JP2011188352A - Ion-trap type reference frequency generator and method of stabilizing output frequency - Google Patents

Ion-trap type reference frequency generator and method of stabilizing output frequency Download PDF

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JP2011188352A
JP2011188352A JP2010053101A JP2010053101A JP2011188352A JP 2011188352 A JP2011188352 A JP 2011188352A JP 2010053101 A JP2010053101 A JP 2010053101A JP 2010053101 A JP2010053101 A JP 2010053101A JP 2011188352 A JP2011188352 A JP 2011188352A
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Katao Morikawa
容雄 森川
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Anritsu Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion-trap type reference frequency generator that is resistive to pressure of buffer gas, and also to provide a method of stabilizing output frequency. <P>SOLUTION: The ion-trap type reference frequency generator 301 includes an optical pumping device 15 for gathering mercury ion 102 in a vessel 17 to lower level of the basement state with optical pumping, an electromagnetic wave irradiator 13 for transition, to upper level, of the mercury ion 103 gathered to lower level of the basement state with irradiation of the electromagnetic wave, a light receiver 14 for measuring optical strength of fluorescence 23 radiated when the mercury ion 103 enters again the basement state through the excited state by the optical pumping device 15, a controller for adjusting frequency of the electromagnetic wave to obtain maximum optical strength of the fluorescence 23, an output unit for output of frequency of the electromagnetic wave radiated with the electromagnetic wave irradiator 13 as the output frequency, and a gas feeder 25 for supplying, as the buffer gas, a plurality of gases in the mixing ratio to keep constant the output frequency even if pressure changes, to the vessel 17. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、水銀イオンを使用したイオントラップ型周波数標準器及びその出力周波数の安定化方法に関する。   The present invention relates to an ion trap type frequency standard using mercury ions and a method for stabilizing its output frequency.

水銀イオンを使用したイオントラップ型周波数標準器は、水銀イオンを冷却するために容器内にバッファガスが導入されている（例えば、非特許文献１を参照。）。   In an ion trap type frequency standard using mercury ions, a buffer gas is introduced into the container in order to cool the mercury ions (see, for example, Non-Patent Document 1).

Ｓａｎｇ Ｋ． Ｃｈｕｎｇ， Ｊｏｈｎ Ｄ． Ｐｒｅｓｔａｇｅ， Ｒｏｂｅｒｔ Ｌ． Ｔｊｏｅｌｋｅｒ， Ｌｕｔｅ Ｍａｌｅｋｉ，“Ｂｕｆｆｅｒ Ｇａｓ Ｅｘｐｅｒｉｍｅｎｔｓ ｉｎ Ｍｅｒｃｕｒｙ （Ｈｇ＋） Ｉｏｎ Ｃｌｏｃｋ”．Ｐｒｏｃ． Ｏｆ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｆｒｅｑｕｅｎｃｙ Ｃｏｎｔｒｏｌ Ｓｙｍｐｏｓｉｕｍ， ２００４Sang K. Chung, John D. Prestage, Robert L. Tjoelker, Lute Maleki, “Buffer Gas Experiments in Mercury (Hg +) Ion Clock”. Proc. Of International Frequency Control Symposium, 2004

非特許文献１は、バッファガスの導入でイオントラップ型周波数標準器から出力される出力周波数が変動することを報告している。さらに、非特許文献１は、バッファガスの圧力変動に応じて出力周波数も変動することを報告している。これは、イオントラップ型周波数標準器の容器内に導入するバッファガスの圧力の制御精度が、イオントラップ型周波数標準器から出力される出力周波数の精度に影響することを意味する。しかし、求められる出力周波数の精度を得る程度に、バッファガスの圧力を高精度に制御することは困難である。   Non-Patent Document 1 reports that the output frequency output from the ion trap type frequency standard varies with the introduction of the buffer gas. Furthermore, Non-Patent Document 1 reports that the output frequency varies according to the pressure variation of the buffer gas. This means that the control accuracy of the pressure of the buffer gas introduced into the container of the ion trap frequency standard affects the accuracy of the output frequency output from the ion trap frequency standard. However, it is difficult to control the pressure of the buffer gas with high accuracy so as to obtain the required accuracy of the output frequency.

そこで、本発明は、バッファガスの圧力に影響され難いイオントラップ型周波数標準器及び出力周波数安定化方法を提供することを目的とする。   Accordingly, an object of the present invention is to provide an ion trap type frequency standard and an output frequency stabilization method that are hardly affected by the pressure of the buffer gas.

上記目的を達成するために、本発明に係るイオントラップ型周波数標準器及び出力周波数安定化方法は、バッファガスとして複数の希ガスを混合したものを使用することとした。   In order to achieve the above object, the ion trap frequency standard and the output frequency stabilization method according to the present invention use a mixture of a plurality of rare gases as a buffer gas.

具体的には、本発明に係るイオントラップ型周波数標準器は、容器（１７）内の水銀イオンを光ポンピングして前記水銀イオンを基底状態（２Ｓ１／２）の下準位（Ｆ＝０）へ集める光ポンピング手段（１５）と、上準位（Ｆ＝１）と下準位の間のエネルギー差に相当する周波数の電磁波を照射して、前記光ポンピング手段で基底状態の下準位に集まった前記水銀イオンを基底状態の上準位に遷移させる電磁波照射手段（１３）と、前記電磁波照射手段で上準位に遷移した前記水銀イオンが前記光ポンピング手段により再び励起状態を経由して基底状態に戻る際に放射される蛍光の光強度を測定する受光手段（１４）と、前記受光手段で測定した前記蛍光の光強度が最大となるように前記電磁波照射手段が照射する前記電磁波の周波数を調整する制御手段と、前記電磁波照射手段が照射する前記電磁波の周波数を出力周波数として出力する出力手段と、前記水銀イオンを冷却するバッファガスとして、圧力が変動しても前記出力手段が出力する出力周波数を一定に保つ混合比の複数のガスを前記容器に供給するガス供給手段（２５）と、を備える。 Specifically, an ion trap frequency standard according to the present invention, the lower level of containers mercury ions by optical pumping the mercury ions to the ground state in the (17) (2 S 1/2) (F = And an optical pumping means (15) that collects to 0) and an electromagnetic wave having a frequency corresponding to the energy difference between the upper level (F = 1) and the lower level, and the lower level of the ground state is irradiated by the optical pumping means. Electromagnetic wave irradiating means (13) for transitioning the mercury ions gathered at the upper level to the upper level of the ground state, and the mercury ions having shifted to the upper level by the electromagnetic wave irradiating means again pass through the excited state by the optical pumping means. The light receiving means (14) for measuring the light intensity of the fluorescence emitted when returning to the ground state, and the electromagnetic wave irradiation means for irradiating the light intensity of the fluorescence measured by the light receiving means so as to maximize the light intensity. Adjust the frequency of electromagnetic waves Control means for adjusting, output means for outputting the frequency of the electromagnetic wave irradiated by the electromagnetic wave irradiation means as an output frequency, and output as output from the output means even when pressure fluctuates as a buffer gas for cooling the mercury ions Gas supply means (25) for supplying a plurality of gases having a mixing ratio to keep the frequency constant to the container.

本発明に係るイオントラップ型周波数標準器の前記ガス供給手段は、圧力上昇で前記出力手段が出力する出力周波数が上昇する正の周波数シフト率をもつガスと圧力上昇で前記出力手段が出力する出力周波数が下降する負の周波数シフト率をもつガスとを混合することを特徴とする。   The gas supply means of the ion trap type frequency standard according to the present invention includes a gas having a positive frequency shift rate at which the output frequency output by the output means increases with an increase in pressure and an output output by the output means with an increase in pressure. It is characterized by mixing with a gas having a negative frequency shift rate at which the frequency decreases.

本発明に係る出力周波数安定化方法は、容器内の水銀イオンを光ポンピングして前記水銀イオンを基底状態の下準位へ集め、上準位と下準位の間のエネルギー差に相当する周波数の電磁波を照射して前記水銀イオンを基底状態の上準位に遷移させ、前記水銀イオンが上準位から前記光ポンピング手段により再び励起状態を経由して基底状態に戻る際に放射される蛍光の強度を測定し、前記蛍光の光強度が最大となるように前記電磁波の周波数を調整し、前記電磁波の周波数を出力周波数として出力する際に、前記水銀イオンを冷却するバッファガスとして、圧力が変動しても前記出力手段が出力する出力周波数を一定に保つ混合比の複数のガスを前記容器に供給する。   The output frequency stabilization method according to the present invention optically pumps mercury ions in a container, collects the mercury ions to the lower level of the ground state, and a frequency corresponding to an energy difference between the upper level and the lower level. Fluorescence emitted when the mercury ion returns from the upper level to the ground state again via the excited state by the optical pumping means. When the frequency of the electromagnetic wave is adjusted so that the light intensity of the fluorescence is maximized, and the frequency of the electromagnetic wave is output as an output frequency, the buffer gas that cools the mercury ions has a pressure as a buffer gas. Even if it fluctuates, a plurality of gases having a mixture ratio that keeps the output frequency output by the output means constant is supplied to the container.

本発明に係る出力周波数安定化方法は、前記バッファガスとして、圧力上昇で前記出力手段が出力する出力周波数が上昇する正の周波数シフト率をもつガスと圧力上昇で前記出力手段が出力する出力周波数が下降する負の周波数シフト率をもつガスとを混合することを特徴とする。   In the output frequency stabilization method according to the present invention, as the buffer gas, a gas having a positive frequency shift rate at which the output frequency output by the output means increases with an increase in pressure, and an output frequency output by the output means with an increase in pressure. It is characterized by mixing with a gas having a negative frequency shift rate at which descents.

本発明は、正の周波数シフト率をもつガスと負の周波数シフト率をもつガスとを所定の混合比で混合したものをバッファガスとしている。このバッファガスを容器内に導入することで容器内の圧力が変動しても出力周波数を一定に保つことができる。従って、本発明は、バッファガスの圧力に影響され難いイオントラップ型周波数標準器及び出力周波数安定化方法を提供することができる。すなわち、バッファガスの圧力を高精度に制御することが不要になる。   In the present invention, a buffer gas is obtained by mixing a gas having a positive frequency shift rate and a gas having a negative frequency shift rate at a predetermined mixing ratio. By introducing this buffer gas into the container, the output frequency can be kept constant even if the pressure in the container fluctuates. Therefore, the present invention can provide an ion trap type frequency standard and an output frequency stabilization method that are hardly influenced by the pressure of the buffer gas. That is, it becomes unnecessary to control the pressure of the buffer gas with high accuracy.

本発明は、バッファガスの圧力に影響され難いイオントラップ型周波数標準器及び出力周波数安定化方法を提供することができる。   INDUSTRIAL APPLICABILITY The present invention can provide an ion trap type frequency standard and an output frequency stabilization method that are hardly affected by the pressure of the buffer gas.

本発明に係るイオントラップ型周波数標準器を説明する図である。It is a figure explaining the ion trap type | mold frequency standard device which concerns on this invention. 本発明に係るイオントラップ型周波数標準器とバッファガス供給手段を説明する図である。It is a figure explaining the ion trap type | mold frequency standard device and buffer gas supply means which concern on this invention. 水銀イオンエネルギー準位を説明する図である。It is a figure explaining a mercury ion energy level. バッファガスの圧力に対する出力周波数の周波数シフトを説明する図である。It is a figure explaining the frequency shift of the output frequency with respect to the pressure of buffer gas.

以下、具体的に実施形態を示して本発明を詳細に説明するが、本願の発明は以下の記載に限定して解釈されない。なお、本明細書及び図面において符号が同じ構成要素は、相互に同一のものを示すものとする。   Hereinafter, the present invention will be described in detail with specific embodiments, but the present invention is not construed as being limited to the following description. In the present specification and drawings, the same reference numerals denote the same components.

図１は、本実施形態のイオントラップ型周波数標準器３０１を説明する図である。イオントラップ型周波数標準器３０１は、容器１７内の水銀イオン１０２を光ポンピングして水銀イオン１０２を基底状態の下準位へ集める光ポンピング手段１５と、上準位と下準位の間のエネルギー差に相当する周波数の電磁波を照射して、光ポンピング手段１５で基底状態の下準位に集まった水銀イオン１０３を上準位へ遷移させる電磁波照射手段１３と、電磁波照射手段１３で上準位へ遷移した水銀イオン１０３が光ポンピング手段１５により再び基底状態へ戻る際に放射される蛍光２３の光強度を測定する受光手段１４と、受光手段１４で測定した蛍光２３の光強度が最大となるように電磁波照射手段１３が照射する電磁波の周波数を調整する制御手段（不図示）と、電磁波照射手段１３が照射する電磁波の周波数を出力周波数として出力する出力手段（不図示）と、水銀イオン（１０２、１０３）を冷却するバッファガスとして、圧力が変動しても出力手段が出力する出力周波数を一定に保つ混合比の複数のガスを容器１７に供給するガス供給手段２５と、を備える。   FIG. 1 is a diagram for explaining an ion trap type frequency standard 301 according to this embodiment. The ion trap type frequency standard 301 is an optical pumping means 15 for optically pumping the mercury ions 102 in the container 17 and collecting the mercury ions 102 to the lower level of the ground state, and the energy between the upper level and the lower level. An electromagnetic wave irradiation means 13 for irradiating an electromagnetic wave having a frequency corresponding to the difference and causing the optical pumping means 15 to transition the mercury ions 103 collected at the lower level of the ground state to the upper level, and the electromagnetic wave irradiation means 13 for the upper level. The light-receiving means 14 for measuring the light intensity of the fluorescence 23 emitted when the mercury ion 103 that has transitioned to the ground state again returns to the ground state by the optical pumping means 15, and the light intensity of the fluorescence 23 measured by the light-receiving means 14 is maximized. The control means (not shown) for adjusting the frequency of the electromagnetic wave irradiated by the electromagnetic wave irradiation means 13 and the frequency of the electromagnetic wave irradiated by the electromagnetic wave irradiation means 13 as the output frequency As a buffer gas for cooling the output means (not shown) for outputting and the mercury ions (102, 103), a plurality of gases having a mixing ratio that keeps the output frequency output by the output means constant even when the pressure fluctuates is stored in the container 17. Gas supply means 25 for supplying to

水銀源１０１は、容器１７内に水銀蒸気を供給する。電子銃１６は電子線２２で水銀蒸気を水銀イオンにイオン化する。四重極トラップ１８は、１〜２ＭＨｚのＲＦ電圧が印加されており、水銀イオンを中心部に閉じ込める。図１では、この様子を水銀イオン１０２として示している。光ポンピング手段１５は、波長１９４．２ｎｍの励起光２１を出力する水銀ランプである。   The mercury source 101 supplies mercury vapor into the container 17. The electron gun 16 ionizes mercury vapor into mercury ions with an electron beam 22. The quadrupole trap 18 is applied with an RF voltage of 1 to 2 MHz and traps mercury ions in the center. In FIG. 1, this state is shown as mercury ions 102. The optical pumping means 15 is a mercury lamp that outputs excitation light 21 having a wavelength of 194.2 nm.

光ポンピングについて、図３の水銀イオンのエネルギー準位の図で説明する。水銀イオンは２つのエネルギー状態、つまり基底状態２Ｓ１／２と励起状態２Ｐ１／２を持ち、基底状態は二つのエネルギー準位（Ｆ＝０、１）から構成される。ここで、光ポンピング手段１５から励起光２１を照射すると、基底状態の準位Ｆ＝１にあるイオンのみが励起状態へ遷移する。しかし、励起状態に遷移したイオンは、すぐに基底状態へ戻る。このとき、イオンはそれぞれの準位（Ｆ＝０、１）に均等に遷移する。そして、基底状態の準位Ｆ＝１に戻ったイオンは、励起光２１を吸収して再び励起状態へ上がる。一方、基底状態の準位Ｆ＝０にあるイオンは、そのまま残る。これを繰り返すことで、全てのイオンは基底状態の準位Ｆ＝０に集まる。 The optical pumping will be described with reference to the energy level diagram of mercury ion in FIG. Mercury ions have two energy states, namely a ground state 2 S 1/2 and an excited state 2 P 1/2 , and the ground state is composed of two energy levels (F = 0, 1). Here, when the excitation light 21 is irradiated from the optical pumping means 15, only the ions in the ground state level F = 1 transition to the excitation state. However, the ions that have transitioned to the excited state immediately return to the ground state. At this time, the ions uniformly transition to the respective levels (F = 0, 1). Then, the ions that have returned to the ground state level F = 1 absorb the excitation light 21 and rise to the excited state again. On the other hand, ions in the ground state level F = 0 remain as they are. By repeating this, all ions gather at the ground state level F = 0.

十二重極トラップ１９も、１〜２ＭＨｚのＲＦ電圧が印加されており、水銀イオンを中心部に閉じ込めることができる。十二重極トラップ１９は、光ポンピングされた水銀イオン１０２を四重極トラップ１８から取り出し、中心部に閉じ込める。図１では、この様子を水銀イオン１０３として示している。   The doubly-polar trap 19 is also applied with an RF voltage of 1 to 2 MHz and can confine mercury ions in the center. The ten-pole trap 19 takes out the optically pumped mercury ions 102 from the quadrupole trap 18 and confines them in the center. In FIG. 1, this state is shown as mercury ions 103.

電磁波照射手段１３は、例えば、４０ＧＨｚ導波管である。電磁波照射手段１３は、制御手段で周波数が設定された電磁波を水銀イオン１０３に照射する。このときの水銀イオン１０３の様子を図３の水銀イオンのエネルギー準位の図で説明する。光ポンピング直後の水銀イオン１０３は基底状態の準位Ｆ＝０にある。周波数４０．５ＧＨｚの電磁波が照射されると、基底状態の準位Ｆ＝０にあるイオンは同じ基底状態の準位Ｆ＝１に遷移する。このとき、電磁波の周波数が４０．５ＧＨｚからずれると基底状態の準位Ｆ＝０から準位Ｆ＝１へ遷移するイオンの量が少なくなる。   The electromagnetic wave irradiation means 13 is, for example, a 40 GHz waveguide. The electromagnetic wave irradiation means 13 irradiates the mercury ions 103 with an electromagnetic wave whose frequency is set by the control means. The state of the mercury ion 103 at this time will be described with reference to the energy level diagram of the mercury ion in FIG. The mercury ion 103 immediately after the optical pumping is at the ground state level F = 0. When an electromagnetic wave with a frequency of 40.5 GHz is irradiated, ions in the ground state level F = 0 transition to the same ground state level F = 1. At this time, when the frequency of the electromagnetic wave deviates from 40.5 GHz, the amount of ions that transition from the ground state level F = 0 to the level F = 1 decreases.

続いて、四重極トラップ１８は電磁波が照射された水銀イオン１０３を十二重極トラップ１９から取り出し、再び中心部に閉じ込める。図１では、この様子を水銀イオン１０２として示している。四重極トラップ１８では光ポンピング手段１５から励起光２１が照射されているので、水銀イオン１０２の基底状態の準位Ｆ＝１にあるイオンは励起状態へ遷移することになる。そして、励起状態へ遷移したイオンは、すぐに蛍光２３を出して基底状態へ戻る。   Subsequently, the quadrupole trap 18 takes out the mercury ions 103 irradiated with the electromagnetic wave from the dodecapole trap 19 and confines them again in the center. In FIG. 1, this state is shown as mercury ions 102. Since the excitation light 21 is irradiated from the optical pumping means 15 in the quadrupole trap 18, ions in the ground state level F = 1 of the mercury ion 102 transition to the excitation state. The ions that have transitioned to the excited state immediately emit fluorescence 23 and return to the ground state.

受光手段１４は、蛍光２３の光強度を測定する。ここで、前述のように電磁波照射手段１３が照射した電磁波の周波数が４０．５ＧＨｚからずれていると基底状態の準位Ｆ＝１にあるイオンが少ないので、蛍光２３の光強度が弱くなる。そこで、制御手段は、蛍光２３の光強度が最大となるように電磁波の周波数を調整する。出力手段は、制御手段が調整した電磁波の周波数を出力周波数として出力する。イオントラップ型周波数標準器３０１は、このようにして、正確な４０．５ＧＨｚの周波数を出力することができる。なお、イオントラップ型周波数標準器３０１は、磁場の影響を低減するための磁場シールド１１及びエネルギー状態の縮退を解くＣコイル１２も備えている。   The light receiving means 14 measures the light intensity of the fluorescence 23. Here, when the frequency of the electromagnetic wave irradiated by the electromagnetic wave irradiation means 13 deviates from 40.5 GHz as described above, the number of ions in the ground state level F = 1 is small, and thus the light intensity of the fluorescence 23 is weakened. Therefore, the control means adjusts the frequency of the electromagnetic wave so that the light intensity of the fluorescence 23 is maximized. The output means outputs the frequency of the electromagnetic wave adjusted by the control means as an output frequency. In this way, the ion trap type frequency standard 301 can output an accurate frequency of 40.5 GHz. The ion trap type frequency standard 301 includes a magnetic field shield 11 for reducing the influence of the magnetic field and a C coil 12 for solving the degeneracy of the energy state.

さらに、ガス供給手段２５は、容器１７内にバッファガスを供給する。水銀イオン（１０２、１０３）は高温になると、四重極トラップ１８内や十二重極トラップ１９内に閉じ込めることが難しくなる。このため、水銀イオンをバッファガスに衝突させて水銀イオンの温度を下げる必要がある。ところが、非特許文献１で説明されるようにバッファガスの圧力変動は出力周波数の変動をひきおこす。図４は、バッファガスとしてＡｒ、Ｎｅ、Ｈｅを使った場合のガス圧力Ｐ（Ｔｏｒｒ）に対する出力周波数ｆ（Ｈｚ）の周波数シフトを説明する図である。ここで、
（ｄｆ／ｄＰ）・（１／ｆ）
を周波数シフト率と定義する。図４より、
Ａｒの周波数シフト率＝−４．１×１０−７（／Ｔｏｒｒ）
Ｎｅの周波数シフト率＝８．５×１０−９（／Ｔｏｒｒ）
Ｈｅの周波数シフト率＝２．１×１０−８（／Ｔｏｒｒ）
である。 Further, the gas supply means 25 supplies buffer gas into the container 17. Mercury ions (102, 103) are difficult to confine in the quadrupole trap 18 or the dodecapole trap 19 at a high temperature. For this reason, it is necessary to make mercury ion collide with buffer gas and to reduce the temperature of mercury ion. However, as explained in Non-Patent Document 1, fluctuations in the pressure of the buffer gas cause fluctuations in the output frequency. FIG. 4 is a diagram for explaining the frequency shift of the output frequency f (Hz) with respect to the gas pressure P (Torr) when Ar, Ne, and He are used as the buffer gas. here,
(Df / dP) · (1 / f)
Is defined as a frequency shift rate. From FIG.
Ar frequency shift rate = −4.1 × 10 −7 (/ Torr)
Ne frequency shift rate = 8.5 × 10 −9 (/ Torr)
He frequency shift rate = 2.1 × 10 −8 (/ Torr)
It is.

図２は、イオントラップ型周波数標準器３０１のガス供給手段２５を説明する図である。ガス供給手段２５は、２つのガスボンベ（３１Ａ、３１Ｂ）、２つのリークバルブ（３２Ａ、３２Ｂ）及び２つのガスを混合する混合部３３を有する。ガス供給手段２５は、正の周波数シフト率をもつガスと負の周波数シフト率をもつガスとを混合する。例えば、ガスボンベ３１ＡにＡｒを入れ、ガスボンベ３１ＢにＨｅを入れる。混合部３３は、ＡｒとＨｅを混合し、バッファガスとして容器１７に導入する。このとき、リークバルブ（３２Ａ、３２Ｂ）を調整し、容器１７内のバッファガスの圧力で出力周波数が変動しないようにＡｒとＨｅを混合する。   FIG. 2 is a diagram for explaining the gas supply means 25 of the ion trap type frequency standard 301. The gas supply means 25 includes two gas cylinders (31A, 31B), two leak valves (32A, 32B), and a mixing unit 33 that mixes two gases. The gas supply means 25 mixes a gas having a positive frequency shift rate and a gas having a negative frequency shift rate. For example, Ar is put into the gas cylinder 31A, and He is put into the gas cylinder 31B. The mixing unit 33 mixes Ar and He and introduces them into the container 17 as a buffer gas. At this time, the leak valve (32A, 32B) is adjusted, and Ar and He are mixed so that the output frequency does not fluctuate due to the pressure of the buffer gas in the container 17.

イオントラップ型周波数標準器３０１は、ＡｒとＨｅを混合したものをバッファガスとして使用することで、水銀イオンとバッファガスとの衝突による周波数シフトを打ち消し、バッファガスの圧力が変化しても出力周波数を一定に保つことができる。このため、イオントラップ型周波数標準器３０１は、バッファガスの圧力を高精度に制御する必要がない。   The ion trap type frequency standard 301 uses a mixture of Ar and He as a buffer gas, thereby canceling the frequency shift caused by the collision between mercury ions and the buffer gas, and the output frequency even if the pressure of the buffer gas changes. Can be kept constant. For this reason, the ion trap type frequency standard 301 does not need to control the pressure of the buffer gas with high accuracy.

１１：磁場シールド
１２：Ｃコイル
１３：電磁波照射手段
１４：受光手段
１５：光ポンピング手段
１６：電子銃
１７：容器
１８：四重極トラップ
１９：十二重極トラップ
２１：励起光
２２：電子線
２３：蛍光
２５：ガス供給手段
１０１：水銀源
１０２、１０３：水銀イオン
３０１：イオントラップ型周波数標準器 11: Magnetic field shield 12: C coil 13: Electromagnetic wave irradiation means 14: Light receiving means 15: Optical pumping means 16: Electron gun 17: Container 18: Quadrupole trap 19: Doubly pole trap 21: Excitation light 22: Electron beam 23: Fluorescence 25: Gas supply means 101: Mercury source 102, 103: Mercury ion 301: Ion trap type frequency standard

Claims (4)

容器（１７）内の水銀イオンを光ポンピングして前記水銀イオンを基底状態の下準位へ集める光ポンピング手段（１５）と、
上準位と下準位の間のエネルギー差に相当する周波数の電磁波を照射して、前記光ポンピング手段で基底状態の下準位に集まった前記水銀イオンを基底状態の上準位へ遷移させる電磁波照射手段（１３）と、
前記電磁波照射手段で上準位へ遷移した前記水銀イオンが前記光ポンピング手段により再び励起状態を経由して基底状態に戻る際に放射される蛍光の光強度を測定する受光手段（１４）と、
前記受光手段で測定した前記蛍光の光強度が最大となるように前記電磁波照射手段が照射する前記電磁波の周波数を調整する制御手段と、
前記電磁波照射手段が照射する前記電磁波の周波数を出力周波数として出力する出力手段と、
前記水銀イオンを冷却するバッファガスとして、圧力が変動しても前記出力手段が出力する出力周波数を一定に保つ混合比の複数のガスを前記容器に供給するガス供給手段（２５）と、
を備えるイオントラップ型周波数標準器。 Optical pumping means (15) for optically pumping mercury ions in the container (17) and collecting the mercury ions to a lower level of a ground state;
Irradiate an electromagnetic wave having a frequency corresponding to the energy difference between the upper level and the lower level, and the optical pumping means causes the mercury ions collected at the lower level of the ground state to transition to the upper level of the ground state. Electromagnetic wave irradiation means (13);
A light receiving means (14) for measuring the light intensity of the fluorescence emitted when the mercury ion that has transitioned to the upper level by the electromagnetic wave irradiation means returns to the ground state via the excited state again by the optical pumping means;
Control means for adjusting the frequency of the electromagnetic wave emitted by the electromagnetic wave irradiation means so that the light intensity of the fluorescence measured by the light receiving means is maximized;
An output means for outputting the frequency of the electromagnetic wave emitted by the electromagnetic wave irradiation means as an output frequency;
Gas supply means (25) for supplying a plurality of gases having a mixture ratio that keeps the output frequency output by the output means constant even when the pressure fluctuates, as a buffer gas for cooling the mercury ions,
Ion trap type frequency standard equipped with. 前記ガス供給手段は、
圧力上昇で前記出力手段が出力する出力周波数が上昇する正の周波数シフト率をもつガスと圧力上昇で前記出力手段が出力する出力周波数が下降する負の周波数シフト率をもつガスとを混合することを特徴とする請求項１に記載のイオントラップ型周波数標準器。 The gas supply means includes
Mixing a gas having a positive frequency shift rate at which the output frequency output from the output means increases with an increase in pressure and a gas having a negative frequency shift rate at which the output frequency output from the output means decreases due to a pressure increase. The ion trap type frequency standard according to claim 1. 容器内の水銀イオンを光ポンピングして前記水銀イオンを基底状態の下準位へ集め、上準位と下準位の間のエネルギー差に相当する周波数の電磁波を照射して前記水銀イオンを基底状態の上準位へ遷移させ、前記水銀イオンが上準位から前記光ポンピング手段により再び励起状態を経由して基底状態に戻る際に放射される蛍光の強度を測定し、前記蛍光の光強度が最大となるように前記電磁波の周波数を調整し、前記電磁波の周波数を出力周波数として出力する際に、
前記水銀イオンを冷却するバッファガスとして、圧力が変動しても前記出力手段が出力する出力周波数を一定に保つ混合比の複数のガスを前記容器に供給する出力周波数安定化方法。 The mercury ions in the container are optically pumped to collect the mercury ions to the lower level of the ground state, and then irradiated with electromagnetic waves having a frequency corresponding to the energy difference between the upper level and the lower level, Transition to the upper level of the state, measure the intensity of the fluorescence emitted when the mercury ions return from the upper level to the ground state again through the excited state by the optical pumping means, the light intensity of the fluorescence When the frequency of the electromagnetic wave is adjusted so as to be maximum and the frequency of the electromagnetic wave is output as an output frequency,
An output frequency stabilization method for supplying, to the container, a plurality of gases having a mixture ratio that keeps the output frequency output by the output means constant even when the pressure fluctuates as a buffer gas for cooling the mercury ions. 前記バッファガスとして、
圧力上昇で前記出力手段が出力する出力周波数が上昇する正の周波数シフト率をもつガスと圧力上昇で前記出力手段が出力する出力周波数が下降する負の周波数シフト率をもつガスとを混合することを特徴とする請求項３に記載の出力周波数安定化方法。 As the buffer gas,
Mixing a gas having a positive frequency shift rate at which the output frequency output from the output means increases with an increase in pressure and a gas having a negative frequency shift rate at which the output frequency output from the output means decreases due to a pressure increase. The output frequency stabilization method according to claim 3.
JP2010053101A 2010-03-10 2010-03-10 Ion-trap type reference frequency generator and method of stabilizing output frequency Pending JP2011188352A (en)

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