SU811186A1 - Quntum magnetometer - Google Patents

Description

one

The invention relates to the field of instrumentation and can be used to build quantum magnetometers that measure weak magnetic fields on Earth and in space.

A quantum frequency standard is known in which an absorption cell filled with an atomic gas and a spectral lamp, in which the discharge is carried out by a strong high-frequency field, is housed in a single non-magnetic package. The heat of the surface of a balloon of a spectral lamp, heated by luminescence to a temperature of 110 ° C, heats the absorption cell by convective means and maintains its operating temperature of 70 ° C if the external temperature is positive (about) and varies in a small range 1.

A quantum magnetometer is also known, in which only the absorption cell is heated by a carbon cloth or bifillary winding located directly on the cell surface. These elements of the preheating absorption cell are connected to a high frequency generator or a DC source 2J.

With highly accurate magnetic field measurements, the listed cell heating methods introduce large errors. In addition, the dyon cells, through which the pumping light passes, have a lower temperature than the rest of the cell surface, since there is no heating element on them. This impairs the quality of the cell over time and reduces the accuracy of measurements.

The closest technical solution to the invention is a device comprising an optically pumped sensor with a spectral lamp, a control and working photodiodes, an absorption cell, a radio frequency coil, surrounding: the absorbing cell, focusing lenses, a circular polarizer and a thermal sensor, mounted on the surface of the absorption cell, as well as a high frequency generator and a precession signal amplifier 3.

Its disadvantages are the errors in measuring the magnetic field as a result of the action of a powerful high-frequency field (MHz), which excites the discharge in a spectral lamp located in one housing near the absorption cell; the effect of the magnetic field of the heater itself on the working atomic gas in this cell. In the region of low temperatures -30-40 ° С, when

a large heat transfer from the spectral lamp is required (for convective heating of the cell), its surface darkens rapidly. Lamp life is reduced. If the absorption cell has an operating temperature (for example, a cesium cell), then placing it in one common housing with a spectral lamp may cause the cell to overheat. This leads to a decrease in the signal-to-noise ratio and, consequently, to an increase in errors in the measurement of the magnetic field. The aim of the invention is to improve the measurement accuracy over a wide range of changes in ambient temperature. The goal is achieved by the fact that in a quantum magnetometer, there is an optical pumped laser with a spectral lamp, a control and working photodiodes, an absorption cell, a radio frequency coil, an ambient absorption cell, focusing lenses, a circular polarizer and a thermal sensor, a disposable lens inside. on the surface of the absorption cell, as well as a high-frequency generator and a precession signal amplifier, the sensor body is made in the form of two thermally stabilized tanks separated by thermal insulation translational partition with an opening into which one of the lenses and circulating molecular polarizer has, in one of the tanks has spectral lamp and photodiode control. In addition, the thermally stabilized reservoir enclosing the absorption cell is made in the form of a thermal conductor built on the principle of a closed evaporation-condensation system with a heater at one of its ends. The drawing shows a functional diagram of a quantum magnetometer. The quantum magnetometer is equipped with a high-frequency generator 1, a capacitor with plates 2, a spectral lens 3, a control photodiode 4, a nonmagnetic metal body 5 with a hole 6 in it and in a heat insulating partition 7, fixing lenses 8, a circular iolizer 9, body 10, permanently in the form of a thermal conductor enclosing an AND cell, an RF coil 12, a precession amplifier 13, a working photodiode 14, a thermal sensor 15, and a heater 16. The quantum magnetometer works as follows. The high-frequency generator 1, the output power of which is supplied to the plates 2 of the capacitor, excites an electrical component E with a high-frequency, elec- trodeless discharge in the spectral lamp 3. Its intensity is recorded by the control photodiode 4 connected to the generator 1 and stabilized by adjusting the power of this generator. To eliminate the effect of high-frequency bioni of generator 1 (in practice, the power acting on capacitor plates 2 is 1 –3 W) on the precession frequency of atoms in the cell, case 5 is made of metal and non-magnetic and has the character of a closed volume with a small (6n-8 mm) hole. 6 in it and in the heat insulating partition 7. The housing 5, together with the heat insulation partition 7, represents one of the thermally stabilized reservoirs for the spectral lamp 3, inside which the operating temperature (110 ° C) is determined, which is determined by the heat transfer from the balloon of the spectral lamp. Hole 6 in the heat insulating partition 7 serves to transmit light to the pump. In housing 5, it is small and does not transmit the high-frequency exciting field from the spectral lamp 3. In the region of the heat insulating partition, the aperture 6 expands. It contains a lens 8 and a circular polarizer 9. They prevent the penetration of heat to the cell from the spectral lamp by convection of heated air and thermal contact with another part of the housing 10, which is the second thermally stabilized reservoir required for the cell. absorption 11. The absorption cell filled with atoms of the working gas (cesium, rubidium, potassium) and the amotane radio frequency coil 12. It excites the coherent precession of atoms in the cell and is connected to the output of the amplifier 13. The input of the amplifier 1 3 is connected to a working photodiode 14, which registers a precession signal and closes the feedback circuit of the sensor of a quantum magnetometer, which generates at frequency u. (here, the gyromagnetization of atoms, HQ is the modulus of the magnetic field in the region of the absorption cell 11). The working photodiode 14 placed in the housing 10 is also stabilized by temperature. The housing 10 is made in the form of a nonmagnetic thermal conductor with a cavity at one end. In this cavity, the working temperature set by the thermal sensor 15 is determined by the absorption cell (for cesium cells: 25-f-40 ° C; for rubidium 35-50 ° C). The heat conductor operating on the principle of a closed evaporative-condensation system is made in the form of a double-wall flexible heat pipe, between which the wicks and the working fluid are located. The heat conductor thus constructed has heat transfer from the heated end, which is rigidly connected to the heater 16, to the cavity in which the absorption cell I is located. The connection of the thermal sensor 15 to the heater 16 closes the thermal control circuit and stabilizes

Claims (2)

The claims of the invention whereby a spectral lamp, a control and working photodiodes, an absorption cell, a radio frequency coil surrounding the absorption cell, focusing lenses, a circular polarizer and a temperature sensor mounted on the surface of the absorption cell, as well as a high-frequency generator and precession signal amplifier, characterized in that, with 0 aim to improve the measurement accuracy in a wide range of changes in external temperature, the sensor housing is made in the form of two thermostabilized tanks, divided A heat-insulating partition with an opening in which one of the lenses and a circular polarizer are placed, moreover, in one of the tanks there is a spectral lamp and a control photodiode. 0 2. Quantum magnetometer, by π. 1, characterized in that the thermostabilized reservoir enclosing the absorption cell is made in the form of a thermal conductor, constructed according to principle 5 of a closed evaporation-condensation system with a heater at one of its ends.