Radial flow turbomolecular vacuum pump

Information

  • Patent Grant
  • 6508631
  • Patent Number
    6,508,631
  • Date Filed
    Thursday, November 18, 1999
    25 years ago
  • Date Issued
    Tuesday, January 21, 2003
    22 years ago
Abstract
A radial flow turbomolecular vacuum pump includes a gas inlet, a gas outlet, a rotor, and a stator. The rotor includes a first rotor surface that is positioned in a substantially radial direction. A plurality of blades extends from the first rotor surface in a substantially axial direction. The stator includes a first stator surface that is positioned proximate to the first rotor surface in the substantially radial direction. A first and second plurality of vanes extend from the first stator surface and generally forms an annulus therebetween for receiving the first plurality of blades. A drive shaft is coupled to the rotor and positioned in the substantially axial direction. A motor is coupled to the drive shaft and rotates the rotor relative to the stator. The rotation of the rotor relative to the stator causes gas to be pumped from the gas inlet to the gas outlet in the substantially radial direction.
Description




FIELD OF THE INVENTION




The invention relates generally to the field of vacuum pumps and compressors. In particular, the present invention relates to radial flow turbomolecular vacuum pumps and methods for operating radial flow pumps.




BACKGROUND OF THE INVENTION




Prior art vacuum pumping systems are typically continuous flow compression systems that evacuate gas from a vacuum chamber at low pressure, for example 10


−6


torr, and then compress the gas to atmospheric pressure so that the gas may be discharged to the atmosphere. Such prior art pumping systems would typically include a high vacuum pump, such as a turbomolecular pump or a diffusion pump, capable of evacuating to high vacuum. This pump would be followed by a fore pump such as an oil sealed rotary pump or a diaphragm pump, which would further compress the gas and exhaust the gas to the atmosphere.




Vacuum pumps are used for numerous applications including vacuum based instrumentation, such as mass spectrometers, electron microscopes, and various surface analysis tools that use ion or electron beams. Such vacuum based instruments are typically designed for use in dedicated laboratories because of the size, weight, and service requirements of the vacuum pump and other hardware. Consequently, analysis is typically performed by transporting the material to be analyzed to a dedicated laboratory facility. Unfortunately, not all materials that require analysis can be conveniently transported. There is a significant need for portable vacuum based analysis equipment that can be transported to the location of the analysis.




Attempts to produce portable vacuum based instruments have had only limited success because it is difficult to achieve the required pumping capacity with a compact pump design. Also, some prior art pumping designs, such as diffusion and oil sealed pump designs, are sensitive to operating position and have service requirements that are inconsistent with general requirements for portable pumps. Prior art turbomolecular pumps must have a substantially large axial dimension in order to have acceptable pumping efficiency. Other prior art vacuum pumps, such as diaphragm type pumps, require several compression stages which adds to their size, weight and power requirement.




Many prior art portable instruments use storage-type vacuum pumps. Storage vacuum pumps include ion pumps, getter pumps and sorption pumps. These pumps operate by capturing gas molecules within the pump and storing them. The molecules are stored up to some capacity limit of the pump and then the pump must be discarded or reprocessed, which is both inconvenient and expensive.




Storage-type vacuum pumps have numerous disadvantages. Storage-type vacuum pumps have poor pumping speed for certain gases. They are also difficult to restart after a shutdown. In addition, if the pumps store toxic gases, there is a danger of poisoning the user if the pump malfunctions. Notwithstanding the disadvantages of storage type vacuum pumps, these pumps are only slightly smaller than the compression type pumps.




In addition, laboratory space, especially in the semiconductor industry, is very costly and not easily expandable and reconfigurable. There is also a significant need for compact instruments that reduce the size, weight and service requirements of analysis equipment used in laboratories. In addition, there is a need for compact add-on instruments that do not significantly increase the footprint of existing laboratory equipment so as to avoid reconfiguring a laboratory.




SUMMARY OF THE INVENTION




The present invention relates to compact vacuum pumps that can be used in instrumentation where the application may be portable, hand held or space limited. A principal discovery of the present invention is that an efficient compact turbomolecular vacuum pump can be constructed having a radial flow design where the dimension of the gas flow path in the radial direction is greater than the dimension of the gas flow path in the axial direction.




Accordingly, in one embodiment, the present invention features a radial turbomolecular vacuum pump that includes a gas inlet, a gas outlet, a rotor, and a casing. The rotor includes a first rotor surface that is positioned in a substantially radial direction. A first plurality of blades extends from the first rotor surface in a substantially axial direction. In one embodiment, at least one blade of the first plurality of blades is shaped to increase pumping efficiency. A support ring that reduces deflection due to centrifugal force may be positioned around at least one blade of the plurality of blades. The rotor and at least one blade of the first plurality of blades may be integrally formed from one piece of material.




In one embodiment, the first rotor surface may include at least one cavity that is dimensioned to receive and to retain at least one blade of the first plurality of blades. The at least one blade of the first plurality of blades may include a dovetail and the at least one cavity may be adapted to receive the dovetail. The dovetail may be oriented in a substantially radial direction or in a substantially circumferentially direction.




In one embodiment, the casing includes a first stator surface that is positioned proximate to the first rotor surface in the substantially radial direction. In another embodiment, the stator is separate from the casing. A first and second plurality of vanes extend from the first stator surface and generally forms an annulus therebetween for receiving the first plurality of blades. The annulus may be a groove. At least one vane of the first and second plurality of vanes and the first stator surface may be integrally formed from one piece of material. The stator may include at least one cavity that is dimensioned to receive and retain at least one of the vanes of the first and second plurality of vanes.




In one embodiment, a drive shaft is coupled to the rotor and is positioned in the substantially axial direction. A motor is coupled to the drive shaft and rotates the rotor relative to the stator. In another embodiment, the rotor is directly coupled to the motor without the use of a drive shaft. The rotation of the rotor relative to the casing causes gas to be pumped from the gas inlet to the gas outlet. A fore pump such as a mechanical pump is typically coupled to the gas outlet. In one embodiment, a processor is electrically coupled to the motor and to a pressure sensor that is positioned in fluid communication with the pump. The pressure sensor generates a signal that is proportional to a pressure achieved by the pump and the processor generates a signal that controls a speed of the motor in response to the pressure.




In one embodiment, the vacuum pump further includes a second rotor surface that is positioned in a substantially radial direction. A second plurality of blades extends from the second rotor surface in a substantially axial direction opposite that of the first plurality of blades. A second stator surface is positioned proximate to the second rotor surface in the substantially radial direction. A third and fourth plurality of vanes extend from the second stator surface and generally forming an annulus therebetween for receiving the second plurality of blades.




In another embodiment, the rotor and stator further comprise a second stage. The second stage includes a rotor surface that is positioned in a substantially radial direction. A plurality of blades extends from the rotor surface in a substantially axial direction. The second stage includes a stator surface that is positioned proximate to the second stage rotor surface in the substantially radial direction. A first and second plurality of vanes extend from the stator surface of the second stator and generally form an annulus therebetween for receiving the plurality of blades.




The present invention also features a method for pumping a gas that includes the step of rotating a plurality of substantially axially disposed blades relative to a first and second plurality of vanes that generally form an annulus therebetween for receiving the first plurality of blades. The relative motion of the plurality of blades and the first and second plurality of vanes causes gas to be pumped in a substantially radial direction from a gas inlet to a gas outlet. The gas may be pumped outwardly or inwardly in a substantially radial direction.




In one embodiment, method for pumping a gas further includes rotating a second plurality of substantially axially disposed blades relative to a third and fourth plurality of vanes that generally form an annulus therebetween for receiving the second plurality of blades. The relative motion of the second plurality of blades and the third and fourth plurality of vanes causes gas to be pumped in a substantially radial direction from a gas inlet to a gas outlet. The gas may be pumped outwardly or inwardly in a substantially radial direction.











BRIEF DESCRIPTION OF THE DRAWINGS




This invention is described with particularity in the appended claims. The above and further advantages of this invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:





FIG. 1

illustrates a prior art turbomolecular pump design;





FIG. 2

illustrates one embodiment of a radial flow turbomolecular vacuum pump of the present invention;





FIG. 3

illustrates an axial view of the rotor used in the radial flow turbomolecular vacuum pump of the present invention;





FIG. 4

illustrates a radial flow turbomolecular vacuum pump according to the present invention having rotor blades extending from two surfaces;





FIG. 5

illustrates an embodiment of a radial flow turbomolecular vacuum pump according to the present invention having a second stage;





FIG. 6

illustrates a sectional view of an embodiment of a radial flow turbomolecular vacuum pump according to the present invention having a spiral groove;





FIG. 7

illustrates a functional block diagram of a compact pumping system that includes a radial flow turbomolecular vacuum pump according to the present invention;





FIG. 8

illustrates an analytic instrument that uses the radial turbomolecular vacuum pump according to the present invention.











DETAILED DESCRIPTION





FIG. 1

illustrates a prior art axial flow turbomolecular pump


10


. The pump


10


includes a rotor


12


having a plurality of axial blades


14


. A plurality of stator vanes


16


is positioned to receive the plurality of axial blades


14


. A motor


15


drives the rotor


12


so that each of the plurality of blades


14


passes though a respective one of the plurality of stator vanes


16


. Compression is achieved in a direction that is substantially parallel to an axial centerline


18


. That is, the dimension of the gas flow path parallel the axial centerline


18


is much greater than the dimension of the gas flow path parallel to a radial centerline


20


. Many stages of rotor blades and stator vanes are required to achieve the necessary compression and pumping speed. Typically prior art pumping speeds in liters/sec are approximately 50 to 1000 l/sec.




Efficient operation of the prior art axial flow turbomolecular pumps are achieved by rotating the rotor


12


at relatively high speed. Typical prior art axial flow turbomolecular pumps are designed to rotate the rotor


12


so that a blade tip speed is approximately 400 m/sec. In order to achieve this blade tip speed with currently available bearings and motors, the rotor diameter is sized to greater than approximately 75 mm. The dimension of the rotor diameter typically sets the minimum diameter for the pump assembly.





FIG. 2

illustrates one embodiment of a radial flow turbomolecular vacuum pump


50


of the present invention. By radial flow we mean that the dimension of the gas flow path parallel to the radial centerline


20


is greater than the dimension of the gas flow path parallel to the axial centerline


18


. The pump


50


includes a gas inlet


52


, a gas outlet


54


, a rotor


56


, and a casing


58


. A sensor may be in fluidic communication with the gas inlet


52


or the gas outlet


54


.




The rotor


56


includes a first rotor surface


62


that is positioned in a substantially parallel direction to the radial centerline


20


. The rotor


56


may be formed from a high strength aluminum alloy. A first plurality of blades


64


extends from the first rotor surface


62


in a substantially parallel direction to the axial centerline


18


. In one embodiment, at least one blade of the first plurality of blades


64


is shaped to increase pumping efficiency. A support ring


63


that reduces deflection due to centrifugal force may be positioned around at least one blade of the plurality of blades. In one embodiment, one side of the rotor comprises a molecular drag pump.




The first plurality of blades


64


can be attached to the rotor


56


by numerous means known in the art. In one embodiment, the rotor


56


and at least one blade of the first plurality of blades


64


is integrally formed from one piece of material. In another embodiment, the blades are mounted onto the rotor. The first rotor surface


62


includes at least one cavity


66


that is dimensioned to receive and to retain at least one blade of the first plurality of blades


64


. The at least one blade of the first plurality of blades


64


may include a dovetail


68


and the at least one cavity


66


may be adapted to receive the dovetail


68


. The dovetail


68


may be oriented in the radial direction or in the circumferential direction.




A stator


59


includes a first stator surface


70


that is positioned proximate to the first rotor surface


62


parallel to the radial centerline


20


. In one embodiment, the stator


59


is formed in the casing


58


. A first and second plurality of vanes


72


extend from the first stator surface


70


and generally form an annulus therebetween for receiving the first plurality of blades


64


. The annulus may be a groove. In one embodiment, a space between at least one blade of the first plurality of blades


64


and the first and second plurality of vanes


72


is approximately 0.2 mm. At least one vane of the first and second plurality of vanes


72


and the first stator surface


70


may be integrally formed from one piece of material. Alternatively, the stator may include at least one cavity that is dimensioned to receive and retain at least one of the vanes.




In one embodiment, a drive shaft


74


is coupled to the rotor


56


and is positioned in the axial direction


18


. A motor


76


is coupled to the drive shaft


74


and rotates the rotor


56


relative to the casing


58


. In another embodiment, the rotor


56


is directly coupled to the motor


76


without the use of a drive shaft. For example, permanent magnets (not shown) can be embedded in the rotor


56


and driven by stator coils (not shown) positioned in the facing surface. Alternatively, magnetic bearings can be used to levitate the rotor


56


.




In one embodiment, the motor is a brushless DC motor and the speed of the motor


76


is approximately 50,000 to 150,000 RPM. The rotation of the rotor


56


relative to the casing


58


causes gas to be pumped radially outward away from the axial centerline


18


or radially inward toward the axial centerline


18


, depending on the sense of rotation, from the gas inlet


52


to the gas outlet


54


.




A fore pump


78


, such as a scroll pump, is typically coupled in series with the gas outlet


54


. A molecular drag pump can also be used. The radial flow turbomolecular vacuum pump


50


and the fore pump


78


connected in series pump gases from a high vacuum chamber attached to the gas inlet


52


and exhaust them through a vent


80


to the


10


atmosphere.




One advantage of the radial flow turbomolecular vacuum pump


50


of the present invention is that the axial dimension of the pump is much less than the axial dimension of prior art axial flow turbomolecular vacuum pumps because the compression is achieved radially. The radial flow turbomolecular vacuum pump


50


of the present invention is particularly efficient for low pumping speeds, less than 50 liters/sec.





FIG. 3

illustrates an axial view of the rotor


56


used in the radial flow turbomolecular vacuum pump


50


of the present invention. The rotor


56


comprises the first rotor surface


62


and the first plurality of blades


64


that extends from the first rotor surface in the axial direction


18


. The first plurality of blades


64


are arranged in corresponding concentric rings


82


. The first and second plurality of vanes (not shown) are arranged in concentric stator rings between the concentric rings


82


of first plurality of blades


64


. The gas flow moves radially from one concentric ring of blades, through a corresponding concentric stator ring and then to the next concentric ring of rotor blades and stator blades. One advantage of the rotor


56


of the present invention is that the rotor


56


can be machined from one side in one machining operation, which reduces the manufacturing cost of the pump


50


.




The first plurality of blades


64


are shaped and positioned to achieve a certain pumping speed, compression, and efficiency. The pitch of each blade of the first plurality of blades


64


generally determines the pumping speed and compression. For example, tilting the blades towards the radial direction


20


, will generally result in a higher pumping speed. Tilting the blades towards the circumferential direction, will result in higher compression, which generally results in lower pumping speed.




In one embodiment, the inner blades (blades closest to the axial centerline


18


) are gradually tilted towards the radial direction for high pumping speed and the outer blades (blades farthest from the axial centerline


18


) are gradually tilted towards the circumferential direction for higher compression. In this embodiment, as the gas is compressed, there is more pumping in the blades furthest from the axial centerline


18


, therefore achieving higher compression.





FIG. 4

illustrates a radial flow turbomolecular vacuum pump


100


according to the present invention having rotor blades extending from two surfaces. The pump


100


is similar to the turbomolecular vacuum pump


50


of FIG.


2


. The pump


100


further includes a second rotor surface


102


that is positioned in the radial direction


20


. A second plurality of blades


104


extends from the second rotor surface


102


in the axial direction


18


opposite that of a first plurality of blades


64


.




A second stator surface


108


is positioned proximate to the second rotor surface


102


in the radial direction


20


. A third and fourth plurality of vanes


110


extend from the second stator surface


108


and generally form an annulus therebetween for receiving the second plurality of blades


104


. The rotation of a rotor


112


relative to a casing


114


causes gas to be pumped radially outward away from the axial centerline


18


or radially toward the axial centerline


18


, depending on the sense of rotation, from a gas inlet


116


to the gas outlet


118


.




In one embodiment, the first


70


and the second stator surface


108


pump in parallel to achieve a higher pump speed. That is, the gas is pumped radially outward or radially inward on both the first


62


and the second rotor surface


102


. In another embodiment, the first


70


and the second stator surface


108


pump in series to achieve increased compression. That is, the gas is pumped radially outward on one of the first


62


and second rotor surface


102


and radially inward on the other of the first


64


and second rotor surface


102


.





FIG. 5

illustrates an embodiment of a radial flow turbomolecular vacuum pump


150


according to the present invention having a first


152


and a second stage


154


. The pump


150


is similar to the turbomolecular vacuum pump


50


of

FIG. 4

, but includes a first


156


and a second rotor


158


, each having a first


62


and a second rotor surface


102


. A first


64


and second plurality of blades


104


extends from the first rotor


156


in the axial direction


18


. A first


64


and second plurality of blades


104


extend from the second rotor


158


in the axial direction


18


. A first


70


and a second stator surface


108


is positioned proximate to the first


62


and the second rotor surface


102


, respectively, in the radial direction


20


. A first and second plurality of vanes


72


extend from the first stator surface


70


and generally form an annulus therebetween for receiving the first plurality of blades


64


. A third and fourth plurality of vanes


110


extend from the second stator surface


108


and generally form an annulus therebetween for receiving the second plurality of blades


104


.




In one embodiment, the first


152


and the second stages


154


are configured to pump in series to achieve increased compression. That is, the gas is pumped radially outward or radially inward, depending on the sense of the rotation, in both the first


152


and second stage


154


. In another embodiment, the first


152


and the second stage


154


are configured to pump in parallel to achieve a higher pumping speed. That is, the gas is pumped radially outward in one stage and radially inward in the other stage. Other embodiments of the turbomolecular vacuum pump the present invention includes more than two stages to achieve additional compression or additional pumping speed.





FIG. 6

illustrates a sectional view of an embodiment of a radial flow turbomolecular vacuum pump


200


according to the present invention. The turbomolecular vacuum pump


200


includes a rotor


202


having a first rotor surface


204


that is positioned in the substantially radial direction


20


. A first plurality of blades


206


extends from the first rotor surface


204


in the substantially axial direction


18


. The rotor


202


includes a second rotor surface


208


that is positioned in the substantially radial direction


20


. The second rotor surface


208


is substantially smooth (i.e. does not have any blading).




The vacuum pump


200


has a casing


210


which includes a first stator surface


212


that is positioned proximate to the first rotor surface


204


in the radial direction


20


. A first and second plurality of vanes


214


extends from the first stator surface


212


and generally forms an annulus therebetweeen for receiving the first plurality of blades


206


. At least one vane of the first and second plurality of vanes


214


and the first stator surface


212


may be integrally formed from one piece of material. The casing


210


may include at least one cavity that is dimensioned to receive and retain at least one of vane of the first and second plurality of vanes


214


.




The casing


210


includes a second stator surface


216


. The second stator surface


216


forms a continuous spiral groove


218


of decreasing area moving toward the axial center line


18


. In one embodiment, the spiral shaped pattern encircles the axial center line


18


of the pump


200


three to five times. The spiral groove


218


acts as a Siegbahn type drag pump, which increases the pressure of the gas as the gas moves along the spiral groove


218


toward to the axial center line


18


.




The vacuum pump


200


has a drive shaft


220


coupled to the rotor


202


and is positioned in the axial direction


18


. A motor


222


is coupled to the drive shaft


220


and rotates the rotor


202


relative to the casing


210


. The rotation of the rotor


202


relative to the casing


210


causes gas to be pumped from a gas inlet


224


to a gas outlet


226


. Gas is pumped from the gas inlet


224


, through the first rotor surface


204


and first stator surface


212


in a radially outward direction. The gas is then pumped along the second stator surface


216


through the spiral groove


218


toward the centerline


18


. The gas is then pumped through to the gas outlet


226


.





FIG. 7

illustrates a functional block diagram of a compact pumping system


250


that includes a radial flow turbomolecular vacuum pump


252


according to the present invention. The system includes a vacuum chamber


254


that is in fluid communication with an input


256


to the radial flow turbomolecular vacuum pump


252


. A first pressure sensor


258


is positioned in a conduit


260


between the vacuum chamber


254


and the turbomolecular vacuum pump


252


. The first pressure sensor


258


generates an electrical signal at an output


259


that is proportional to the pressure at the input


256


to the turbomolecular vacuum pump


252


.




A fore pump


262


is coupled in fluid communication with an exhaust port


264


of the radial flow turbomolecular vacuum pump


252


. The fore pump


262


compresses the gas exhausted from turbomolecular vacuum pump


252


from approximately 0.01 to 1.0 torr and exhausts the gas at atmospheric pressure at an outlet


266


. In one embodiment, the fore pump


262


comprises a scroll pump. In another embodiment, the fore pump


262


comprises a diaphragm sealed rotary pump. Both scroll pumps and diaphragm sealed rotary pump are compatible with the turbomolecular vacuum pump


252


of the present invention and suitable for a compact pumping system because they are relatively small and are oil free.




A second pressure sensor


268


is positioned in a conduit


270


between the exhaust port


264


of the turbomolecular vacuum pump


252


and an input


272


to the fore pump


262


. The second pressure sensor


268


generates an electrical signal at an output


269


that is proportional to the pressure at the input


272


to the fore pump


262


. The compact pumping system


250


may also include other sensors such as temperature, rotor rotation speed, and torque.




An electronic control system


280


controls the operation of the turbomolecular vacuum pump


252


and fore pump


262


. A first


259


and second sensor output


269


is electrically coupled to a first


282


and second electrical input


284


to the electronic control system


280


. The electronic control system


280


has an electrical output


290


that is electrically coupled to the motor


252


that drives the rotor


56


(

FIG. 2

) of the turbomolecular vacuum pump


252


. The electronic control system


280


also has an electrical output


286


that is electrically coupled to the fore pump


262


that controls the speed of the fore pump


262


.




In operation, the electronic control system


280


processes the signals generated by the first


258


and second pressure sensor


268


and produces a signal that controls the speed of the rotor


56


. The speed of the rotor


56


(

FIG. 2

) can be controlled to achieve a certain operating pressure or a certain pumping performance. For example, the control system


280


may be used to adjust the speed of the rotor


56


and the speed of the fore pump


262


to achieve long operating life and operating power consumption.




The compact pumping system


250


provides a high vacuum pumping capability that exhausts gas directly to atmosphere. In one embodiment of the invention, the radial flow turbomolecular pump


252


and fore pump


262


together weigh less than 3 kg and have a volume of less than 2000 cm


3


.





FIG. 8

illustrates an analytic instrument


300


that uses the radial turbomolecular vacuum pump according to the present invention. The instrument


300


includes the compact pumping system


250


of

FIG. 7

that comprises the radial turbomolecular vacuum pump


252


, the fore pump


262


, the electronic control system


280


, and the first


258


and the second pressure sensor


268


.




A vacuum instrument


302


is positioned in fluid communication with the input


256


to the radial flow turbomolecular vacuum pump


252


. The instrument


302


has an electrical output


304


that is coupled to a data acquisition unit


306


. A processor


308


may be connected to the data acquisition unit


306


to analyze and process the data. In one embodiment, the instrument


302


is a compact mass spectrometer and the instruments generates signals that are indicative of the mass of the ions being generated.




A flow control unit


310


is coupled to an input


312


to the instrument


302


. The flow control unit


310


has a sample gas inlet


314


and a carrier gas input


316


. A pump


318


may be coupled in fluid communication with the flow control unit


310


to remove excess gas flow from the flow control unit


310


. In one embodiment, the pump


318


may be a scroll pump or a diaphragm rotary pump.




In one embodiment, a gas separation unit


320


is positioned between the flow control device


310


and the instrument


302


. The gas separation device


320


is used to separate a portion of the sampled gas according to certain characteristics, such as mass range. An output


322


of the flow control unit


310


is positioned in fluid communication with an input


324


of the separation device


320


and an output


326


of the separation device


320


is positioned in fluid communication with the input


312


of the instrument


302


.




The electronic control system


280


is electrically coupled to the flow control unit


310


, the separation device


320


, the instrument


302


, the radial turbomolecular vacuum pump


252


, the fore pump


262


, the processor


308


, and the first


258


and the second pressure sensor


268


. The electronic control system


280


can control the delivery of the sample gas to the instrument


302


, the pressure within the instrument


302


and characteristic of the turbomolecular vacuum pump


252


and the fore pump


262


, such as, operating life and operating power consumption.




Equivalents




While the invention has been particularly shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.



Claims
  • 1. A radial turbomolecular vacuum pump comprising:a) a gas inlet; b) a rotor comprising: i) a first rotor surface that is positioned in a substantially radial direction; and ii) a plurality of blades being in fluid communication with the gas inlet and extending from the first rotor surface in a substantially axial direction, the plurality of blades being arranged in concentric rings of blades and being tilted towards the radial direction; c) a stator comprising: i) a first stator surface that is positioned proximate to the first rotor surface in the substantially radial direction; and ii) a first and a second plurality of vanes extending from the first stator surface, the first and the second plurality of vanes being arranged in concentric stator rings and being disposed between the concentric rings of the plurality of blades and being tilted towards the radial direction; and d) a gas outlet that is in fluid communication with the plurality of blades and the first and the second plurality of vanes, wherein rotation of the rotor relative to the stator causes gas to be pumped radially from the concentric rings of blades through the concentric stator rings and then to the gas outlet.
  • 2. The vacuum pump of claim 1 wherein at least one blade of the plurality of blades and the first rotor surface are integrally formed from one piece of material.
  • 3. The vacuum pump of claim 1 wherein the first rotor surface further comprises at least one cavity that is dimensioned to receive and to retain at least one blade of the plurality of blades.
  • 4. The vacuum pump of claim 3 wherein at least one blade of the plurality of blades further comprises a dovetail and wherein the at least one cavity is adapted to receive the dovetail.
  • 5. The pump of claim 4 wherein the dovetail is oriented in a substantially radial direction.
  • 6. The vacuum pump of claim 4 wherein the dovetails oriented in a substantially circumferential direction.
  • 7. The vacuum pump of claim 1 wherein at least one blade of the plurality of blades is shaped to increase pumping efficiency.
  • 8. The vacuum pump of claim 1 wherein at least one vane of the first and second plurality of vanes and the first stator surface are integrally formed from one piece of material.
  • 9. The vacuum pump of claim 1 wherein the first stator surface includes at least one cavity that is dimensioned to receive and retain at least one of the first and the second plurality of vanes.
  • 10. The vacuum pump of claim 1 further comprising:a) a second rotor surface that is positioned in a substantially radial direction; b) a second plurality of blades extending from the second rotor surface in a substantially axial direction, the second plurality of blades being arranged in concentric rings of blades and being tilted towards the radial direction; c) a second stator surface that is positioned proximate to the second rotor surface in the substantially radial direction; and d) a third and a fourth plurality of vanes extending from the second stator surface, the third and the fourth plurality of vanes being arranged in concentric stator rings and being disposed between the concentric rings of the plurality of blades and being tilted towards the radial direction.
  • 11. The vacuum pump of claim 1 further comprising:a) a drive shaft coupled to the rotor and positioned in the substantially axial direction; and b) a motor coupled to the drive shaft for rotating the rotor relative to the stator.
  • 12. The vacuum pump of claim 11 further comprising a processor that is electrically coupled to the motor and to a pressure sensor, the pressure sensor being in fluidic communication with the vacuum pump and generating a signal proportional to the pressure experienced by the pressure sensor, the processor generating a signal in response to the signal generated by the pressure sensor that controls a speed of the motor.
  • 13. The vacuum pump of claim 1 wherein:a) the rotor further comprises a second stage comprising: i) a rotor surface that is positioned in a substantially radial direction; and ii) a plurality of blades extending from the rotor surface in a substantially axial direction, the plurality of blades being arranged in concentric rings of blades and being tilted towards the radial direction; and b) the stator further comprises a second stage comprising: i) a stator surface that is positioned proximate to the rotor surface in the substantially radial direction; and ii) a first and a second plurality of vanes extending from the stator surface, the first and the second plurality of vanes being arranged in concentric stator rings and being disposed between the concentric rings of the plurality of blades and being tilted towards the radial direction.
  • 14. The vacuum pump of claim 1 wherein the vacuum pump comprises a compressor for compressing the gas.
  • 15. The vacuum pump of claim 1 wherein the stator is formed in a casing containing the vacuum pump.
  • 16. The vacuum pump of claim 1 further comprising a support ring positioned around at least one blade of the plurality of blades, the support ring reducing deflection of the at least one blade due to centrifugal force.
  • 17. The vacuum pump of claim 1 further comprising a mechanical pump that is coupled to the gas outlet.
  • 18. The vacuum pump of claim 1 wherein a dimension of a gas flow path in the substantially radial direction is greater than a dimension of a gas flow path in the substantially axial direction.
  • 19. A radial turbomolecular vacuum pump comprising:a) a gas inlet; b) a rotor comprising: i) a rotor surface that is positioned in a substantially radial direction; and ii) a plurality of blades being in fluid communication with the gas inlet and extending from the rotor surface in a substantially axial direction, the plurality of blades being arranged in concentric rings of blades and being tilted towards the radial direction; c) a casing comprising: i) a first stator surface that is positioned proximate to the first rotor surface in the substantially radial direction; and ii) a first and a second plurality of vanes extending from the first stator surface, the first and the second plurality of vanes being arranged in concentric stator rings and being disposed between the concentric rings of the plurality of blades and being tilted towards the radial direction; d) a gas outlet that is in fluid communication with the plurality of blades and the first and the second plurality of vanes, wherein rotation of the rotor relative to the casing causes gas to be pumped from the gas inlet radially from the concentric rings of blades through the concentric stator rings and then to the gas outlet; and e) a fore pump coupled to the gas outlet.
  • 20. The radial turbomolecular vacuum pump of claim 19 wherein a dimension of a gas flow path in the substantially radial direction is greater than a dimension of a gas flow path in the substantially axial direction.
  • 21. The radial turbomolecular vacuum pump of claim 19 further comprising a sensor that is in fluidic communication with the gas inlet of the vacuum pump.
  • 22. The radial turbomolecular vacuum pump of claim 19 further comprising an analytical instrument that is in fluidic communication with the gas inlet of the vacuum pump.
  • 23. The radial turbomolecular vacuum pump of claim 22 wherein the analytical instrument comprises a mass spectrometer.
  • 24. The radial turbomolecular vacuum pump of claim 19 wherein a side of the rotor comprises a molecular drag pump.
  • 25. The radial turbomolecular vacuum pump of claim 19 wherein the molecular drag pump comprises a flat spiral groove.
  • 26. The radial turbomolecular vacuum pump of claim 19 wherein the fore pump comprises a scroll pump.
  • 27. A method for pumping a gas with a turbomolecular vacuum pump, the method comprising:a) receiving the gas through a gas inlet; b) rotating a plurality blades that are substantially axially disposed and arranged in concentric rings relative to a first and second plurality of vanes arranged in concentric stator rings that are disposed between the concentric rings of the plurality of blades, wherein the relative motion of the plurality of blades and the first and second plurality of vanes causes gas to be pumped in a substantially radial direction from the concentric rings of blades through the concentric stator rings; and c) exhausting the gas through a gas outlet.
  • 28. The method of claim 27 further comprising compressing the gas.
  • 29. The method of claim 27 wherein the gas is pumped outwardly in a substantially radial direction.
  • 30. The method of claim 27 wherein the gas is pumped inwardly in a substantially radial direction.
  • 31. The method of claim 27 further comprising the step of rotating a second plurality of blades that are substantially axially disposed and arranged in concentric rings relative to a third and a fourth plurality of vanes arranged in concentric stator rings, wherein the relative motion of the second plurality of blades and the third and the fourth plurality of vanes causes gas to be pumped in a substantially radial direction from the concentric rings of blades through the concentric stator rings.
  • 32. A radial turbomolecular vacuum pump comprising:a) means for receiving a gas; b) means for rotating a plurality blades that are substantially axially disposed and arranged in concentric rings relative to a first and second plurality of vanes arranged in concentric stator rings that are disposed between the concentric rings of the plurality of blades, wherein the relative motion of the plurality of blades and the first and second plurality of vanes causes the gas to be pumped in a substantially radial direction from the concentric rings of blades through the concentric stator rings; and c) means for exhausting the gas through a gas outlet.
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