RESUMEN
Background: Geastrum is the largest genus of Geastraceae and is widely distributed all over the world. Four specimens which belong to Geastrum were collected during our scientific expedition to Cangshan Mountain, Yunnan, China. Based on morphological characteristics and phylogenetic analysis, a new species was introduced. New information: Geastrumsuae is characterised by its large basidiomata (height 35-70 mm, diameter 18-37 mm) with long stipe (height 10-45 mm), smooth pink exoperidium and sessile globose endoperidial body. Phylogenetic analysis has been carried out, based on the internal transcribed spacer (ITS) and large subunit ribosomal ribonucleic acid (nrLSU) sequence data. The illustration and description for the new taxa are provided.
RESUMEN
In this paper, the development of a five-stage solid-state linear transformer driver (LTD) is described. Each stage consists of eight compact pulse generating modules and a magnetic core. The pulse generating modules contain a multilayer-ceramic-capacitor-based pulse-forming network (PFN) and an insulated-gate bipolar transistor (IGBT) switch array, as well as magnetic switches, which are used to speed up the pulse front. To prevent damage from the reverse voltage to the IGBT switch, a reverse voltage absorption circuit was added to the PFN. For this study, a larger cross-sectional core with improved output characteristics was adopted. The developed five-stage LTD has the advantages of long life, low jitter, fast rising edge, and so on. The device can provide a 35 kV, 119 ns, 4.3 kA square pulse train with a maximum frequency of 50 Hz. On this basis, a 50-stage LTD of output 500 kV, which would serve as a high-power microwave driver source, is under development.
RESUMEN
A solid-state pulse-forming network (PFN) module was designed using multilayer ceramic capacitors (MLCCs). In addition, an all-solid-state pulse generator was fabricated with a Blumlein line that consisted of two PFN single lines and an insulated gate bipolar transistor (IGBT) switch array. This generator was integrated on printed circuit boards (PCBs). The stage capacitors of the PFN were composed of MLCCs connected in series and parallel. To obtain a compact structure, folded, copper-clad wires were used as interstage inductors. The copper-clad wires were structurally optimized to reduce coupling between adjacent interstage inductors. A relatively fast rising waveform edge was obtained using an IGBT gate-boosting circuit and magnetic switch technology. A square-wave pulse with a rise time of 27 ns, a voltage of 5 kV, a width of 120 ns, a maximum repetition rate of 100 Hz, and an evaluated lifetime of 109 pulses was obtained on a load of 6.6 Ω. With its compact size, fast rise time, and long lifetime, the fabricated pulse generator can be used as a component in linear transformer drivers or Marx generators.
RESUMEN
A compact multiterawatt laser system based on optical parametric chirped pulse amplification is demonstrated. Chirped pulses are amplified from 20 pJ to 900 mJ by two lithium triborate optical parametric preamplifiers and a final KDP optical parametric power amplifier with a pump energy of 5 J at 532 nm from Nd:YAG-Nd:glass hybrid amplifiers. After compression, we obtained a final output of 570-mJ-155-fs pulses with a peak power of 3.67 TW, which is the highest output power from an optical parametric chirped pulse amplification laser, to the best of our knowledge.