Electrostatic suppression of ion feedback in a microchannel plate photomultiplier
AssigneeBurle Technologies, Inc.
InventorJeffrey DeFazio
Life of this patent
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Abstract
A photomultiplier tube having an ion suppression electrode positioned between a photocathode and an electron multiplying device in the photomultiplier tube is disclosed. The ion suppression electrode includes a grid that is configured to provide sufficient rigidity to avoid deformation during operation of the photomultiplier tube. The photomultiplier tube also includes a source of electric potential connected to the electron multiplying device and to the ion suppression electrode to provide a first voltage to the second electrode and a second voltage to the suppression grid electrode wherein the second voltage has a magnitude equal to or greater than the magnitude of the first voltage. A method of making the photomultiplier and a method of using it are also disclosed.
Claims15
A photomultiplier tube comprising:
- a photocathode having a first surface for receiving light and a second surface opposite the first surface from which electrons are emitted in response to light that is incident on the first surface;
- an electron multiplying device positioned in spaced relation to said photocathode, said electron multiplying device having an electron receiving side that faces the second surface of said photocathode and an electron emission side opposite the electron receiving side, said electron multiplying device being positioned such that the electron receiving side is located at a preselected distance from the second surface of said photocathode;
- a first electrode operatively connected to the electron receiving side of said electron multiplying device;
- a second electrode operatively connected to the electron emission side of said electron multiplying device;
- an ion suppression electrode positioned between said photocathode and said electron multiplying device and spaced therefrom, said ion suppression electrode comprising a grid that is configured to provide sufficient rigidity to avoid deformation during operation of the photomultiplier tube;
- and
- a source of electric potential connected to said second electrode and to said ion suppression electrode, said electric potential source being adapted to provide a first voltage to said second electrode and a second voltage to said suppression grid electrode wherein the second voltage has a magnitude equal to or greater than the magnitude of the first voltage.
A method of making a photomultiplier comprising the steps of:
- providing a photocathode having a first surface for receiving light and a second surface opposite the first surface from which electrons are emitted in response to light that is incident on the first surface;
- providing an electron multiplying device in spaced relation from said photocathode, wherein said electron multiplying device has an electron receiving side that faces the second surface of said photocathode and an electron emission side opposing the electron receiving side, wherein said electron multiplying device is positioned such that the electron receiving side is located at a preselected distance from the second surface of said photocathode;
- providing an ion suppression electrode between said photocathode and said electron multiplying device, said ion suppression electrode consisting of a fine mesh grid;
- energizing the electron receiving surface of the electron multiplying device with a first voltage;
- energizing the electron emission surface of the electron multiplying device with a second voltage that is greater in magnitude than the first voltage;
- and
- energizing the suppression electrode with a third voltage having a magnitude that is equal to or greater than the magnitude of the second voltage.
Dependencies are inferred from the claim text.