Radio frequency field immersed ultra-low temperature electron source

An electron injection system for a superconducting radiofrequency (SRF) accelerator system, comprising:

• a liquid-cooled vessel defining a radio frequency (RF) cavity in which an electron source is located;
• an electron source located within the RF cavity, but not in direct contact with any surface of the RF cavity;
• and
• one or more light guides configured to transmit photons from a photon source external the RF cavity to a back plane of the electron source, thus causing electron emission from the electron source.

An electron injection system for a superconducting radiofrequency (SRF) accelerator system, comprising:

• a liquid-cooled vessel defining a radio frequency (RF) cavity in which an electron source is located;
• and
• an electron source located within the RF cavity, but not in direct contact with any surface of the RF cavity,
• wherein the electron source comprises a diamond structure or a diamond QED based electron source.

A method, comprising:

• suspending an electron source within an injector cavity of a superconducting radiofrequency (SRF) accelerator system such that the electron source is located within an RF cavity, but not in direct contact with any surface of the RF cavity;
• and
• selectively transmitting photons to a back plane of the electron source at times synchronized with the periodic RF field generated in the RF cavity, the photons being generated from a light source external to the RF cavity,
• wherein the selectively transmitting photons is performed by transmitting photons toward the back plane of the electron source through one or more light guides that have respective transmission ends that are located at the back wall of the RF cavity or extend into the RF cavity.

A system, comprising:

• a superconducting radiofrequency (SRF) accelerator system, comprising:
• a liquid-cooled vessel defining a radio frequency (RF) cavity in which an electron source is located;
• and
• a photon-activated electron source located within the RF cavity, the photon-activated electron source being suspended in an interior of the RF cavity distal from an end wall of the RF cavity,
• wherein the photon-activated electron source is suspended within the RF cavity by one or more support structures comprising one or more filaments having variable semiconductivity.