Seiko Instruments & Electronics Ltd.

Fumio Watanabe

Masao Miyamoto

Yoshiaki Hara

Takao Ito

Shojiro Komaki

Yasuo Kusumoto

Syojiro Komaki

A quadrupole mass spectrometer generates a stream of ionized particles which are modulated by an AC voltage and transmitted through a quadrupole analyzer to a detection unit. The detection unit detects at a collector electrode thereof a modulated ion current which is fed to a phase detector. The phase detector synchronizes the modulated ion current with a signal of known frequency to produce a DC voltage representative of the level of the modulated ion current. By modulating the ionized particles with the AC voltage, the S/N ratio is improved and adverse effects of external noise are diminished.

AC-modulation quadrupole mass spectrometer

A double grid anode is characterized in that said anode is comprised of a first cage-like anode made of a metal grid or wire gauze that permits that passage of electrons and that has an open end, a second anode which also consists of a metal grid or wire gauze located at the open end side of said first anode, a hot-cathode filament arranged around the outer periphery of said first anode, and an ion-extraction electrode which faces said anode.

Electron-impact type of ion source with double grid anode

Growing community of inventors

Fukushima, Japan

Fumio Watanabe