CN104713859A - Method for measuring HF high-vibration-state particle number distribution by using low-resolution near-infrared fluorescence spectrum - Google Patents

Abstract

The present invention relates to a technology for measuring HF high-vibration-state particle number distribution by using low-resolution near-infrared fluorescence spectrum, wherein the technology is based on the spontaneous radiation fluorescence spectrum technology, and is a new method for measuring the HF molecule high vibration excitation state energy level particle number distribution. According to the present invention, the method is mainly applied in the technical field of chemical laser test diagnosis, and is produced for simplification of the vibration excitation state particle number distribution measurement in the HF chemical laser system; with the method of the present invention, only the intensities of a plurality of P branch spectrum lines of the HF fundamental frequency spontaneous radiation fluorescence spectrum are subjected to simple adding, and characteristics of simpleness, convenience, high precision, non-invasion and the like are provided; and with the method of the present invention, the rapid measurement on various energy levels of the high vibration excitation state particle number distributions in the HF chemical laser can be achieved.

Description

A kind of method utilizing low resolution near-infrared fluorescent spectral measurement HF high vibrational state population to distribute

Technical field

The present invention relates to a kind of optical cavity measuring method of chemical HF laser instrument.The method utilizing low resolution near-infrared fluorescent spectral measurement HF high vibrational state population to distribute, may be used for the population distribution situation of monitoring HF vibration excited state molecule, thus understands the behavior in service of HF chemical laser.

General high vibrational state HF molecule mainly comes from H atom and F ₂the chemical reaction (the vibrational quantum number v of excited state product HF is the highest can reach 9) of molecule, and this reaction is for strong exothermic process, can cause that the temperature of optical cavity raises, thermal chokes and small-signal gain reduction.When combustion chamber burner exit exists a large amount of F ₂time, often cause thermal response (H+F ₂) occur in a large number.

Therefore, by observing luminous intensity and the population distribution situation of high vibrational state HF molecule, F in the combustion chamber burner product of HF laser instrument can be understood ₂account for how much number percent and optical cavity temperature whether can raise and cause thermal chokes etc., that is can recognize firing chamber ruuning situation and the optical cavity ruuning situation of HF chemical laser, thus predict its performance.

Background technology

Since First chemical laser in 1964 comes out, the development of chemical laser can be rated as advances by leaps and bounds, speed is surprising, wherein especially ripe with the development of HF chemical laser, continuous wave output power had once been once the synonym of laser weapon up to the U.S. Alpha HF chemical laser of MW rank.

The main operating principle of HF chemical laser is as follows:

(1) containing F compound pyrolysis generation F atom in a combustion chamber, also a small amount of F may be had ₂molecule, in addition, in the process passing through nozzle, F atom also compound may produce F ₂molecule;

(2) F atom out and the H added from nozzle ₂molecule reacts, and produces the HF molecule (representing with HF (v)) of vibration excited state, F+H ₂→ HF (v)+H, the thermal discharge less (31.5kcal/mol) of this reaction, be called as cold reaction, the vibrational quantum number of product HF molecule is the highest can arrive v=3;

(3) H atom produced again can with F ₂there is cold reaction in molecule, produces the HF molecule (representing with HF (v)) of vibration excited state, H+F ₂→ HF (v)+F, the thermal value very large (98.0kcal/mol) of this reaction, be called as thermal response, the vibrational quantum number of product HF molecule is the highest can arrive v=9;

(4) according to einstein's stimulated radiation principle, there is resonance in vibration excited state molecule HF (v) in optical cavity, produces laser.

According to the computing formula of the small-signal gain of HF chemical laser, when temperature is higher, small-signal gain also can reduce thereupon, is unfavorable for the running of HF chemical laser.Therefore many times we do not wish that the optical cavity temperature of HF chemical laser is too high, and that is we do not wish that too much thermal response occurs, so F in jet expansion air-flow ₂molecule content is more few better.

Because cold reaction can only by the vibrational energy level of HF molecule maximum pump Pu to v=3, if so observe the radiation of HF (v=4,5,6,7 etc.) high vibrational energy level, then show there occurs more H+F2 thermal response.That is, according to the population distribution situation of high vibrational energy level, we can obtain the relative content of F2 in combustor product, recognize the operation conditions of firing chamber.So the high vibrational state population distribution situation in measurement optical cavity is very useful.

HF fundamental radiation (Δ v=1) is positioned at middle infrared, can measure with Fourier spectrometer, but due to the restriction of response sensitivity, the fundamental radiation of the high vibrational energy level of v>=4 is very weak, Fourier spectrometer measure less than, so be not suitable for.

The general radio-frequency radiation of HF first (Δ v=2) is positioned at near-infrared region, can measure with near infrared spectrometer OMA-V etc., and response sensitivity is also good, but unfortunately this region has the strong absorption band (near 1.4um) of a steam just, can measurement effect be had a strong impact on, therefore also be not suitable for.

The general radio-frequency radiation of HF second (Δ v=3) is positioned at the shorter near-infrared region of wavelength, also can measure with near infrared spectrometer OMA-V etc., and this region does not have strong absorption band, therefore be applicable to measuring the high vibrational state population distribution situation in optical cavity, this is the present invention's radiation band series that will adopt just also.What uniquely can consider is that part P props up spectrum may prop up spectra overlapping with other R, and for this problem, we solve when spectrometer lack of resolution time.

The present invention just in this context, fully takes into account the characteristic of each radiation bands of a spectrum of HF and a kind of technology measuring high vibrational state population distribution situation in optical cavity designed.The ultimate principle of this technology is as follows:

According to particle luminous intensity formula I=h ν AN, when wave number change is little, can obtain population N ∝ I/A, wherein A is Einstein Spontaneous Emission Coefficients.

Summary of the invention

The object of this invention is to provide a kind of technology utilizing low resolution near-infrared fluorescent spectral measurement HF high vibrational state population to distribute.By this kind of technology, realize measuring the distribution of HF high vibrational state population, and then investigate the object of HF laser instrument firing chamber and optical cavity operation conditions.

The application gives a kind of method utilizing low resolution fluorescence spectral measuring HF high vibrational state population to distribute, and comprises near infrared spectrometer, coupled fiber, signals collecting computing machine, shaking turns line strength reading, data processing technique;

Wherein, near infrared spectrometer is for gathering HF high vibrational state spontaneous radiation fluorescence spectrum.

Wherein, coupled fiber is used for the fluorescent radiation of laser instrument to be transferred near infrared spectrometer, and it is even at the wavelength response degree of near-infrared region.

Wherein, signals collecting computing machine for handling spectrometer collection, and carries out data processing.

Wherein, shaking turns line strength and reads and have employed peak height and replace peak area, and only reads each and shake and turn P1-P6 six spectral lines that bands of a spectrum P props up.

Wherein, data processing technique refers to, when processing data, first by (3-0,4-1,5-2,6-3, certain P1-P6 line strength turning bands of a spectrum of shaking 7-4) sums up, and then divided by the Einstein coefficient of this vibrational state, can obtain the relative population of this vibrational energy level.

For realizing object of the present invention, concrete technical scheme as shown in Figure 1:

First provide fibre-optic transmission system (FOTS) to correct the response coefficient of wavelength, then Optical Fiber Transmission coupled system is utilized to be coupled into by the fluorescence that HF chemical laser experimental provision sends, near infrared spectrometer, near infrared spectrometer is utilized to measure HF second general radio-frequency radiation (Δ v=3) spectrum, according to the spectrometer detection system completed in advance, the response coefficient of wavelength is corrected again, high vibrational state HF population distribution situation can be obtained by survey calculation.

During experiment, open slide valve, vacuumize, do not go out to swash to penetrate the HF chemical laser experiment of light, what at this moment send from HF chemical laser experimental provision only has spontaneous radiation luminous; Utilize near infrared spectrometer to measure near infrared spectrum, centre wavelength is set to 990nm.All air inlets, to find time and isolating valve solenoid valve, and be wired to computing machine and realize Long-distance Control.Pressure, temperature and other test parameters are input to computer recording and monitoring equally.

The invention has the beneficial effects as follows:

1, the present invention measures HF second general radio-frequency radiation (Δ v=3) spectrum by adopting near infrared spectrometer OMA-V, and final measurement obtains the distribution of HF high vibrational state population.Avoid the difficult problem that high vibrational state HF fundamental radiation intensity is more weak, be difficult to measurement, and high vibrational state HF first general radio-frequency radiation bands of a spectrum there is a difficult problem for strong absorption band.Successfully measure the high vibrational state population distribution situation of v>=4, and contrast with the population of HF (v=3);

2, the present invention only reads 6 spectral lines such as the P1-P6 of each vibrational band, thus under avoiding near infrared spectrometer OMA-V low resolution condition, the R of HF vibration rotation spectrum bands of a spectrum props up the problem of propping up overlap with a part of P.

Accompanying drawing explanation

Fig. 1 is operating process schematic diagram of the present invention.

Wherein, 1-HF chemical laser experimental provision; 2-Optical Fiber Transmission coupled system; 3-near infrared spectrometer; 4-fibre-optic transmission system (FOTS) corrects the response coefficient of wavelength; 5-spectrometer detection system corrects the response coefficient of wavelength; The general frequency emission spectrum of 6-HF second; 7-survey calculation obtains high vibrational state HF population distribution situation.

Fig. 2 is the general radio-frequency radiation of HF second (Δ v=3) spectrum gathered in embodiments of the invention.Can see, prop up spectral line with next vibrational state R overlap because P (7) and above P props up spectral line, so cannot differentiate, 6 P such as P1-P6 can only be separated and prop up spectral line; Here it is, and foregoing R props up spectral line and P props up the partly overlapping low resolution situation of spectral line.

Embodiment

Embodiment 1

Once utilize the example that low resolution near-infrared fluorescent spectral measurement HF high vibrational state population distributes.

As shown in Figure 1, concrete operation step is as follows:

Prepare before experiment:

The wavelength response degree of the first step to the coupling fiber transmission system 2 of transmission near infrared light carries out response coefficient and corrects 4.

The wavelength response degree of second step near infrared spectrometer OMA-V carries out response coefficient and corrects 5.

The centre wavelength of near infrared spectrometer OMA-V is set to 990nm by the 3rd step, arranges suitable slit width and time shutter in addition, guarantees that spectral intensity is maximum but can not supersaturation.

Experimentation:

4th step checks HF chemical laser experimental provision 1, opens slide valve, vacuumizes, and does not go out to swash to penetrate the HF chemical laser experiment of light, namely only carries out combustion chemistry reaction, send fluorescent radiation; But there is no chamber mirror, there will not be laser.

5th step gathers HF second general radio-frequency radiation (Δ v=3) spectrum 6, and carries out responsiveness correction to the result obtained, and obtains the spectrogram after correcting.

Experimental result:

The P1-P6 spectral line of the vibrational transition bands of a spectrum such as (3-0), (4-1), (5-2), (6-3), (7-4) of HF is separated by the 6th step, and read its height of spectral line, result is as follows:

Wherein, P _3-0the P1 spectral line of 1 expression (3-0) bands of a spectrum, other by that analogy.

The rotational line intensity of above-mentioned each bands of a spectrum sums up by the 7th step, using the luminous intensity I of summed result as each vibrational band _v.Again by I _vdivided by Einstein Spontaneous Emission Coefficients A _v, the population N being equal to v vibrational state can be similar to _v.Again Nx is normalized (making the population of v=3 be 1), the relative percentage f of each high vibrational energy level population of HF can be obtained _v.Result is as follows:

Shake and turn bands of a spectrum	A v	Ix	N v	f v
					3-0	1.5	7170	4780	1.0000
4-1	5.5	5245	953.6364	0.1995
					5-2	13.1	4255	324.8092	0.0679
6-3	25.4	3536	139.2126	0.0291
					7-4	44.9	2468	54.9666	0.0115

8th step calculates the distribution of high vibrational state HF population, and provide v=3,4,5,6, the population of 7 each vibrational state is distributed as: N _v=3: N _v=4: N _v=5: N _v=6: N _v=7=1:0.1995:0.0679:0.0291:0.0115.

Claims (2)

1. the method utilizing low resolution near-infrared fluorescent spectral measurement HF high vibrational state population to distribute, is characterized in that:

(1) utilize near infrared spectrometer to record HF high vibrational state spontaneous radiation fluorescence spectrum, obtain HF high vibrational state v=3,4,5, the population distribution situation of 6,7;

(2) only need to read each to shake and turn P1-P6 six spectral lines that bands of a spectrum P props up, applicable R prop up spectral line with

P props up the partly overlapping low resolution situation of spectral line.

2., according to the method utilizing low resolution fluorescence spectral measuring HF high vibrational state population to distribute according to claim 1, comprise near infrared spectrometer, coupled fiber, signals collecting computing machine, shaking turn line strength reading, data processing technique, it is characterized in that:

Wherein, near infrared spectrometer is for gathering HF high vibrational state spontaneous radiation fluorescence spectrum;

Wherein, coupled fiber is used for the fluorescent radiation of laser instrument to be transferred near infrared spectrometer, and it is even at the wavelength response degree of near-infrared region;

Wherein, signals collecting computing machine for handling spectrometer collection, and carries out data processing;

Wherein, shaking turns line strength and reads and have employed peak height and replace peak area, and only reads each and shake and turn P1-P6 six spectral lines that bands of a spectrum P props up;

Wherein, data processing technique refers to, when processing data, first by (3-0,4-1,5-2,6-3, certain P1-P6 line strength turning bands of a spectrum of shaking 7-4) sums up, and then divided by the Einstein coefficient of this vibrational state, can obtain the relative population of this vibrational energy level.