Patent ID: 7538320

Claim:
An ion detection device comprising: a chamber having an inlet and configured to receive ions through the inlet; a shutter provided in the chamber opposite the inlet and configured to allow or prevent the ions to pass the shutter, the shutter having first and second shutter elements; a collector provided in the chamber opposite the shutter and configured to collect ions passed through the shutter; a processing unit electrically connected to the first and second shutter elements and configured to apply, during a first predetermined time interval, a first voltage to the first shutter element and a second voltage to the second shutter element, the second voltage being lower than the first voltage such that ions from the inlet enter a volume defined by the first and second shutter elements, and during a second predetermined time interval, a third voltage to the first shutter element, higher than the first voltage, and a fourth voltage to the second shutter element, the third voltage being higher than the fourth voltage such that ions that entered the volume are compressed as the ions exit the volume and new ions coming from the inlet are prevented from entering the volume; and the processing unit being electrically coupled to the collector and configured to detect the compressed ions based at least on a current received from the collector and produced by the ions collected by the collector.