CN103398818A - Simple method and device measuring vacuum pressure of cold-atom experimental system - Google Patents
Simple method and device measuring vacuum pressure of cold-atom experimental system Download PDFInfo
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- CN103398818A CN103398818A CN2013102411761A CN201310241176A CN103398818A CN 103398818 A CN103398818 A CN 103398818A CN 2013102411761 A CN2013102411761 A CN 2013102411761A CN 201310241176 A CN201310241176 A CN 201310241176A CN 103398818 A CN103398818 A CN 103398818A
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Abstract
The invention relates to vacuum pressure measuring technology of cold-atom experimental systems, in particular to a simple method and a device measuring the vacuum pressure of a cold-atom experimental system. The invention solves the problems that a prior vacuum pressure measuring technology for the cold-atom experimental system is large in energy consumption in the measuring process, and measuring instruments need to occupy certain space. The simple method is comprises the steps that a) load curves of different capture optical powers of the cold-atom experimental system under the same vacuum pressure are measured; b) linearity fitting is carried out on atom loss coefficients of the different capture optical powers of the cold-atom experimental system under the same vacuum pressure; and c) according to the loss efficient caused by collision between atoms and background gas in the cold-atom experimental system, the vacuum pressure of the cold-atom experimental system is calculated. The simple method and device are suitable for measuring the vacuum pressure of the cold-atom experimental system.
Description
Technical field
The present invention relates to the vacuum pressure measuring technique of cold atom experimental system, specifically a kind of straightforward procedure and device of measuring cold atom experimental system vacuum pressure.
Background technology
Based on the cold atom experimental system of vacuum system, be widely used in the precision measurement of the research of the basic subjects such as quantum mechanics, atomic and molecular physics and some physics constant.In actual applications, in order to obtain and keep the vacuum tightness of cold atom experimental system, need to measure the vacuum pressure of cold atom experimental system.Under the prior art condition, the vacuum pressure measurement of cold atom experimental system is to realize by special vacuum measurement instrument (for example ion gauge, residual gas analyzer, ionic pump), not only cause thus in measuring process energy consumption large, and cause surveying instrument need to take the certain space volume.Particularly, the power of ion gauge usually in about 100W, volume usually more than 100cm3, thereby in its measuring process, energy consumption is large, spatial volume is large.The power of residual gas analyzer and volume are equally very large.The leakage current of ionic pump can limit reading of minimum vacuum degree, and the relation between its working current and vacuum pressure can be different and change along with the design of ionic pump, thereby in its measuring process, not only energy consumption is large, space hold is many, and the process complexity.The volume of above-mentioned vacuum measurement instrument and power consumption are in the scientific experiment chamber can be uncared-for, but pursue to oversimplify and the business machine of efficient activity, and some special be but experimentally unacceptable.Based on this, be necessary to invent a kind of vacuum pressure measuring technique of brand-new cold atom experimental system, large and surveying instrument need to take the problem of certain space volume with energy consumption in the vacuum pressure measuring technique measuring process that solves existing cold atom experimental system.
Summary of the invention
The present invention, for energy consumption in the vacuum pressure measuring technique measuring process that solves existing cold atom experimental system is large and surveying instrument need to take the problem of certain space volume, provides a kind of straightforward procedure and device of measuring cold atom experimental system vacuum pressure.
The present invention adopts following technical scheme to realize: a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure, the method are to adopt following steps to realize:
A. record the loading curve of cold atom experimental system different capture light power under the same background vacuum pressure; According to the loading curve that records, obtain the atom loss factor of cold atom experimental system different capture light power under the same background vacuum pressure
B. to the atom loss factor of cold atom experimental system different capture light power under the same background vacuum pressure
Carry out linear fit; According to the linear fit result, draw the loss factor that cold atom experimental system Atom and background gas collision cause
C. according to cold atom experimental system Atom and background gas, collide the loss factor that causes
, calculate the vacuum pressure of cold atom experimental system
Computing formula is as follows:
In formula:
For proportionality constant, it can calculate acquisition by theory according to the parameter of cold atom experimental system.
The theoretical foundation of a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure of the present invention is as follows:
In present cold atom experimental system, usually by Magneto-Optical Trap, realize capturing with cooling of atom.In the loading process of atom, number of cold atoms can be written as following formula over time:
In formula (1): N is the number of cold atoms in Magneto-Optical Trap, and R is by the charging ratio of laser to atom, and γ is the loss factor that Magneto-Optical Trap Atom and background gas collision cause,
For capturing the average density of atom, β is the loss factor that Magneto-Optical Trap Atom two body inelastic collisions cause.Under isodensity is approximate,
It is a constant.Therefore formula (1) can be separated and is:
In formula (2): loss factor Г can be expressed as:
In the factor that causes the atom loss, atom two body inelastic collision loss factor β mainly change with capturing optical power change; The loss factor γ that atom and background gas collision cause can be expressed as:
In formula (3): i is the kind of background gas, n
iFor background gas density, v
iFor background gas speed, σ
iFor the loss scattering cross-section.The speed of capturing atom is less with respect to the speed of background gas, and angle brackets are for being that of the background gas heat distribution of T is average to temperature;
The loss scattering cross-section is determined by following formula:
In formula (4): θ
LFor the minimum scatter angle of the Magneto-Optical Trap of can escaping,
For the scattering cross-section of differential, C
iFor the Van der Waals coefficient, can calculate by the Slater-Kirkwood equation.D is the well depth of Magneto-Optical Trap, m
0For capturing the quality of atom, E
i=m
iv
i 2/ 2 is the energy of collision setting, background gas density n
iCan also be expressed as n
i=P
i/ k
BT has:
Through type (5) can be found out: the collision of Magneto-Optical Trap Atom and background gas and the proportion of goods damageds γ that causes depends on background gas pressure;
Due to Magneto-Optical Trap Atom and the collision of background gas be mainly with background gas in capture the collision of the similar atom of atom, we can be similar to and think have for certain stable Magneto-Optical Trap:
P=Kγ （6）；
As long as we determine the Magneto-Optical Trap Atom and background gas collides the loss factor γ that causes, we just can obtain the vacuum pressure of Magneto-Optical Trap experimental system.
A kind of device (this device is for realizing a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure of the present invention) of measuring cold atom experimental system vacuum pressure, comprise Magneto-Optical Trap, lens, photodiode detector, controller, the first switch, second switch, data analyzer; Wherein, lens are installed on the idle window of Magneto-Optical Trap; Photodiode detector is installed on the back focus place of lens; The signal input part of the first switch, the signal input part of second switch all are connected with the signal output part of controller; The signal input part of data analyzer is connected with the signal output part of photodiode detector.
During specific works, controller is opened to turn-off to the capture light of Magneto-Optical Trap by the first switch and is controlled, and by second switch, the pump light again of Magneto-Optical Trap is opened to turn-off and control.Atomic fluorescence in Magneto-Optical Trap is to the emission of space all directions, and the atomic fluorescence scioptics that are transmitted into the idle window of Magneto-Optical Trap are assembled collection, then enter photodiode detector.By controller, change the light intensity of capture light, thereby record the loading curve of cold atom experimental system (being Magneto-Optical Trap) different capture light power under the same background vacuum pressure.Data analyzer cut-offs control for the atomic fluorescence to Magneto-Optical Trap, records the atomic fluorescence intensity of Magneto-Optical Trap, and atomic fluorescence intensity is carried out-ln(1-N
t/ N
0) mathematics manipulation, thereby obtain the atom loss factor of cold atom experimental system (being Magneto-Optical Trap) different capture light power under the same background vacuum pressure.By capture light intensity is controlled, obtain the atom loss factor under different capture light intensity, thereby calculate the loss factor that the collision of atom and background gas causes, and then obtain vacuum pressure.
With the vacuum pressure measuring technique of existing cold atom experimental system, compare, a kind of straightforward procedure and device of measuring cold atom experimental system vacuum pressure of the present invention self provided by the cold atom experimental system, and without special vacuum measurement instrument, it has thoroughly avoided the variety of issue that ion gauge, residual gas analyzer, ionic pump exist thus, thereby not only effectively reduce the energy consumption in measuring process, and effectively simplified measuring process.
The present invention efficiently solves the problem that the large and surveying instrument of energy consumption in the vacuum pressure measuring technique measuring process of existing cold atom experimental system need to take the certain space volume, and the vacuum pressure that is applicable to the cold atom experimental system is measured.
The accompanying drawing explanation
Fig. 1 is a kind of structural representation of measuring the device of cold atom experimental system vacuum pressure of the present invention.
Fig. 2 is the loading curve that adopts cold atom experimental system different capture light power under the same background vacuum pressure that a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure of the present invention records.Illustration is to carry out-ln(1-N loading curve data
t/ N
0) the mathematics manipulation result.
Fig. 3 is the atom loss factor that adopts cold atom experimental system different capture light power under the same background vacuum pressure that a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure of the present invention obtains
Schematic diagram.
In figure: 1-Magneto-Optical Trap, 2-lens, 3-photodiode detector, 4-controller, 5-the first switch, 6-second switch, the capture light of 7-Magneto-Optical Trap, the pump light again of 8-Magneto-Optical Trap, 9-data analyzer.
Embodiment
A kind of straightforward procedure of measuring cold atom experimental system vacuum pressure, the method are to adopt following steps to realize:
A. record the loading curve of cold atom experimental system different capture light power under the same background vacuum pressure; According to the loading curve that records, obtain the atom loss factor of cold atom experimental system different capture light power under the same background vacuum pressure
B. to the atom loss factor of cold atom experimental system different capture light power under the same background vacuum pressure
Carry out linear fit; According to the linear fit result, draw the loss factor that cold atom experimental system Atom and background gas collision cause
C. according to cold atom experimental system Atom and background gas, collide the loss factor that causes
, calculate the vacuum pressure of cold atom experimental system
Computing formula is as follows:
In formula:
For proportionality constant, it can calculate acquisition by theory according to the parameter of cold atom experimental system.
A kind of device (this device is for realizing a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure of the present invention) of measuring cold atom experimental system vacuum pressure, comprise Magneto-Optical Trap 1, lens 2, photodiode detector 3, controller 4, the first switch 5, second switch 6, data analyzer 9; Wherein, lens 2 are installed on the idle window of Magneto-Optical Trap 1; Photodiode detector 3 is installed on the back focus place of lens 2; The signal input part of the signal input part of the first switch 5, second switch 6 all is connected with the signal output part of controller 4; The signal input part of data analyzer 9 is connected with the signal output part of photodiode detector 3.
Claims (2)
1. straightforward procedure of measuring cold atom experimental system vacuum pressure is characterized in that: the method is to adopt following steps to realize:
A. record the loading curve of cold atom experimental system different capture light power under the same background vacuum pressure; According to the loading curve that records, obtain the atom loss factor of cold atom experimental system different capture light power under the same background vacuum pressure
B. to the atom loss factor of cold atom experimental system different capture light power under the same background vacuum pressure
Carry out linear fit; According to the linear fit result, draw the loss factor that cold atom experimental system Atom and background gas collision cause
C. according to cold atom experimental system Atom and background gas, collide the loss factor that causes
, calculate the vacuum pressure of cold atom experimental system
Computing formula is as follows:
；
In formula:
For proportionality constant, it can calculate acquisition by theory according to the parameter of cold atom experimental system.
2. device of measuring cold atom experimental system vacuum pressure, this device, for realizing a kind of straightforward procedure of measuring cold atom experimental system vacuum pressure as claimed in claim 1, is characterized in that: comprise Magneto-Optical Trap (1), lens (2), photodiode detector (3), controller (4), the first switch (5), second switch (6), data analyzer (9); Wherein, lens (2) are installed on the idle window of Magneto-Optical Trap (1); Photodiode detector (3) is installed on the back focus place of lens (2); The signal input part of the signal input part of the first switch (5), second switch (6) all is connected with the signal output part of controller (4); The signal input part of data analyzer (9) is connected with the signal output part of photodiode detector (3).
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106546332A (en) * | 2016-11-17 | 2017-03-29 | 山西大学 | Optical frequency measuring system and method based on formation of ultra-cold molecules photoassociation spectrum |
| CN107655622A (en) * | 2017-08-22 | 2018-02-02 | 兰州空间技术物理研究所 | A kind of superelevation based on cold atom/XHV pressure sensor |
| CN112781786A (en) * | 2020-12-14 | 2021-05-11 | 兰州空间技术物理研究所 | Device for measuring ultrahigh or extremely high vacuum by using supercooled atoms and detection method |
| CN114354057A (en) * | 2022-01-05 | 2022-04-15 | 华东师范大学 | Sensing device and method for precisely measuring pressure intensity of cold atom vacuum system |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106546332A (en) * | 2016-11-17 | 2017-03-29 | 山西大学 | Optical frequency measuring system and method based on formation of ultra-cold molecules photoassociation spectrum |
| CN107655622A (en) * | 2017-08-22 | 2018-02-02 | 兰州空间技术物理研究所 | A kind of superelevation based on cold atom/XHV pressure sensor |
| CN112781786A (en) * | 2020-12-14 | 2021-05-11 | 兰州空间技术物理研究所 | Device for measuring ultrahigh or extremely high vacuum by using supercooled atoms and detection method |
| CN114354057A (en) * | 2022-01-05 | 2022-04-15 | 华东师范大学 | Sensing device and method for precisely measuring pressure intensity of cold atom vacuum system |
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Application publication date: 20131120 |