Mass spectrometer for detecting leakages via a tracer gas

A mass spectrometer for detecting leakages via a tracer gas, said spectrometer comprising:

• an ionisation means intended to ionise said tracer gas;
• at least one magnetic field source generating a magnetic field {right arrow over (B)} dependent on an electric current I supplying said source intended for sorting the ionised elements;
• a means for detecting said ionised tracer gas;
• characterised in that said spectrometer comprises a means for adjusting the magnetic field {right arrow over (B)} generated by said source, said adjustment means being configured to allow at least two distinct adjustments, said adjustments having different sensitivities, wherein said adjustment means comprises at least two adjustment commands, a combinatorial circuit configured to combine values of said at least two adjustment commands, and a circuit for controlling the current I circulating in said magnetic field source,
• wherein the combinatorial circuit comprises:
• a plurality of resistors R1, R2, R3 and R4;
• and
• an operational amplifier AO1 associated with said plurality of resistors R1, R2, R3 and R4 to form a non-inverting summing circuit,
• wherein the circuit for controlling the current I comprises an operational amplifier AO2 associated with a grounding resistor (RS) and with a transistor (T1) to form a voltage to current converter circuit,
• wherein the respective values of each resistor of the plurality of resistors R1, R2, R3 and R4, are such that R1=R3=R4=R, and R2=kR, and
• wherein k is a constant greater than 1.