1. A method for addressing a glitch during an implantation of ions into a workpiece, the method comprising:
providing an ion beam;
determining an ion beam glitch duration threshold, wherein the ion beam glitch duration threshold is based, at least in part, on one or more of a number of translations of the workpiece through an ion beam, a velocity of the translation, and a size of the ion beam;
translating the workpiece through the ion beam along at least a slow scan path, therein implanting ions into the workpiece;
iteratively determining a current of the ion beam at a plurality of predetermined intervals during the translation of the workpiece;
setting a counter to zero when the determined current of the ion beam is greater than a predetermined value;
storing a position of the workpiece when the counter is zero and the determined current of the ion beam is less than the predetermined value, therein defining an onset of a glitch;
incrementing the counter for each iteration that the determined current of the ion beam is less than the predetermined value and the position of the workpiece is stored;
suppressing the ion beam if the counter exceeds the ion beam glitch duration threshold; and
repositioning the workpiece at the stored position, restarting the ion beam, and again translating the workpiece through the ion beam along at least the slow scan path, therein implanting a portion of the workpiece associated with the glitch.
2. The method of claim 1, further comprising recalculating the ion beam glitch duration threshold after suppressing the ion beam, wherein the recalculation is based, at least in part, on one fewer translations of the workpiece through the ion beam along the slow scan path.
3. The method of claim 2, further comprising halting the ion implantation when the ion beam glitch duration is less than the predetermined minimum.
4. The method of claim 1, wherein predetermined value of the current of the ion beam is approximately 10% of a normal operational ion implantation current.
5. The method of claim 1, wherein providing the ion beam comprises scanning a pencil beam along a fast scan path, wherein the fast scan path is generally perpendicular to the slow scan path.
6. The method of claim 1, wherein iteratively determining the current of the ion beam comprises measuring the current of the ion beam when the ion beam does not intersect the workpiece along a fast scan path.
7. The method of claim 5, wherein determining the current of the ion beam comprises measuring the current of the ion beam via a Faraday cup.
8. The method of claim 1, wherein determining the current of the ion beam comprises measuring one or more properties associated with a source of the ion beam.
9. A method for addressing an ion implantation anomaly, the method comprising:
providing a predetermined glitch duration threshold;
providing an ion beam;
translating a workpiece through the ion beam;
iteratively measuring a current of the ion beam concurrent with the translation;
storing a position of the workpiece when the measured current of the ion beam is less than a predetermined ion beam anomaly current, therein defining an onset of a glitch; and
halting the ion implantation and repairing the ion implantation associated with the glitch only when the measured current of the ion beam is lower than the predetermined ion beam anomaly current for a time greater than the predetermined glitch duration threshold.
10. The method of claim 9, further comprising repositioning the workpiece after the ion implantation is halted, wherein the workpiece is at the stored position when the repair of the ion implantation is started.
11. The method of claim 9, wherein translating the workpiece through the ion beam comprises reciprocating the workpiece along a fast scan path and translating the workpiece along a slow scan path, wherein the slow scan path is generally perpendicular to the fast scan path.
12. The method of claim 11, wherein iteratively measuring the current of the ion beam comprises measuring the current at an inflection position associated with a reversal of direction of the workpiece along the fast scan path.
13. The method of claim 9, wherein translating the workpiece through the ion beam comprises reciprocating the ion beam along a fast scan path and translating the workpiece along a slow scan path, wherein the slow scan path is generally perpendicular to the fast scan path.
14. The method of claim 13, wherein iteratively measuring the current of the ion beam comprises measuring the current at an inflection position associated with a reversal of direction of the ion beam along the fast scan path.
15. The method of claim 9, further comprising decreasing the predetermined glitch duration threshold by a predetermined amount each time the ion implantation is halted and repaired.
16. The method of claim 15, wherein the predetermined amount is associated with a time taken to translate the workpiece along a slow scan path during the ion implantation.
17. The method of claim 15, wherein the ion implantation is not repaired once the predetermined glitch duration threshold is less than a predetermined minimum.
18. The method of claim 9, wherein the predetermined ion beam anomaly current is approximately 10% of a normal operational ion implantation current.
19. The method of claim 9, wherein the predetermined glitch duration threshold is based, at least in part, on one or more of a number of translations of the workpiece along a slow scan path through the ion beam, a velocity of the translation along the slow scan path, and a size of the ion beam.
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 method for accessing a subterranean zone from a surface, comprising:
forming an entry well from a surface; and
forming two or more exterior drainage wells from the entry well to the subterranean zone, the exterior drainage wells each extending at least outward from the entry well for a first distance and then at least downward for a second distance, and at least two of the exterior drainage wells operable to drain fluid from the subterranean zone.
2. The method of claim 1, further comprising
forming a cavity in at least one of the exterior drainage wells, wherein the cavity intersects a portion of the subterranean zone and is operable to drain fluid from the subterranean zone.
3. The method of claim 1, wherein the exterior drainage wells intersect a plurality of subterranean zones.
4. The method of claim 1, wherein the subterranean zone comprises a coal seam.
5. The method of claim 1, further comprising
drilling a central drainage well extending downwardly from the entry well in a substantially vertical orientation to the subterranean zone, the central drainage well operable to drain the subterranean zone.
6. The method of claim 5, further comprising forming a cavity in the central drainage well, wherein the cavity intersects a portion of the subterranean zone and is operable to drain fluid from the subterranean zone.
7. The method of claim 1, further comprising forming a plurality of drainage systems each comprising an entry well and two or more associated exterior drainage wells, the drainage systems located in proximity to one another such that they nest adjacent one another.
8. The method of claim 1, further comprising:
positioning a pump inlet in one or more of the exterior drainage wells; and
pumping fluid produced from the subterranean zone from the pump inlet to the surface.
9. The method of claim 1 wherein the exterior drainage wells each extend at least outwardly and downwardly from the entry well for the first distance.
10. The method of claim 1 wherein extending at least outward from the entry well for a first distance comprises extending outward and downward from the entry well for a first distance.
11. A method for accessing a plurality of subterranean zones from a surface, comprising:
forming an entry well from the surface; and
forming two or more exterior drainage wells from the entry well through the plurality of subterranean zones, wherein at least one exterior drainage well is operable to drain fluid from at least two of the plurality of subterranean zones.
12. The method of claim 11, further comprising forming a cavity proximate an intersection of one or more of the exterior drainage wells and one or more of the subterranean zones.
13. The method of claim 11, further comprising drilling a central drainage well extending downwardly from the entry well in a substantially vertical orientation through the subterranean zones, the central drainage well operable to drain one or more of the subterranean zones.
14. The method of claim 13, wherein the central drainage well comprises a larger diameter than the exterior drainage wells.
15. The method of claim 13, further comprising forming a cavity in the central drainage well.
16. The method of claim 11, wherein the subterranean zone comprises a coal seam.
17. The method of claim 11, wherein at least a portion of one exterior drainage well extends downward.
18. The method of claim 11, wherein each exterior drainage well is operable to drain fluid from the plurality of subterranean zones.
19. The method of claim 11, further comprising forming a plurality of drainage systems each comprising an entry well and two or more associated exterior drainage wells, the drainage systems located in proximity to one another such that they nest adjacent one another.
20. The method of claim 11, further comprising:
positioning a pump inlet in one or more of the exterior drainage wells; and
pumping fluid produced from the plurality of subterranean zones from the pump inlet to the surface.