MASS SPECTROMETER FOR DETECTING LEAKAGES VIA A TRACER GAS
The present invention relates to a mass spectrometer ( 10 ) for detecting leakages via a tracer gas, said spectrometer ( 10 ) comprising:—an ionising means ( 3 ) intended to ionise said tracer gas;—at least one magnetic-field source ( 501 ) that generates a magnetic field (I) that is dependent on the electric current I supplied to said source ( 501 ) and that is intended to sort ionised elements;—a means ( 7 ) for detecting said tracer gas once ionised; characterized in that said spectrometer comprises a means (II) for adjusting the magnetic field, said adjusting means being configured to allow at least two separate adjustments, said adjustments having different sensitivities.
1 . Mass spectrometer ( 10 ) for detecting leakages via a tracer gas, said spectrometer ( 10 ) comprising:
an ionisation means ( 3 ) intended to ionise said tracer gas;
at least one magnetic field source ( 501 ) generating a magnetic field {right arrow over (B)} dependent on the electric current I supplying said source ( 501 ) intended for sorting the ionised elements;
a means ( 7 ) for detecting said ionised tracer gas;
characterised in that said spectrometer comprises a means ( 400 ) for adjusting the magnetic field {right arrow over (B)} generated by said source ( 501 ), said adjustment means ( 400 ) being configured to allow at least two distinct adjustments, said adjustments having different sensitivities.
2 . Mass spectrometer according to the preceding claim , characterised in that said adjustment means comprises a pre-adjustment and a fine adjustment.
3 . Mass spectrometer according to any one of the preceding claims , characterised in that one of the adjustments makes it possible to establish a nominal magnetic field {right arrow over (B 0 )}, while the other adjustment makes it possible to generate a variation in magnetic field Δ{right arrow over (B)} around the value of the nominal magnetic field {right arrow over (B 0 )}.
4 . Mass spectrometer according to any one of the preceding claims , characterised in that said magnetic-field source ( 501 ) comprises an electromagnet.
5 . Mass spectrometer according to any one of the preceding claims , characterised in that said adjustment means comprises at least two adjustment commands ( 401 and 403 ), a combinatorial circuit ( 407 ) configured to combine the values of said at least two commands ( 401 and 403 ), and a circuit ( 405 ) for controlling the current I circulating in said magnetic field source ( 501 ).
6 . Mass spectrometer according to the preceding claim , characterised in that said at least two adjustment commands are electrical quantities V 1 et V 2 , such as voltages.
7 . Mass spectrometer according to the preceding claim , characterised in that the magnetic field {right arrow over (B)} depends on the values of the electrical quantities V 1 and V 2 of said at least two adjustment commands.
8 . Mass spectrometer according to claim 5 , characterised in that the combinatorial circuit ( 407 ) comprises:
a plurality of resistors R 1 , R 2 , R 3 and R 4 ;
an operational amplifier AO 1 associated with said resistors R 1 , R 2 , R 3 and R 4 to form a non-inverting summing circuit.
9 . Mass spectrometer according to claim 5 , characterised in that the control circuit ( 405 ) comprises an operational amplifier AO 2 associated with a grounding resistor (R S ) and with a transistor (T1), the assembly forming a circuit of the voltage to current converter type.
10 . Mass spectrometer according to any one of the preceding claims , characterised in that it comprises N adjustment commands and/or N magnetic field sources, where N is an integer greater than or equal to 3.
11 . System for detecting leakages via tracer gas, characterised in that it comprises a mass spectrometer ( 10 ) according to any one of the preceding claims .