The present invention provides a process and structure of microfabricated air bridges for planar microwave resonator circuits. In an embodiment, the invention includes depositing a superconducting film on a surface of a base material, where the superconducting film is formed with a compressive stress, where the compressive stress is higher than a critical buckling stress of a defined structure, etching an exposed area of the superconducting film, thereby creating the at least one bridge, etching the base material, thereby forming a gap between the at least one bridge and the base material, depositing the at least one metal line on at least part of the superconducting film and at least part of the base material, where the at least one metal line runs under the bridge.

The present invention provides a process and structure of microfabricated air bridges for planar microwave resonator circuits. In an embodiment, the invention includes depositing a superconducting film on a surface of a base material, where the superconducting film is formed with a compressive stress, where the compressive stress is higher than a critical buckling stress of a defined structure, etching an exposed area of the superconducting film, thereby creating the at least one bridge, etching the base material, thereby forming a gap between the at least one bridge and the base material, depositing the at least one metal line on at least part of the superconducting film and at least part of the base material, where the at least one metal line runs under the bridge.

A superconducting radio frequency (SRF) cell includes a body defining a hollow cavity having a first iris at a first end of the body, a second iris at a second end of the body, an axis that extends between the first and second irises and an equator around the axis between the first and second irises. The body includes a first weld seam around the axis at a location on the body spaced from the equator. A method for producing the SRF cavity includes: (a) providing a first-partial cell including a first cell welding edge; (b) providing a second-partial cell including a second cell welding edge; (c) positioning the first- and second-partial cells with the first and second cell welding edges facing toward each other; and (d) welding the first- and second-partial cells together at a position other than the equator of the body.

A superconducting radio frequency (SRF) cell includes a body defining a hollow cavity having a first iris at a first end of the body, a second iris at a second end of the body, an axis that extends between the first and second irises and an equator around the axis between the first and second irises. The body includes a first weld seam around the axis at a location on the body spaced from the equator. A method for producing the SRF cavity includes: (a) providing a first-partial cell including a first cell welding edge; (b) providing a second-partial cell including a second cell welding edge; (c) positioning the first- and second-partial cells with the first and second cell welding edges facing toward each other; and (d) welding the first- and second-partial cells together at a position other than the equator of the body.

A superconducting radio frequency cell includes a body defining a hollow cavity having a first iris and second iris at opposite ends of the body, an axis that extends between the first and second irises, and an equator around the axis between the first and second irises. The body includes at least a first weld seam around the axis at a location on the body spaced from the equator. Each weld seam extends through the body and has opposite sides terminating proximate an interior and an exterior of the body, and each weld seam includes a first, conduction weld formed on one side of the weld seam and a second weld formed on the opposite side of the weld seam. The second weld can be a conduction weld, a keyhole weld, or a transition weld.

A superconducting radio frequency cell includes a body defining a hollow cavity having a first iris and second iris at opposite ends of the body, an axis that extends between the first and second irises, and an equator around the axis between the first and second irises. The body includes at least a first weld seam around the axis at a location on the body spaced from the equator. Each weld seam extends through the body and has opposite sides terminating proximate an interior and an exterior of the body, and each weld seam includes a first, conduction weld formed on one side of the weld seam and a second weld formed on the opposite side of the weld seam. The second weld can be a conduction weld, a keyhole weld, or a transition weld.

A high performance accelerator structure and method of production. The method includes precision machining the inner surfaces of a pair of half-cells that are maintained in an inert atmosphere and at a temperature of 100 K or less. The method includes removing thin layers of the inner surfaces of the half-cells after which the roughness of the inner surfaces in measured with a profilimeter. Additional thin layers are removed until the inner surfaces of the half-cell measure less than 2 nm root mean square (RMS) roughness over a 1 mm.sup.2 area on the profilimeter. The two half-cells are welded together in an inert atmosphere to form an SRF cavity. The resultant SRF cavity includes a high accelerating gradient (E.sub.acc) and a high quality factor (Q.sub.0).

A high performance accelerator structure and method of production. The method includes precision machining the inner surfaces of a pair of half-cells that are maintained in an inert atmosphere and at a temperature of 100 K or less. The method includes removing thin layers of the inner surfaces of the half-cells after which the roughness of the inner surfaces in measured with a profilimeter. Additional thin layers are removed until the inner surfaces of the half-cell measure less than 2 nm root mean square (RMS) roughness over a 1 mm.sup.2 area on the profilimeter. The two half-cells are welded together in an inert atmosphere to form an SRF cavity. The resultant SRF cavity includes a high accelerating gradient (E.sub.acc) and a high quality factor (Q.sub.0).

Methods and systems for non-invasively tuning dressed multicell cavities. A multicell cavity can be plastically deformed as result of introducing a customized balloon to a cavity and then pressurizing the balloon to a targeted cell while applying a global force on the cavity flanges. The pressurized balloons localize the plastic deformation to the targeted cells using prescribed values of both global force and balloon pressure. Such an approach allows for the tuning of dressed cavities without removal of the helium vessel.

Methods and systems for non-invasively tuning dressed multicell cavities. A multicell cavity can be plastically deformed as result of introducing a customized balloon to a cavity and then pressurizing the balloon to a targeted cell while applying a global force on the cavity flanges. The pressurized balloons localize the plastic deformation to the targeted cells using prescribed values of both global force and balloon pressure. Such an approach allows for the tuning of dressed cavities without removal of the helium vessel.