Granted Patent B2

US 7,491,931 · App. 11/429,371 · Granted Feb 17, 2009

Abstract

Claims (25)

1. An ion source for a mass analyzer comprising:

a first electrode;

a second electrode spaced apart from the first electrode; and

a power source electrically coupled to one or more of the first electrode and the second electrode, the power source comprising:

a power supply circuit having at least one output node coupled through a switch to at least one of the first electrode and the second electrode, the power supply circuit supplying an electric potential to at least one of the first electrode or the second electrode to establish an electric field at a predetermined time; and

a feedback circuit responsive to a DC component and an AC component of an output voltage supplied by the power supply to produce a feedback signal on an output node of the feedback circuit representative of at least one of: (a) a value of the output voltage prior to a charge transfer from a capacitor associated with the power supply to at least one of the first electrode and the second electrode; (b) a value of the output voltage during the charge transfer from the capacitor associated with the power supply to at least one of the first electrode and the second electrode; and (c) a value of the output voltage after the charge transfer from the capacitor associated with the power supply to at least one of the sample support or the first electrode.

2. The ion source of claim 1 , wherein the power source is responsive to the feedback signal to regulate the value of the output voltage.

3. The ion source of claim 1 , wherein the feedback circuit comprises:

a summing circuit to sum the first signal and the second signal to produce a summed signal; and

a difference circuit to determine a difference between the summed signal and the reference signal to produce the feedback signal.

4. The ion source of claim 3 , wherein the feedback circuit further comprises:

a first filter circuit to filter the DC component of the supplied voltage by the power supply; and

a second filter circuit to filter the AC component of the supplied voltage by the power supply.

5. The ion source of claim 4 , wherein the feedback circuit further comprises:

a first divider circuit to divide the DC component of the voltage supplied by the power supply by a first value; and

a second divider circuit to divide the AC component of the voltage supplied by the power supply by a second value.

6. The ion source of claim 5 , wherein the feedback circuit further comprises:

a signal conditioning circuit to produce a rectified output based on the AC component of the voltage supplied by the power supply.

7. The ion source of claim 6 , wherein the feedback circuit further comprises:

a third divider circuit to divide the rectified output of the signal conditioning circuit by a third value.

8. The ion source of claim 7 , wherein the first value for the first divider circuit is substantially equal to a resultant of the second value for the second divider circuit and the third value for the third divider circuit.

9. The ion source of claim 1 , wherein the power source is a high voltage power supply circuit capable of supplying a voltage in the range between about 5,000 volts to about 30,000 volts to a mass spectrometer.

10. The ion source of claim 1 , wherein the first electrode comprises a MALDI sample support.

11. The ion source of claim 1 , wherein the ion source is a virtual ion source for an orthogonal TOF instrument, the first electrode and the second electrode configured to deflect ions at a predetermined time from a first trajectory onto a second trajectory substantially perpendicular to the first trajectory, the second trajectory passing through a TOF region.

12. The ion source of claim 1 , wherein the ion source comprises the exit of a collision cell, the first electrode and second electrode configured to extract ions from the collision cell.

Assignments (9)