Precision magnetic field monitoring in high radiation environments
View Patent ↗A high-precision magnetometer based on a miniature Penning trap is used to measure high magnetic field strengths with very high accuracy. Due to the high precision of the developed miniature charged particle trap, magnetic field strengths can be measured with an accuracy of 1 part per million or greater, including up to and above 1 part per billion. The charged particle trap has been configured to operate with such precision in environments of high radiation, e.g., 1 MGy or above.
1. A device for measuring magnetic fields in a high radiation field environment, the device comprising:
a charged particle trapping structure comprising two opposing end cap electrodes each on opposite ends of a central ring electrode structure, the opposing electrodes and the ring electrode structure collectively defining an inner chamber, with the inner chamber adapted (i) for generation of charged particles within the inner chamber through ionization of neutral atoms or molecules and adapted for trapping generated charged particles or (ii) for the capture and trapping of externally generated charged particles, in the presence of a magnetic field and a static electric potential created from voltages supplied to the charged particle trapping structure;
a radio frequency generator coupled to the charged particle trapping structure to generate an electric field inside the inner chamber to excite or maintain cyclotron motion of the charged particles within the inner chamber, wherein the charged particle trapping structure is adapted to detect the cyclotron frequency of the charged particles within the inner chamber over an operating environment range of an accumulated radiation dose of 1 MGy or above; and
an electronic detector adapted to determine a value of the detected cyclotron frequency and to determine a magnetic field strength of the magnetic from the cyclotron frequency.
2. The device of claim 1 , wherein the device is adapted to measure the magnetic field strength by measuring the cyclotron frequency of the charged particles within the inner chamber with an accuracy of 10 parts per million or better over the operating environment range of the accumulated radiation dose.
3. The device of claim 1 , wherein the electronic detector comprises:
a radio frequency measurement device; and
a processor connected to the radio frequency measurement device, wherein the processor is configured to analyze a received radio frequency signal and to determine a radio frequency corresponding to the charged particles within the inner chamber, wherein the radio frequency measurement is accurate to 10 parts per million or better over the operating environment range of the accumulated radiation dose.
4. The device of claim 3 , wherein the processor is further configured to convert the cyclotron frequency to a magnetic field strength experienced by the charged particles within the inner chamber.
5. The device of claim 1 , wherein the charged particle trapping structure is a Penning trap.
6. The device of claim 5 , wherein the two opposing end cap electrodes and the ring electrode structure are formed of one or more metals, and wherein the Penning trap comprises isolating material that positions each electrode in the ring electrode structure and between the ring electrode structure and the two opposing end cap electrodes in place, the isolating material being of a one or more ceramics, glass, or other inorganic insulating and highly radiation resistant material.
7. The device of claim 1 , wherein the trapping structure is adapted for generation of electrons that can be introduced into the inner chamber.
8. The device of claim 1 , wherein the trapping structure is adapted for generation of light ions of stable isotopes within the inner chamber.
9. The device of claim 1 , wherein the operating environment radiation range is between 1 MGy and 100 MGy.
10. The device of claim 1 , wherein the operating environment radiation range is above 100 MGy.
11. The device of claim 1 , wherein the charged particle trapping structure is adapted to measure the strength of the magnetic field with an accuracy of 1 parts per million or greater.
12. A method for measuring the strength of a magnetic field, the method comprising:
generating target charged particles within a Penning trap or injecting the target charged particles into the Penning trap;
maintaining the target charged particles within the Penning trap, such that for a given trap radius and trap length, applying a static magnetic field and a quadrupole electric field within the Penning trap maintains the target charged particles within the Penning trap for at least a measurement cycle;
measuring the cyclotron frequency using an image charge resonance detection technique measuring radial motion of the target charged particles; and
determining a field strength of the magnetic field from the cyclotron frequency,
wherein the Penning trap is sized for measuring the field strength with an accuracy of 10 parts per million or greater, over an operating environment radiation range of 1 MGy or above.
13. The method of claim 12 , wherein the image charge resonance detection technique is a Fourier transform-ion cyclotron resonance (FT-ICR) technique.