Optimized Electromagnetic Field On Side-On FT-ICR Mass Spectrometers

A method for stabilizing the magnetic field applied to charged particles in a side-on injection Penning trap, comprising:

• applying a quadrupole electric field to a cylindrical gap between a first set of two or more concentric circular or semi-circular electrodes and a second set of two or more concentric circular or semi-circular electrodes using the first set of electrodes and the second set of electrodes, wherein the first set of electrodes is printed on a first printed circuit board and the second set of electrodes is printed on a second printed circuit board, wherein the second printed circuit board is placed in parallel with the first printed circuit board so that the second set of electrodes faces and is coaxial with the first set of electrodes, and wherein the space between the first set of electrodes and the second set of electrodes is the cylindrical gap used to trap charged particles;
• applying a first magnetic field to the cylindrical gap that is coaxial with the cylindrical gap using at least one permanent magnet, wherein the at least one permanent magnet that is placed coaxially with the first set of electrodes and the second set of electrodes but outside of the cylindrical gap and wherein the effects of the first magnetic field and the quadrupole electric field combine to trap charged particles in the cylindrical gap that are injected in a direction perpendicular to the first magnetic field;
• applying a second magnetic field to the cylindrical gap that is coaxial with the cylindrical gap using at least one solenoid coil electrically connected to a current source, wherein the current source supplies current to the at least one solenoid coil to produce the second magnetic field and wherein the at least one solenoid coil is placed coaxially with the cylindrical gap, but outside of the cylindrical gap;
• measuring a combined magnetic field that is a combination of the first magnetic field and the second magnetic field using at least one magnetic sensor placed in or on the first printed circuit board within the first set of electrodes;
• and
• stabilizing the combined magnetic field using feedback control circuitry electrically connected to the at least one magnetic sensor and the current source by repeatedly over time receiving the measurement of the at least one magnetic sensor and in response adjusting the current of the current source to increase or decrease the second magnetic field in order to maintain the combined magnetic field at a constant value.

A side-on injection Penning trap that includes two sets of printed circuit board electrodes with radial dimensions that are optimized to apply a quadrupole field to charged particles, comprising:

• a first printed circuit board on which is printed a first set of two or more concentric circular or semi-circular electrodes;
• a second printed circuit board on which is printed a second set of two or more concentric circular or semi-circular electrodes that correspond in size and shape to the first set of electrodes, wherein the second printed circuit board is placed in parallel with the first printed circuit board so that the second set of electrodes faces and is coaxial with the first set of electrodes, wherein the space between the first set of electrodes and the second set of electrodes is a cylindrical gap used to trap charged particles, wherein the cylindrical gap has a length d, wherein the first set of electrodes and the second set of electrodes each includes a central disk electrode with a radius of 1.1 d, a first concentric ring or segmented ring electrode of radius 1.9 d, and a second concentric ring or segmented ring electrode of radius 2.4 d, and wherein the first set of electrodes and the second set of electrodes apply a quadrupole electric field to the cylindrical gap;
• and
• at least one permanent magnet that is placed coaxially with the first set of electrodes and the second set of electrodes but outside of the cylindrical gap that applies a first magnetic field to the cylindrical gap that is coaxial with the cylindrical gap, wherein the effects of the first magnetic field and the quadrupole electric field combine to trap charged particles in the cylindrical gap that are injected in a direction perpendicular to the first magnetic field.