Active vibration reduction

Abstract

In a system that includes an active magnetic bearing, a magnetic bearing may induce vibration in anti-phase with an unwanted vibration so that the total vibration in the system is reduced. A magnetic bearing in one pump may be used to cancel vibration from another pump in this way.

1 . A method of reducing vibration in a pumped system, comprising: 
 measuring a first vibration; and    producing a second vibration in a pump, the second vibration being in anti-phase with the first vibration.    
     
     
         2 . The method of  claim 1  wherein, the pump is a turbomolecular pump.  
     
     
         3 . The method of  claim 1  wherein, the first vibration is measured at a process chamber.  
     
     
         4 . The method of  claim 1  wherein, the first vibration is generated by a second pump that is connected to the first pump.  
     
     
         5 . The method of  claim 1  wherein, the second vibration is produced by a magnetic bearing in the pump.  
     
     
         6 . The method of  claim 1  further comprising sending a signal to the pump in response to the first vibration.  
     
     
         7 . A method of active vibration reduction in a pumped system, comprising: 
 measuring a first vibration;    generating a control signal in response to the first vibration; and    sending the control signal to a magnetic bearing in a pump to induce a second vibration in the pump, the second vibration being in opposition to the first vibration such that the sum of the first vibration and the second vibration is less than the first vibration.    
     
     
         8 . The method of  claim 7  further comprising creating a reduced pressure in a chamber using the pump.  
     
     
         9 . The method of  claim 8  wherein the first vibration is measured at the chamber.  
     
     
         10 . The method of  claim 7  wherein, the first vibration is measured at an inlet of the pump.  
     
     
         11 . A pumped system, comprising: 
 a pump that comprises a magnetic bearing;    a vibration detector that generates a detection signal in response to a first vibration; and    a control circuit that sends a control signal to the magnetic bearing in response to the detection signal, the control signal inducing a second vibration in the pump.    
     
     
         12 . The pumped system of  claim 11  wherein, the second vibration is in anti-phase with the first vibration.  
     
     
         13 . The pumped system of  claim 11  further comprising a flange that attaches the pump to a process chamber.  
     
     
         14 . The pumped system of  claim 13  wherein the vibration detector is attached to the flange.  
     
     
         15 . A pumped system, comprising: 
 a first pump that produces a first vibration;    a second pump that comprises a magnetic bearing;    a vibration detector that generates a detection signal in response to the first vibration; and    a control circuit that sends a control signal to the magnetic bearing in response to the detection signal, the control signal inducing a second vibration in the second pump.    
     
     
         16 . The pumped system of  claim 15  wherein the first pump is a dry pump.  
     
     
         17 . The pumped system of claim of  claim 15  wherein the second pump is a turbomolecular pump.  
     
     
         18 . The pumped system of  claim 15  further comprising an attaching element configured to allow the pumping system to be attached to a host.  
     
     
         19 . The pumped system of  claim 18  wherein the vibration detector is mounted on the attaching element.  
     
     
         20 . The pumped system of  claim 15  wherein, the second pump is configured to remove gas from a chamber and the first pump is attached to the second pump and is configured to remove gas from the second pump.