Radiant energy – Ionic separation or analysis – Static field-type ion path-bending selecting means
Patent
1985-11-01
1987-02-17
Anderson, Bruce C.
Radiant energy
Ionic separation or analysis
Static field-type ion path-bending selecting means
250297, 250281, 313161, H01J 4928
Patent
active
046441611
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to magnetic deflection mass spectrographs which are more compact and more sensitive than existing devices.
BACKGROUND OF THE INVENTION
Magnetic deflection spectrographs are based on deflecting a narrow beam of ions in a magnetic field. In a given field, the angle of deflection varies by .sqroot.(1/mV), where V is the accelerating voltage. The deflected beam is received by a narrow slot located at a distance: the deflection angle is thus accurately defined, and for each value of V the slot selects ions having the corresponding mass m, where mV=C. The resolution naturally increases with the distance of the selector slot from the deflecting field. The drawbacks of this type of apparatus are obvious: high resolution requires considerable bulk. Further, the use of a narrow beam of ions greatly reduces the sensitivity of the system.
SUMMRY OF THE INVENTION
In the new invention, the separator device is circularly symmetrical: the ions are injected radially in the mid plane of the separator device all around a circular slot: the number of ions injected may thus be very large, and because of the symmetry of the system, these ions are all presented under initial conditions which are identical.
A first magnetic field created by a pair of ring-shaped permanent magnets produces a first separation; ions of different masses describe circular trajectories of different radii and are recovered, under differing initial conditions, by a second field (which may be magnetic or electrostatic) which selectively collects the ions or accentuates their separation prior to collection by a third field. Such a device makes it possible to obtain good resolution and high sensitivity while confining the trajectories to a reduced volume of space.
The ionizing and ion injection device is constituted as follows: a circular heated filament situated in the mid plane of the system emits electrons which are accelerated by a radial electrostatic field; these electrons are thus injected, still in the mid plane, into the magnetic field produced by a pair of ring shaped magnets as in the separator device. The envelope of the circular electron trajectories is a large circle of radius r. Most of the ionizing shocks take place in the immediate vicinity of this circle. A second radial electrostatic field applied beyond the circle r extracts and accelerates the ions formed under the variable voltage V. In this ionizing device, the magnetic field plays three roles; firstly it serves as a barrier to the electrons and prevents them from penetrating into the variable potential region where the ions are accelerated; secondly, a large portion of the electron trajectories is in practice the same as the circle of the envelope, the ions are thus mostly formed in the immediate vicinity of the accelerating field but in a region which is still an equipotential region and they thus have the same initial kinetic energy; and thirdly most of the ions emitted in all directions at speeds corresponding to thermal agitation in a gas are directed towards the acceleration region with the magnetic field acting as an attractive field without modifying the kinetic energy of the ions.
The invention will be better understood with reference to particular embodiments given by way of example and shown in the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic plane view of the ion source of a mass spectrograph in accordance with a first embodiment of the invention;
FIG. 2 is a section on line II--II of FIG. 1;
FIG. 3 is a diagrammatic view from above of the analysis system of a mass spectrograph mentioned with reference to FIGS. 1 and 2;
FIG. 4 is a section on line IV--IV of FIG. 3;
FIG. 5 is a diagrammatic view from above of a variant mass spectrograph;
FIG. 6 is a section view on line VI--VI of FIG. 5,
FIG. 7 is a view from above of a variant embodiment of a mass spectrograph;
FIG. 8 is a section view on line VIII--VIII of FIG. 7;
FIG. 9 is a diagrammatic view of a variant embodim
Anderson Bruce C.
Berman Jack I.
Compagnie Industrielle des Telecommunications Cit-Alcatel
LandOfFree
Mass spectrograph does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mass spectrograph, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mass spectrograph will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1938990