Vacuum module and vacuum apparatus and method for regeneration of a volume getter vacuum pump

Abstract

Method for the regeneration of a volume getter pump in a vacuum apparatus with a volume getter pump and an ion getter pump where the operating voltage of the ion getter pump is reduced, the current through the ion getter pump is recorded for determination of the pressure in the vacuum apparatus and then a heating element of the NEG is controlled as a function of the current of the ion getter pump for the purpose of heating the NEG material.

Claims

1. A method for the regeneration of a volume getter pump (NEG) in a vacuum apparatus with the NEG and an ion getter pump, where an operating voltage of the ion getter pump is reduced to a voltage at which no effective pumping is performed by the ion getter pump but the ion getter pump continues to generate a pressure-dependent current, the pressure-dependent current through the ion getter pump is recorded for determination of a pressure in the vacuum apparatus, and a heating element of the NEG is controlled as a function of the pressure-dependent current through the ion getter pump for the purpose of heating an NEG material of the NEG while maintaining the operating voltage of the ion getter pump at the voltage at which no effective pumping is performed by the ion getter pump but the ion getter pump continues to generate the pressure-dependent current.

2. The method in accordance with claim 1, where the operating voltage is reduced to less than 5 kV.

3. The method in accordance with claim 1, where the heating element is switched off if the pressure-dependent current recorded through the ion getter pump corresponds to a pressure which lies above a first pre-set pressure.

4. The method in accordance with claim 3, where the heat output of the heating element is increased if the pressure-dependent current recorded through the ion getter pump corresponds to a pressure which lies below a second pre-set pressure.

5. The method in accordance with claim 4, where the first pre-set pressure and the second pre-set pressure corresponds to 10.sup.?5 mbar.

6. A vacuum apparatus with a volume getter pump (NEG) and an ion getter pump, where the NEG and the ion getter pump are directly connected, where the NEG and the ion getter pump are connected to a control unit, and where the control unit is configured to: reduce an operating voltage of the ion getter pump to a voltage at which no effective pumping is performed by the ion getter pump but the ion getter pump continues to generate a pressure-dependent current, record the pressure-dependent current through the ion getter pump to determine a pressure in the vacuum apparatus; and control a heating element of the NEG as a function of the pressure-dependent current of the ion getter pump for the purpose of heating an NEG material of the NEG while maintaining the operating voltage of the ion getter pump at the voltage at which no effective pumping is performed by the ion getter pump but the ion getter pump continues to generate the pressure-dependent current.

7. A vacuum apparatus with a volume getter pump (NEG) and an ion getter pump, where the NEG and the ion getter pump are arranged separately from each other in the vacuum apparatus, where the NEG and the ion getter pump are connected to a control unit, and where the control unit is configured to: reduce an operating voltage of the ion getter pump to a voltage at which no effective pumping is performed by the ion getter pump but the ion getter pump continues to generate a pressure-dependent current, record the pressure-dependent current through the ion getter pump to determine a pressure in the vacuum apparatus; and control a heating element of the NEG as a function of the pressure-dependent current of the ion getter pump for the purpose of heating an NEG material of the NEG while maintaining the operating voltage of the ion getter pump at the voltage at which no effective pumping is performed by the ion getter pump but the ion getter pump continues to generate the pressure-dependent current.

8. The method in accordance with claim 1, where the operating voltage is reduced to less than 3 kV.

9. The method in accordance with claim 1, where the operating voltage is reduced to less than 1 kV.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained below in greater detail on the basis of a preferred embodiment with reference to the attached Drawings.

(2) The Drawings show as follows:

(3) FIG. 1: a first embodiment of the pump module according to the invention,

(4) FIG. 2: a flow chart of the method according to the invention and

(5) FIG. 3: a diagrammatic representation of the correlation between the current determined by the ion getter pump and the regeneration temperature of the NEG according to the present method.

DETAILED DESCRIPTION

(6) The pump module 10 according to the invention has a flange 12 with a first side 14 and a second side 16, which lies opposite the first side. If the flange 12 is connected to a vacuum apparatus (not shown), the first side 14 faces the vacuum apparatus and is in particular exposed to the vacuum created inside the vacuum apparatus. The second side 16 is exposed to an atmospheric pressure and is arranged outside the vacuum apparatus. With the aid of known means such as screws and seals, the flange 12 can be connected to the vacuum apparatus in a vacuum-tight manner.

(7) An ion getter pump 18 is connected to the first side 14 of the flange 12. A volume getter pump (NEG) 20 is arranged on that side of the ion getter pump 18 opposite to the flange 12 side. Flange 12 and NEG 20 are thus arranged at opposite ends of the ion getter pump. This means that NEG 20 is not directly connected to the flange 12, but rather indirectly by means of the ion getter pump 18. Thus, in installed state, ion getter pump 18 and NEG 20 protrude into the vacuum apparatus and are so arranged therein to pump gases.

(8) The flange 12 further possesses a common lead-through 22, by means of which the high voltage for operation of the ion getter pump 18 as well as the low voltage for the heating element for regeneration of the NEG are led through. This means that only one lead-through is necessary, so that the number of potential leaks of the ultrahigh vacuum apparatus can be reduced.

(9) The diameter of the flange 12 can be kept small by virtue of the stacked or serial structure of the NEG 20, ion getter pump 18 and flange 12, since the diameter of the flange or the diameter of the flange face 24, which is situated directly within the vacuum, corresponds exactly to, or is slightly greater than, the base area of the ion getter pump 18 or NEG 20. Thus, on installation, NEG 20 and ion getter pump 18 are introduced via the flange opening and are attached securely to the vacuum apparatus by attachment of the flange 12 to the vacuum apparatus.

(10) With the method according to the invention as represented in FIG. 2, in a first Step S01 the operating voltage of the ion getter pump is reduced. In this case there is no reduction to 0, nor is the supply voltage to the ion getter pump switched off. Rather, there is simply a reduction in the operating voltage of the ion getter pump, so that effectively there is no longer any pumping action of the ion getter pump. The operating voltage or voltage between the cathode and anode of the ion getter pump may in that case amount to 1 kV for example. At such an operating voltage the current through the ion getter pump is proportional to the pressure inside the vacuum apparatus to which the ion getter pump and also the NEG are connected. In a second Step S02 the current through the ion getter pump is recorded and owing to the proportionality which exists is used for determination of the pressure within the vacuum apparatus. In a third Step S03 of the method according to the invention, a heating element of the NEG 20 is controlled in dependence on the current of the ion getter pump, which corresponds to the pressure inside the vacuum apparatus, for the purpose of bakeout and regeneration of the NEG material.

(11) FIG. 3 is a diagrammatic representation of the correlation between the current, which is determined by the ion getter pump and which corresponds to the pressure inside the vacuum apparatus, and the bakeout temperature of the NEG material for regeneration of the NEG material.

(12) In FIG. 3, the pressure or the current of the ion getter pump is plotted on the x-axis against the y-axis, which corresponds to the temperature of the heating element. Up to a first pressure 40, which lies for example at 10.sup.?5 mbar or 10.sup.?6 mbar, no heating of the NEG material occurs, as this could result in destruction of the NEG material. If however a pressure is present which is lower than the threshold value, bakeout and thus regeneration of the NEG material occurs, in which case as the pressure falls there is a higher temperature of the heating element of the NEG, so that faster regeneration of the NEG material can be achieved. If for example at a first pressure 40 there is a first bakeout temperature of 42, then at a pressure lower than the first pressure there is a second bakeout temperature 44, which is higher than the first bakeout temperature 42 of the heating element of the NEG 20. In that case the correlation between pressure and bakeout temperature must be non-linear, as diagrammatically illustrated in FIG. 3, but may follow any functional correlation and is adjusted to the application in question.

(13) Consequently, a method is proposed whereby regeneration of an NEG material in an NEG is reliably, securely and efficiently brought about by utilisation of an existing ion getter pump.

(14) Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

(15) Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.