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[en] We developed a solid-state high voltage pulse generator for a 50 kV thermionic electron gun of the next-generation SR source facility. The generator should be stable, compact, and reliable. To realize the generator, we designed Marx generator using ultra-high voltage Silicon Carbide (SiC) MOSFETs. The MOSFET has characteristics, such as a high withstanding voltage of 13 kV and a fast turn-on transient time of 100 ns. At the operation test, the generator outputs a 50 kV, 1 μs pulse to a 25 kΩ load resistor at a 30 Hz repetition rate. (author)
[en] The high-voltage pulse modulator based on the modern semiconductor elements is described. The modulator is intended for use in the power supply system of LINAC helium ions injector and has the ability to smoothly adjust the amplitude (110…150 kV) and the pulse duration (0.5…1 ms). The use of a pulse-to-peak stabilization scheme, made on the basis of a parametric stabilizer with parallel switching of the load, made it possible to increase the accelerated current at the accelerator output by 2 times.
[en] In this work, the radiofrequency inductive rings are placed on a pulsed plasma jet plume to improve its efficiency and capability. The optical emission spectroscopy method is used to examine the physical and technical features of the improved pulsed plasma jet. The influences of applied impulse voltage and frequency on the pulsed plasma jet along with the inductive rings diameter and its turns and applied RF voltage amplitude on its performance are studied. It is seen that, at the higher applied voltages and frequencies on the pulsed plasma jet, while the plasma density is increased, the plasma electron excitation and rotational temperatures will decrease. Furthermore, the inductive RF voltage application on the rings enhances the ionization rate and plasma density of the jet, and consequently, the excitation and rotational temperatures of plasma electrons are reduced. Increasing of the applied inductive RF voltage amplitudes on the ring will result in the higher electrons density and reduction in the excitation and rotational temperatures. It is shown that, at the higher inductive ring diameters and its turns, the excitation temperature of plasma electrons is reduced. (author)
[en] We have developed a prototype of bipolar pulse accelerator (BPA), which can generate an intense pulsed ion beam with higher purity than the conventional ion diode. The BPA is operated with the bipolar pulse voltage and is a two-stage electrostatic accelerator. A coaxial gas puff plasma gun was used as an ion source, which was installed inside the grounded anode. We found that the ion beam was successfully accelerated in the 1st and 2nd gaps by applying the bipolar pulsed voltage to the drift tube. However, the evaluation of the ion energy via time of flight is not enough to demonstrate the principle of the BPA. Therefore, in order to evaluate the characteristics of the accelerated ion beam, we used a solid track detector (CR-39) with multi-step etching technique. In this study, we evaluated the ion energy by measuring ion range in CR-39. The energy of the nitrogen ion was estimated to be 94±42 keV. (author)
PurposeTo evaluate the efficacy and safety of irreversible electroporation (IRE) in the treatment of unresectable hepatocellular carcinoma (HCC).
Materials and MethodsA retrospective study was conducted from September 2014 to June 2017. A total of 21 HCCs in 21 patients with cirrhosis were treated with IRE. There were eight subcapsular or exophytic, ten perivascular and three peribiliary tumors. The median tumor size was 26 mm (range 14–40 mm). The technical success of the procedure was recorded. Median follow-up, median time to local recurrence, median local tumor progression-free survival (PFS) and complications were recorded.
ResultsTechnical success was achieved in all the patients. The median follow-up was 10 months (range 2–30 months). The median time to local recurrence and local tumor PFS were 4 months (range 3–4 months) and 7 months (range 3–30 months), respectively. The tumor-related factor that was significantly associated with local PFS was the size. Maximum tumor diameter < 25 mm was significantly associated with local tumor PFS (p = 0.045). Other parameters including tumor location, segmental portal vein thrombosis, baseline alpha-fetoprotein level and underlying etiology did not affect local tumor PFS. Complications were noted in nine patients and were classified as grades 1 and 2. No procedure-related mortality was encountered.
ConclusionIRE is an effective treatment for ablation of small HCCs. Larger prospective studies with strict selection criteria will establish the safety and efficacy of IRE in the treatment of unresectable HCC in patients who cannot undergo thermal ablation.