the U-W-N ternary film, ①. The U-W-N ternary film can suppress SBS and also prevent the oxidation failure of the internal U conversion layer. 2. The uranium black cavity is the main trend of the current development of the ignition black cavity. The U-W-N ternary film of the present invention and the U conversion layer are diffused by atomic gradient to form better interface bonding force and chemical phase. Therefore, when the U-W-N ternary film is applied to the black cavity as a scattering/protective layer, it can optimize the SBS suppression effect, suppress the M-band hard X-ray and super hot electron yield, improve the laser X-ray conversion efficiency, and protect the uranium The role of the black cavity conversion layer can be used to replace the black cavity UN dissipation/protection layer and the Au protective layer.

Detailed ways

Embodiment 1: This embodiment is a U-W-N ternary film, which is characterized in that the mass fraction of N in the U-W-N ternary film is x%, and 0<x≤66.7, and the mass fraction of W is y%, and 0< y≤10%, the remainder is U, and the thickness of the U-W-N ternary film is 100nm-700nm.

Specific embodiment 2: This embodiment is a preparation method of a UWN ternary film, which is specifically completed according to the following steps: using a DC reactive magnetron sputtering co _- deposition method, using Ar as the protective gas, and using N as the reactive gas , use U target and W target to conduct magnetron sputtering deposition through DC power supply to obtain UWN ternary thin film, the purity of the U target> 99%, the purity of the W target> 99.99%, the purity of the Ar> 99.9999 %, the purity of the N ₂ is >99.9999%.

Embodiment 3: The difference between this embodiment and Embodiment 2 is that the specific process of the DC reactive magnetron sputtering co-deposition method is as follows:

1. Install 1 to 9 mandrels on the rotating support table, adjust the distance between the U target and the center of the mandrel to be 10cm to 20cm, and the normal line of the center of the U target and the plane of the mandrel form an included angle of 45°; adjust the W target and the center of the mandrel. The distance between the center of the mandrel is 10cm to 20cm, and the normal line of the center of the W target surface and the plane where the mandrel is located forms an included angle of 45°; the normal lines of the U target and the W target and the plane where the mandrel is located are symmetrically distributed;

2. The vacuum degree of the deposition chamber can reach 1×10 ^-8 Pa～1×10 ^-6 Pa by mechanical pump and molecular pump, and then filled with protective gas and reactive gas, the gas flow of protective gas and the gas of reactive gas The flow ratio is 20:(1～5), and the gate valve is adjusted to maintain the vacuum degree of the deposition chamber at 0.1Pa～1Pa;

3. Use the ion beam to etch the surface of the mandrel for 3min-20min, and during the etching process, the rotating support table rotates at a speed of 1rpm-30rpm;

4. There are baffle plates between the U target and the mandrel and between the W target and the mandrel, and the pre-sputtering is carried out for 10min under the DC power of the U target and the DC power of 20W to 400W and the DC power of the W target of 20W to 400W. ~20min;

5. Open the baffles between the U target and the mandrel and between the W target and the mandrel, deposit the DC power of the U target at 20W-400W and the DC power of the W target at 20W-400W, and deposit to the U-W-N ternary The thickness of the film is 100nm-700nm, and the rotating support table rotates at a speed of 1rpm-30rpm during the deposition process, that is, the U-W-N ternary film is prepared on the surface of the mandrel by the DC reactive magnetron sputtering co-deposition method.

Others are the same as in the second embodiment.

Embodiment 4: The difference between this embodiment and Embodiment 3 is that the gas flow rate of argon in step 2 is 20 sccm. Others are the same as the third embodiment.

Embodiment 5: The difference between this embodiment and Embodiment 3 or 4 is that: in step 3, the surface of the mandrel is etched by ion beam for 3 min under the condition that the ion energy is 50eV～500eV and the ion beam current is 5mA～100mA ~20min. Others are the same as the third or fourth embodiment.

Embodiment 6: This embodiment is an application of a U-W-N ternary thin film, which is applied to a black cavity as an anti-scattering/protective layer.

The following experiments are used to verify the effect of the present invention

Embodiment 1: a kind of preparation method of U-W-N ternary film, is specifically completed according to the following steps:

1. Install the 9 mandrels on the rotating support table, adjust the distance between the U target and the center of the mandrel to 15cm, and the normal line of the U target center and the plane of the mandrel at a 45° angle; adjust the distance between the W target and the center of the mandrel It is 15cm, and the normal line of the center of the W target surface and the plane where the mandrel is located forms an included angle of 45°; the normal lines of the U target and W target and the plane where the mandrel is located are symmetrically distributed;

2. Evacuate the deposition chamber by mechanical pump and molecular pump to make the vacuum degree of the deposition chamber reach 5×10 ^-8 Pa, and then fill with protective gas and reaction gas. The protective gas is argon, the reaction gas is nitrogen, and the gas flow of argon is 20sccm, the gas flow of nitrogen is 2sccm, and the gate valve is adjusted to maintain the vacuum degree of the deposition chamber at 0.7Pa;

3. Use the ion beam to etch the surface of the mandrel for 15min under the ion energy of 250eV and the ion beam current of 10mA, and the rotating support table rotates at a speed of 15rpm during the etching process;

4. There are baffle plates between the U target and the mandrel and between the W target and the mandrel, and the pre-sputtering is performed for 15 minutes under the DC power of the U target and the DC power of the W target of 160W and 40W;

5. Open the baffles between the U target and the mandrel and between the W target and the mandrel, and deposit for 90 minutes under the DC power of the U target and the W target at 160W and 40W. Rotating at 15 rpm, the U-W-N ternary thin film was prepared on the surface of the mandrel by the DC reactive magnetron sputtering co-deposition method.

The UWN ternary film obtained in Example 1 was measured using an Auger electron spectrometer, and it was known that the atomic ratio of U:W:N in the UWN ternary film obtained in Example 1 was 10:1:4, and the UWN ternary film was 10:1:4. The thickness of the film is about 400nm; therefore, the atomic percentage of N in the UWN ternary film obtained in Example 1 is 26.67%, which breaks through the control range of 50% to 66.7% of the atomic content of N in the existing _UNx dispersion layer.

Embodiment 2: an application of a UWN ternary film, the UWN ternary film is applied to the black cavity as the anti-scattering/protective layer in place of the UN _x anti-scattering/protective layer and the Au protective layer, to obtain the UWN ternary thin-film uranium black cavity; The UWN ternary film was prepared by Example 1.

The lifetime of UWN ternary thin film uranium black cavity was characterized _by Auger electron spectrometer. cavity with a lifespan of 7 days.

Claims (6)

1. The U-W-N ternary film is characterized in that the mass fraction of N in the U-W-N ternary film is x percent, x is more than 0 and less than or equal to 66.7, the mass fraction of W is y percent, y is more than 0 and less than or equal to 10 percent, the balance is U, and the thickness of the U-W-N ternary film is 100 nm-700 nm.

2. The method for preparing a U-W-N ternary film according to claim 1, wherein the preparation method of a U-W-N ternary film is performed by the following steps: adopting a direct-current reaction magnetron sputtering codeposition method, using Ar as a protective gas and N₂Performing magnetron sputtering deposition on a U target and a W target through a direct current power supply as reaction gas to obtain a U-W-N ternary film, wherein the purity of the U target is more than 99 percent, the purity of the W target is more than 99.99 percent, the purity of Ar is more than 99.9999 percent, and the purity of N is more than 99 percent₂The purity of (A) is more than 99.9999%.

3. The method for preparing the U-W-N ternary film according to claim 2, wherein the specific process of the direct current reactive magnetron sputtering codeposition method is as follows:

firstly, mounting 1-9 mandrels on a rotary support table, adjusting the distance between a U target and the center of the mandrel to be 10-20 cm, and forming an included angle of 45 degrees between the normal line of the center of the U target and the plane of the mandrel; adjusting the distance between the W target and the center of the mandrel to be 10-20 cm, wherein the central normal of the surface of the W target forms an included angle of 45 degrees with the plane of the mandrel; the U target and the W target are symmetrically distributed with the normal of the plane of the mandrel;

secondly, the vacuum degree of the deposition chamber reaches 1 x 10 by using a mechanical pump and molecular pump to pump vacuum^-8Pa～1×10^-6Pa, then filling protective gas and reaction gas, wherein the gas flow ratio of the protective gas to the reaction gas is 20 (1-5), and adjusting a gate valve to maintain the vacuum degree of the deposition chamber at 0.1 Pa-1 Pa;

etching the surface of the mandrel for 3-20 min by utilizing ion beams, and rotating the support table at the rotating speed of 1-30 rpm in the etching process;

fourthly, baffles are respectively arranged between the U target and the mandrel and between the W target and the mandrel, and pre-sputtering is carried out for 10-20 min under the condition that the power of the U target direct current power supply is 20-400W and the power of the W target direct current power supply is 20-400W;

fifthly, opening baffles between the U target and the mandrel and between the W target and the mandrel, depositing until the thickness of the U-W-N ternary film is 100 nm-700 nm when the power of the U target direct current power supply is 20W-400W and the power of the W target direct current power supply is 20W-400W, and rotating the rotary support table at the rotating speed of 1 rpm-30 rpm in the deposition process to finish the preparation of the U-W-N ternary film on the surface of the mandrel by using a direct-current reactive magnetron sputtering codeposition method.

4. The method according to claim 3, wherein the flow rate of the shielding gas in step two is 20 sccm.

5. The method for preparing a U-W-N ternary film according to claim 3, wherein in the third step, the surface of the mandrel is etched by using an ion beam for 3min to 20min under the conditions that the ion energy is 50eV to 500eV and the ion beam current is 5mA to 100 mA.

6. The use of a ternary U-W-N film according to claim 1, wherein the ternary U-W-N film is used as a diffusion/shielding layer on a black cavity.