A method for removing microscopic contaminant particulates by high pressure liquid nitrogen jet cleaning from the inner surface of a superconducting radio frequency cavity or a string of multiple cavities and transporting the removed particulates out of the inner space enclosed by the cleaned surfaces. The cleaning method of the invention suppresses field emission, resulting in an increase of the usable accelerating gradient of the cavities and a reduction of the activated radioactivity in accelerator components around cavities.

An input coupler for an accelerating cavity includes a cylindrical external conductor; a cylindrical internal conductor arranged coaxially with the external conductor, inside of which a heating medium circulates; a plate provided between the inner surface of the external conductor and the outer surface of the internal conductor; a cooling part for cooling the plate from the external conductor side to the freezing point of water or lower; and a heat insulating part provided on the part at which the internal conductor and the plate are connected, the heat insulating part having lower thermal conductivity than that of the internal conductor. The plate is connected to the internal conductor via the heat insulating part.

An input coupler for an accelerating cavity includes a cylindrical external conductor; a cylindrical internal conductor arranged coaxially with the external conductor, inside of which a heating medium circulates; a plate provided between the inner surface of the external conductor and the outer surface of the internal conductor; a cooling part for cooling the plate from the external conductor side to the freezing point of water or lower; and a heat insulating part provided on the part at which the internal conductor and the plate are connected, the heat insulating part having lower thermal conductivity than that of the internal conductor. The plate is connected to the internal conductor via the heat insulating part.

An accelerator comprising at least one accelerator cavity, an electron gun, at least one cavity cooler configured to at least partially encircle the accelerator cavity, a cooling connector, an intermediate conduction layer formed between the at least one cavity cooler and the at least one accelerator cavity configured to facilitate thermal conductivity between the cavity cooler and the accelerator cavity, a mechanical support connected to the accelerator cavity via at least one endplate and configured for stabilizing the accelerator cavity, and a refrigeration source for providing refrigerant via the cooling connector to the at least one cavity cooler.

A system and method for treating a cavity comprises preparing a superconducting radio frequency (SRF) cavity for removal of a dielectric layer from on an inner surface of the SRF cavity, subjecting the SRF cavity to a heat treatment in order to remove the dielectric layer from the inner surface of the SRF cavity, and preventing the development of a new dielectric layer on the inner surface of the SRF cavity by preventing an interaction between the inner surface of the SRF cavity and atmospheric gasses.

A system and method for treating a cavity comprises preparing a superconducting radio frequency (SRF) cavity for removal of a dielectric layer from on an inner surface of the SRF cavity, subjecting the SRF cavity to a heat treatment in order to remove the dielectric layer from the inner surface of the SRF cavity, and preventing the development of a new dielectric layer on the inner surface of the SRF cavity by preventing an interaction between the inner surface of the SRF cavity and atmospheric gasses.

An electric power converter includes a semiconductor module, a cooler, and a pair of direct current bus bars. The direct current bus bars are connected to the semiconductor. The direct current bus bars serve as current paths between the direct current power supply and the switching element. The cooler is made of metal, and is electrically connected to ground. A proximal bypass capacitor is formed close to the switching element by a heat radiating plate integrated with the semiconductor module, the cooler, and an insulating layer interposed between them. The electric power converter further includes a pair of distal bypass capacitors, each of which has a larger capacitance than the proximal bypass capacitor has, and has a current path to the switching element of which a length is longer than a current path to the switching element from the proximal bypass capacitor.

An accelerator comprising at least one accelerator cavity, an electron gun, at least one cavity cooler configured to at least partially encircle the accelerator cavity, a cooling connector, an intermediate conduction layer formed between the at least one cavity cooler and the at least one accelerator cavity configured to facilitate thermal conductivity between the cavity cooler and the accelerator cavity, a mechanical support connected to the accelerator cavity via at least one endplate and configured for stabilizing the accelerator cavity, and a refrigeration source for providing refrigerant via the cooling connector to the at least one cavity cooler.

Disclosed below are representative embodiments of methods, apparatus, and systems for generating electrons. For example, certain embodiments comprise a charge gating diamond QED based electron source, which can be suspended within the RF cavity of an electron injection system in a superconducting radiofrequency (SRF) electron accelerator. Embodiments of the disclosed technology are capable of producing low temperature (cold) electron beams, where temperature refers to the transverse energy in the extracted electron beam (or beam emittance). Embodiments of the disclosed technology can also exhibit enhanced charge replenishment capabilities by virtue of the material selected to suspend the electron source within the RF cavity of the electron injection system.

Disclosed below are representative embodiments of methods, apparatus, and systems for generating electrons. For example, certain embodiments comprise a charge gating diamond QED based electron source, which can be suspended within the RF cavity of an electron injection system in a superconducting radiofrequency (SRF) electron accelerator. Embodiments of the disclosed technology are capable of producing low temperature (cold) electron beams, where temperature refers to the transverse energy in the extracted electron beam (or beam emittance). Embodiments of the disclosed technology can also exhibit enhanced charge replenishment capabilities by virtue of the material selected to suspend the electron source within the RF cavity of the electron injection system.