Mass spectrometer

1. An electron capture dissociation device comprising:

a linear ion trap having linear multipole electrodes applied with a radio frequency electric field and wall electrodes that are arranged on both ends in an axis direction of the linear multipole electrodes, said wall electrodes being provided with holes on the axis of the linear multipole electrodes and applied with a direct-current voltage to generate a wall electric field;

a cylindrical magnetic field-generating unit that generates a magnetic field containing the same axis as the axis of the linear multipole electrodes and surrounds the linear ion trap; and

an electron source arranged opposite to the linear multipole electrodes with one of the wall electrodes sandwiched in-between to pass electrons generated from the electron source towards the linear multipole electrodes,

wherein an electron generation site of the electron source is placed inside the magnetic field generated by the magnetic field-generating unit,

wherein ions are introduced and ejected from the wall electrode not on the side of the electron source.

2. The electron capture dissociation device according to claim 1 , wherein the electron generation site of the electron source is placed on the edge surface of the cylindrical magnetic field-generating unit or on the inside therefrom.

3. The electron capture dissociation device according to claim 1 , wherein lines of magnetic force of the magnetic field are arranged to pass through the other wall electrode not on the side of the electron source.

4. The electron capture dissociation device according to claim 3 , further comprising an ammeter connected to detect an electron current flowing into the wall electrode not on the side of the electron source.

5. The electron capture dissociation device according to claim 1 , wherein a quadrupole deflector is provided adjacently to the wall electrode not on the side of the electron source.

6. The electron capture dissociation device according to claim 5 , wherein an ion guide is provided between the wall electrode not on the side of the electron source and the quadrupole deflector.

7. The electron capture dissociation device according to claim 6 , wherein the length of the ion guide allows the intensity of a magnetic field generated from electron capture dissociation reaction section decays to a level equal to or lower than 1 mT.

8. The electron capture dissociation device according to claim 1 , wherein the magnetic field-generating unit is a permanent magnet.

9. The electron capture dissociation device according to claim 1 , wherein the magnetic field-generating unit is an electromagnet.

10. The electron capture dissociation device according to claim 1 , wherein the magnetic field-generating unit is a solenoid placed outside vacuum.

11. The electron capture dissociation device according to claim 1 , wherein the electron source is a coiled filament.

12. The electron capture dissociation device according to claim 11 , wherein an electron-drawing electrode is provided between the electron source and the wall electrode.

13. The electron capture dissociation device according to claim 12 , wherein the electron-drawing electrode has a flat plate structure with an opening or a mesh structure.

14. The electron capture dissociation device according to claim 12 , wherein the electron-drawing electrode is formed of rhenium, molybdenum, or an alloy of rhenium and molybdenum.

15. The electron capture dissociation device according to claim 12 , wherein an electron lens electrode to accelerate electrons is further provided between the electron source and the electron-drawing electrode.

16. The electron capture dissociation device according to claim 12 , wherein the electron-drawing electrode is coated with fine graphite particles.

17. The electron capture dissociation device according to claim 11 , wherein the linear ion trap has a gas chamber formed in the inside of the cylindrical magnetic field-generating unit.

18. The electron capture dissociation device according to claim 17 , wherein gas introduced into the gas chamber is a rare gas and the inside of the gas chamber is set to from 0.1 Pa to 10 Pa.

19. The electron capture dissociation device according to claim 18 , wherein electron energy of the electron source is from 2 eV to 10 eV.

20. The electron capture dissociation device according to claim 11 , further comprising an electrode that captures electrons passing through the hole of the wall electrode placed close to the electron source and detects current thereof.

21. The electron capture dissociation device according to claim 1 , wherein electron energy of the electron source is from 0 eV to 13 eV.

22. An electron capture dissociation device, comprising:

a linear ion trap having linear multipole electrodes applied with a radio frequency electric field and wall electrodes that are arranged on both ends in the axis direction of the linear multipole electrodes, provided with holes on the axis of the linear multipole electrodes, and applied with a direct-current voltage to generate a wall electric field;

a cylindrical magnetic field-generating unit that generates a magnetic field containing the same axis as the axis of the linear multipole electrodes and surrounds the linear ion trap; and

an electron source arranged opposite to the linear multipole electrodes with sandwiching one of the wall electrodes, wherein electron generation site of the electron source is placed inside the magnetic field generated by the magnetic field-generating unit,

wherein lines of magnetic force of the magnetic field are arranged to pass through the other wall electrode not on the side of the electron source, and

wherein an ammeter to detect an electron current flowing into the wall electrode not on the side of the electron source is connected.

23. An electron capture dissociation device, comprising:

a linear ion trap having linear multipole electrodes applied with a radio frequency electric field and wall electrodes that are arranged on both ends in the axis direction of the linear multipole electrodes, provided with holes on the axis of the linear multipole electrodes, and applied with a direct-current voltage to generate a wall electric field;

a cylindrical magnetic field-generating unit that generates a magnetic field containing the same axis as the axis of the linear multipole electrodes and surrounds the linear ion trap; and

an electron source arranged opposite to the linear multipole electrodes with sandwiching one of the wall electrodes, wherein electron generation site of the electron source is placed inside the magnetic field generated by the magnetic field-generating unit,

wherein a quadrupole deflector is provided adjacently to the wall electrode not on the side of the electron source, and

further wherein an ion guide is provided between the wall electrode not on the side of the electron source and the quadrupole deflector, and

further wherein the length of the ion guide is a length that allows the intensity of a magnetic field generated from electron capture dissociation reaction section decays to a level equal to or lower than 1 mT.

24. An electron capture dissociation device, comprising:

a linear ion trap having linear multipole electrodes applied with a radio frequency electric field and wall electrodes that are arranged on both ends in the axis direction of the linear multipole electrodes, provided with holes on the axis of the linear multipole electrodes, and applied with a direct-current voltage to generate a wall electric field;

a cylindrical magnetic field-generating unit that generates a magnetic field containing the same axis as the axis of the linear multipole electrodes and surrounds the linear ion trap; and

an electron source arranged opposite to the linear multipole electrodes with sandwiching one of the wall electrodes, wherein electron generation site of the electron source is placed inside the magnetic field generated by the magnetic field-generating unit,

wherein the electron source is a coiled filament, and

further wherein an electron-drawing electrode is provided between the electron source and the wall electrode, and

further wherein the electron-drawing electrode is coated with fine graphite particles.

25. An electron capture dissociation device, comprising:

a linear ion trap having linear multipole electrodes applied with a radio frequency electric field and wall electrodes that are arranged on both ends in the axis direction of the linear multipole electrodes, provided with holes on the axis of the linear multipole electrodes, and applied with a direct-current voltage to generate a wall electric field;

a cylindrical magnetic field-generating unit that generates a magnetic field containing the same axis as the axis of the linear multipole electrodes and surrounds the linear ion trap; and

an electron source arranged opposite to the linear multipole electrodes with sandwiching one of the wall electrodes, wherein electron generation site of the electron source is placed inside the magnetic field generated by the magnetic field-generating unit,

wherein the electron source is a coiled filament, and

further wherein an electrode that captures electrons passing through the hole of the wall electrode placed on the side opposite to the electron source and detects a current thereof is provided.