1. A damper, comprising:
a cylinder containing a magnetorheological fluid;
a piston slidably mounted for reciprocal movement in the cylinder, wherein the piston includes a core and a flux ring positioned about the core, the core and flux ring defining an annular, axially directed flow gap therebetween; and
at least one non-magnetic portion positioned along the flow gap in at least one of the flux ring and the core, wherein the non-magnetic portion includes at least one groove formed therein and positioned along at least a portion of the flow gap.
2. The damper of claim 1, further comprising:
a coil disposed in the piston core, wherein the at least one groove is an interrupted groove formed adjacent the coil.
3. The damper of claim 2 wherein the at least one groove is an interrupted groove formed in the core above and below the coil.
4. The damper of claim 3 wherein the at least one groove is formed in the core pole pieces.
5. The damper of claim 1 wherein the at least one groove is a plurality of axial grooves arranged about one or both of the core and the flux ring.
6. The damper of claim 5 wherein the plurality of grooves are formed on an outer surface of the core.
7. The damper of claim 5 wherein the plurality of grooves are formed on an inner surface of the flux ring.
8. The damper of claim 1 wherein the non-magnetic material is a polymeric material.
9. The damper of claim 1 wherein the non-magnetic portion is disposed in at least one axial slot formed in the flux ring.
10. The damper of claim 1 wherein the non-magnetic portion is disposed in at least one axial slot formed in the core.
11. The damper of claim 1 wherein the at least one groove extends along an entire length of the flux ring and in communication with the flow gap along an entire length of the groove.
12. A method for providing a smooth transition between low and high velocity damping forces in a fluid damper for a vehicle suspension comprising:
generating a predetermined flux level through a gap formed between a first and second chamber of the damper, wherein the gap comprises an annular, axially directed passage within a piston assembly of the damper; and
generating a decreased flux level through at least one groove, an entire length of the groove formed in communication with the gap, wherein the groove is formed in a non-magnetic portion of the piston and axially directed along at least a portion of a length of one of an inner wall and an outer wall defining the annular, axially directed passage.
13. A damper for providing a smooth transition between low and high velocity damping forces in a fluid damper for a vehicle suspension comprising:
means for generating a predetermined flux level through a gap formed between a first and second chamber of the damper, wherein the gap comprises an annular, axially directed passage within a piston assembly of the damper; and
means for generating a decreased flux level through at least one groove, an entire length of the groove formed in communication with the gap, wherein the groove is formed in a non-magnetic portion of the piston and axially directed along at least a portion of a length of one of an inner wall and an outer wall defining the annular, axially directed passage.
14. A damper, comprising:
a cylinder containing a magnetorheological fluid; and a piston assembly slidably mounted for reciprocal movement in the cylinder to form a first chamber positioned on one side of the piston assembly and a second chamber positioned on an opposite side of the piston assembly, wherein the piston assembly includes a fluid flow passage therethrough defining a flow gap permitting limited fluid flow between the first chamber and the second chamber, wherein the flow gap includes a groove adjacent and open to the flow gap along at least a portion of the flow gap in the direction of fluid flow, the groove being formed in a portion of the piston assembly comprised of a non-magnetic material, the groove being axially directed along one of an inner wall and an outer wall defining the flow gap, the piston assembly further including a magnet assembly establishing a magnetic flux circuit through the flow gap and through the groove in series with a region of the flow gap adjacent the groove, the magnetic flux being established through the flow gap and groove transversely to the direction of fluid flow therethrough to cause magnetorheological fluid flowing through the flow gap and the groove to experience a magnetorheological effect affecting the flow of the magnetorheological fluid therethrough, whereby the groove and non-magnetic portion of the piston causes the magnetic flux density therethrough to be smoothly reduced from that in the remainder of the flow gap.
15. The damper of claim 14, wherein the magnetic flux circuit comprises magnetic poles defining the flow gap, the flow gap and groove in series providing a greater gap width thereacross between the magnetic poles than the flow gap alone.
16. The damper of claim 14, wherein the groove is formed by a curvilinear surface.
17. The damper of claim 14, wherein the groove has the shape of a polygon.
18. The damper of claim 14, wherein the groove is formed by a triangular surface.
19. The damper of claim 14, wherein the annular, axially directed passage comprises a plurality of grooves formed therealong.
20. The damper of claim 14, wherein the groove is lined with a non-magnetic material adapted to lower the flux density in the groove.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A plasma processing apparatus comprising:
a processing chamber disposed inside a vacuum vessel;
a first high-frequency power supply outputting a first high-frequency power for supplying an electric field to generate a plasma for use in processing a sample to be processed inside the processing chamber;
a sample stage disposed inside the processing chamber with the sample placed on an upper surface thereof;
a second high-frequency power supply intermittently outputting a second high-frequency power for generating a bias potential to an electrode disposed inside the sample stage and capable of variably adjusting the output time, and
a function to adjust operation of the plasma processing apparatus using a result of detection of a temporal change in waveform of current or voltage in a transient state of the second high-frequency power in synchronism with a start of the intermittent output of the second high-frequency power.
2. A plasma processing apparatus comprising:
a processing chamber disposed inside a vacuum vessel;
a first high-frequency power supply outputting a first high-frequency power for supplying an electric field to generate plasma for use in processing a sample to be processed inside the processing chamber;
a sample stage disposed inside the processing chamber with the sample placed on an upper surface thereof;
a second high-frequency power supply outputting a second high-frequency power for generating a bias potential to an electrode disposed inside the sample stage and capable of variably adjusting ON time and OFF time of the output or a ratio thereof, and
a function to adjust operation of the plasma processing apparatus using a result of detection of a temporal change in waveform of current or voltage in a transient state of the second high-frequency power in synchronism with a start of ON period of the second high-frequency power.
3. The plasma processing apparatus according to claim 1, wherein
the first high-frequency power supply outputs the first high-frequency power in synchronism with an output of the second high-frequency power.
4. The plasma processing apparatus according to claim 1, wherein
the second high-frequency power is output in synchronism with a cyclical signal serving as a reference, and a temporal change in waveform of current or voltage in a transient state of the second high-frequency power is detected in synchronism with the cyclical signal.
5. The plasma processing apparatus according to claim 4, wherein
the second high-frequency power supply outputs the second high-frequency power so that a waveform of the second high-frequency power is synchronized with the cyclical signal, and a temporal change in the waveform is detected by comparing a plurality of waveforms of current or voltage with each other in a predetermined time length in a transient state of the second high-frequency power.
6. The plasma processing apparatus according to claim 1, wherein
a temporal change in the waveform is detected by comparing a plurality of waveforms of current or voltage with each other, whose phase is aligned to other phases, in a predetermined time length in a transient state of the second high-frequency power.
7. The plasma processing apparatus according to claim 1, wherein
stop of the plasma processing apparatus or change of the processing condition is conducted using a result of detection of the temporal change in waveform of current or voltage in the transient state of the second high-frequency power.
8. The plasma processing apparatus according to claim 1, wherein
the waveform of the second high-frequency power is detected at every predetermined time interval in the transient state.