Intense nanosecond duration source of 10–250 keV x rays suitable for imaging projectile-induced cavitation in human cadaver tissue

Abstract

The design, fabrication, and performance of a repetitive nanosecond x-ray source having a pumped field-emission x-ray tube are described. A compact Marx generator, 61 cm in length and storing 12 J energy, directly drives the field-emission tube with voltage pulses >380kV and with <4ns rise time from an equivalent generator impedance of 52Ω. The x-ray dose is 520 μSv at a distance of 30.5 cm. A numerical simulation model is used in which the x-ray tube’s cathode width and anode-cathode gap spacing are permitted to change with time, while electron flow between the cathode and anode is space charge limited and nonrelativistic. The x-ray tube model is coupled to an equivalent circuit representation of the Marx generator that includes the capacitance variation with charging voltage of the BaTiO3 capacitors. The capabilities of the x-ray source for flash radiography have been demonstrated by the study of the evolution of cavitation in human cadaver legs induced by high-velocity projectiles.

A broadband laser plasma x-ray source for application in ultrafast chemical structure dynamics

“…37,38 At the present time there are four independent handles on this question. The first is the streak camera measurements, which merely permit the statement that the observed x-ray pulse duration is less than or at most comparable to that instrument's temporal resolution function.…”

Characterization of multiphase flows integrating X-ray imaging and virtual reality

“…A special type of tube source is the flash X-ray source. The primary difference between a standard tube source and a flash X-ray tube is the flash sources typically run at much high power, but for very short periods (on the order of nanoseconds) (Boyer et al, 2005). In any X-ray tube, a large portion of the energy of the electrons is converted to heat in the anode.…”

“…While these systems allowed scientists to view flows in real time, they could not record data for later analysis or slow down events that were too fast to be observed by the human eye. The use of X-ray sensitive film allowed for the direct recording of data, but due to the relative insensitivity of X-ray film, this process required long exposures or high X-ray intensity, and time consuming development processes (Boyer et al, 2005;Chotas et al, 1999). Therefore, it was not until the development of digital X-ray detection systems that time-sequenced radiography became the powerful tool for fluid flow research it is today (Heindel, 2011).…”

“…Most direct X-ray detectors are only capable of 30 frames per second (FPS), and indirect detectors are limited by the decay rate of the phosphor screen (Gruner et al, 2002;Seibert, 2006). Flash X-ray systems use high-power, short duration Xray pulses to take images at higher speeds, but are generally limited to generating a small number of frames because of energy storage bank recharge times and anode deterioration (Boyer et al, 2005;Heindel, 2011). For example, Romero and Smith (1965) used flash X-ray radiography to examine fluidized beds, but were limited to two radiographs, at different spatial locations, per experiment.…”

“…Heindel andMonefeldt (1997, 1998) later used flash X-ray to examine pulp suspensions in bubble columns, and although they achieved 30 nanosecond exposure time, they were limited to single X-ray frames. Finally, Grady and Kipp (1994) and Boyer et al (2005) used flash radiography to image projectiles, with Boyer et al achieving up to 50 consecutive frames before significant anode deterioration.…”