Magnetic ion trap mass spectrometer using such a trap

An ion trap vacuum comprising an enclosure sealed treatment (4) and a permanent magnet (30) delimiting a cavity (32) and creating a homogeneous magnetic field oriented (B) in said cavity (32), said enclosure (4) disposed in said cavity (32) and involves a confinement cell (8; 50) quecomprende at least two trapping electrodes (10) parallel to each other and perpendicular to said magneticoorientado field (B), said electrodes trap (10) connectable to a voltage generator (12), characterized in that it comprises at least one magnet (30) permanently shaped hollow cylinder, structured according cylinder structure type Halbach, in order to generate magneticopermanente said field (B) and oriented perpendicularly homogeneous longitudinal axis (XX ') of the cavity (32) dichoiman (30).