Spin-coupling nuclear magnetic resonance magnetometer utilizing the same coil for excitation and signal pick-up and using toroidal samples

Claim 2

A nuclear magnetic resonance magnetometer of the spincoupling type comprising: two samples located close to each other in the magnetic field to be measured and containing the same atomic nuclei having nonzero magnetic moment and kinetic moment and a paramagnetic substance having at least an electronic resonance line saturable by an electromagnetic field; two axially aligned identical excitation and pick-up coils each associated with a respective one of said samples, each of said samples comprising a hollow toroid with each coil located within the hollow portion of the toroid; means for producing an electromagnetic field coupled with said samples to saturate an electron resonance line of one of the samples to produce an increase in energy absorption at the resonant frequency of the atomic nuclei and an electron resonance line of the other sample to produce an energy emission at said resonant frequency of the atomic nuclei; a differential amplifier associated with said two coils, one terminal of each coil being connected to a fixed reference voltage and the other terminal of each coil being connected to a respective input of the amplifier whereby the parasitic voltages which are induced in the coils appear in common mode and the output of the amplifier being connected to the inputs thereof through respective impedances having a same value which is large with respect to the impedance of the coils; and means for measuring the frequency at the output of said amplifier.

Claim 3

A magnetometer according to claim 1, wherein the amplifier provides a phase shift of pi /2 and a resonance tuning capacitor is connected between the inputs of the amplifier.

Claim 4

A nuclear magnetic resonance magnetometer of the spin-coupling type comprising: two samples located close to each other in the field to be measured and containing the same atomic nuclei having non-zero magnetic moment and kinetic moment and a paramagnetic substance having at least an electronic resonance line saturable by a VHF electromagnetic field; means for saturating one line of one of the samples so selected as to increase the energy absorption at the resonant frequency of the atomic nuclei and for saturating one line of the other sample so selected as to increase the energy emission at said resonant frequency of the atomic nuclei; a resonant circuit comprising a low-frequency amplifier and at least two identical coils each electromagnetically coupled with one of said samples and connected to the amplifier, each of the samples comprising a hollow toroid with each coil located within the hollow portion of the toroid; and means for measuring the resonant frequency in said resonant circuit.

Claim 5

A nuclear magnetic resonance magnetometer of the spin-coupling type comprising: two samples located close to each other in the field to be measured and containing the same atomic nuclei having non-zero magnetic moment and kinetic moment and a paramagnetic substance having at least an electronic resonance line saturable by a VHF electromagnetic field; means for saturating one line of one of the samples so selected as to increase the energy absorption at the resonant frequency of the atomic nuclei and for saturating one line of the other sample so selected as to increase the energy emission at said resonant frequency of the atomic nuclei; a resonant circuit comprising a low-frequency amplifier and at least two identical coils each electromagnetically coupled with one of said samples and connected to the amplifier, each of the samples comprising a hollow toroid with each coil located within the hollow portion of the toroid; and means for measuring the resonant frequency in said resonant circuit.

Claim 6

A magnetometer according to claim 3, wherein the cross-section taken axially through the toroid of each sample is rectangular or square.

Claim 7

A magnetometer according to claim 4, wherein each toroidal sample consists of two annular flasks limiting a closed annular space for the corresponding coil.

Claim 8

A magnetometer according to claim 4, wherein each coil has a substantially square axial cross-section.

Claim 9

A magnetometer according to claim 1, wherein the means for saturating the electron resonance lines comprises: a VHF resonant cavity consisting of a central conductor located along the axis of the coils and of a shielding which encloses the samples and the coils, said shielding being formed by thin metal strips of high electrical conductivity; and a very-high-frequency generator connected to said cavity by a coaxial cable having a central line connected to the central conductor of the cavity and a shielding which is connected to said conductive strips.

Claim 10

A magnetometer according to claim 7, having a cavity-tuning capacitor consisting of a flat quartz disc which is applied against one of the samples and has the same diameter as said sample, said disc having coatings of conductive metal on the opposite faces thereof, the deposits formed on one of the faces being connected to the central conductor of the cavity and the deposits formed on the other face being connected to the conductive strips.

Claim 11

A magnetometer according to claim 1, wherein one of the samples is constituted by TANO in a 10 3 M solution in pure DME and wherein the other sample is constituted by TANO in a 10 3 M solution in pure methanol and said means comprise a single VHF generator.

Claim 12

A proton magnetometer according to claim 9, wherein the TANO is deuterated.

Claim 13

A nuclear magnetic resonance magnetometer of the spin-coupling type comprising: two samples located close to each other in the magnetic field to be measured and containing the same atomic nuclei having non-zero magnetic moment and kinetic moment and a paramagnetic substance having at least an electron resonance line saturable by a VHF electromagnetic field; two axially aligned identical coils each associated with a respective one of said samples; means for producing an electromagnetic field coupled with said samples to saturate an electron resonance line of one of the samples so as to produce an increase in energy absorption at the resonant frequency of the atomic nuclei and an electron resonance line of the other sample so as to produce an energy emission at said resonant frequency of the atomic nuclei; a resonant circuit for sustaining the nuclear magnetic resonance of said nuclei, comprising a low frequency amplifier and at least said two coils each electromagnetically coupled with one of said samples and connected to said amplifier; and means for measuring the resonance frequency in said loop; wherein the means for producing an electromagnetic field at the electron resonance frequency comprise a single VHF oscillator, a resonant cavity, and a coaxial cable, said cavity having a central conductor disposed along the common axis of the coils and a shielding which encloses the samples and the coils and is formed by longitudinal strips of highly electrically conductive metal and said coaxial cable having an inner conductor line which is connected to said central conductor and an outer shielding which is connected to said strips.

Claim 14

A nuclear magnetic resonance magnetometer of the spin-coupling type comprising: two samples located close to each other in the magnetic field to be measured and containing the same atomic nuclei having non-zero magnetic moment and kinetic moment and a paramagnetic substance having at least an electron resonance line saturable by a VHF electromagnetic field; two axially aligned identical coils each associated with a respective one of said samples; means for producing an electromagnetic field coupled with said samples to saturate an electron resonance line of one of the samples so as to produce an increase in energy absorption at the resonant frequency of the atomic nuclei and an electron resonance line of the other sample so as to produce an energy emission at said resonant frequency of the atomic nuclei; a resonant circuit for sustaining the nuclear magnetic resonance of said nuclei, comprising a low frequency amplifier and at least said two coils each electromagnetically coupled with one of said samples and connected to said amplifier; and means for measuring the resonance frequency in said loop; wherein the means for producing an electromagnetic field at the electron resonance frequency comprise a single VHF oscillator, a resonant cavity, and a coaxial cable, said cavity having a central conductor disposed along the common axis of the coils and a shielding which encloses the samples and the coils and is formed by longitudinal strips of highly electrically conductive metal and said coaxial cable having an inner conductor line which is connected to said central conductor and an outer shielding which is connected to said strips.