The present disclosure provides a cathode emission device. The cathode emission device may comprise a cathode assembly, including: a first filament, a second filament, and a grid electrode. The grid electrode may be operably connected to the first filament and surrounding the first filament and the second filament. The cathode assembly may be configured to be operably connected to a high-voltage generator and switchable between a first connection configuration and a second connection configuration.

A power supply circuit and a field emission electron source are provided. The power supply circuit includes: field effect transistors S.sub.i coupled in series via drains and sources in sequence, 1≤i≤n, i and n are natural numbers, n≥2, and a source of S.sub.1 is coupled to a negative electrode of a voltage source, and a drain of S.sub.n is used as an output terminal of the power supply circuit to couple to a load; a first group of diodes D.sub.1i coupled in series; a first group of resistors R.sub.1j, 2≤j≤n, and i and j are natural numbers; and a voltage control module configured to adjust an output voltage of the voltage source to cause a current passing through the load to be constant; the field effect transistors S.sub.i, 1≤i≤n, operate in a resistive region.

At least one example embodiment provides an electron emitter apparatus having a first ring of field-effect emitter needles, the field-effect emitter needles of the first ring forming a first emitter surface on an inner side of the first ring; and a second ring of field-effect emitter needles, the field-effect emitter needles of the second ring forming a second emitter surface on an inner side of the second ring, wherein the first ring and the second ring are arranged in such that the first emitter surface and the second emitter surface form a substantially contiguous three-dimensional overall emitter surface, the substantially contiguous three-dimensional overall emitter surface defining a hollow channel along a longitudinal axis of the electron emitter apparatus.

Presented systems and methods facilitate efficient and effective monitoring of particle beams. In some embodiments, a radiation gun system comprises: a particle beam gun that generates a particle beam, and a gun control component that controls the gun particle beam generation characteristics, including particle beam fidelity characteristics. The particle beam characteristics can be compatible with FLASH radiation therapy. Resolution control of the particle beam generation can enable dose delivery at an intra-pulse level and micro-bunch level. The micro-bunch can include individual bunches per each 3 GHz RF cycle within the 5 to 15 μsec pulse-width. The FLASH radiation therapy dose delivery can have a bunch level resolution of approximately 4.4×10{circumflex over ( )}-6 cGy/bunch.

A C-arm X-ray apparatus includes an x-ray emitter (5) and an X-ray detector (4) which are maintained on a C-arm (2) mounted on a reference plane. The x-ray emitter (5) has nanorods as electron emitters and has an elongated structure which is at least partially aligned along a surface normal of the reference plane.

A power supply circuit and a field emission electron source are provided. The power supply circuit includes: field effect transistors S.sub.i coupled in series via drains and sources in sequence, wherein 1≤i≤n, n≥2, and wherein a source of S.sub.1 is coupled to a negative electrode of a voltage source, and a drain of S.sub.n is used as an output terminal of the power supply circuit to couple to a load; a first group of diodes D.sub.1i coupled in series; a first group of resistors R.sub.1j, 2≤j≤n; and a current feedback module configured to adjust an internal resistance of the field effect transistors S.sub.i, coupled in series in sequence, so as to cause a current passing through the load to be constant; wherein the field effect transistors S.sub.i, 1≤i≤n, operate in a constant current region.

Some example embodiments provide an x-ray tube for a stereoscopic imaging having an evacuated x-ray tube housing; an electron emitter apparatus in the x-ray tube housing, the electron emitter apparatus including a first field effect emitter with a first emitter surface and a second field effect emitter with a second emitter surface, at least one of the first emitter surface or the second emitter surface being segmented such that a portion of the at least one of the first emitter surface or the second emitter surface can be set relative to the respective overall emitter surface by selectively switching emitter segments of the at least one of the first emitter surface or the second emitter surface; an anode unit in the x-ray tube housing, the anode unit configured to generate x-ray radiation for the stereoscopic imaging as a function of electrons striking two focal points; and a control unit.

An emitter support structure for a field emission device, the emitter support structure includes: a support portion disposed to be moved in a direction of both ends of a vacuum chamber of the field emission device, and configured to support an emitter of the field emission device; a protruding portion formed at one end portion of the support portion which confronts a target of the field emission device, and to which the emitter is inserted and mounted; a slit formed in a circumference wall portion of the protruding portion in a height direction of the circumference wall portion; and a redundant brazing material groove formed in an outside of the protruding portion along the circumference wall portion.

An emitter support structure for a field emission device, the emitter support structure includes: a support portion disposed to be moved in a direction of both ends of a vacuum chamber of the field emission device, and configured to support an emitter of the field emission device; a protruding portion formed at one end portion of the support portion which confronts a target of the field emission device, and to which the emitter is inserted and mounted; a slit formed in a circumference wall portion of the protruding portion in a height direction of the circumference wall portion; and a redundant brazing material groove formed in an outside of the protruding portion along the circumference wall portion.

Presented systems and methods facilitate efficient and effective monitoring of particle beams. In some embodiments, a radiation gun system comprises: a particle beam gun that generates a particle beam, and a gun control component that controls the gun particle beam generation characteristics, including particle beam fidelity characteristics. The particle beam characteristics can be compatible with FLASH radiation therapy. Resolution control of the particle beam generation can enable dose delivery at an intra-pulse level and micro-bunch level. The micro-bunch can include individual bunches per each 3 GHz RF cycle within the 5 to 15 μsec pulse-width. The FLASH radiation therapy dose delivery can have a bunch level resolution of approximately 4.4×10{circumflex over ( )}−6cGy/bunch.