Laser output and multiple pinches of plasma in capillary discharge

The pinch process of plasma columns generated by capillary discharge is studied theoretically with a snow-plow model. The multiple pinch evolution of plasma is obtained from the theoretical results. The effects of pressure and current amplitude on multiple pinches are calculated, and the results show that the pinch time decreases nonlinearly with decreasing pressure or increasing current. In the experiment, the laser spike of Ne-like Ar at 46.9 nm is obtained with an X-ray diode (XRD). The pressure filling in the capillary is changed to observe the variation of lasing onset time. According to real current waveforms, the pinch process is simulated. The results show that the laser spike occurs around the third pinching time. In addition, the experimental results indicate that there is an optimum pressure for the laser output.

Pinch Treatment and Photoperiod Influence Flowering of Delphinium Cultivars

Two studies were conducted to determine the influence of decapitation (pinch treatment) and photoperiod treatments on stem length, days from planting to harvest, and flowering stem yield in two delphinium cultivars. Plants of Delphinium ×belladonna Hort. ex Bergmans `Völkerfrieden' received a hard pinch (removal of apex and all stem and leaf tissue associated with leaves ≤10 cm), soft pinch (removal of apex and all stem and leaf tissue associated with leaves ≤4 cm), or no pinch. Plants of the D. elatum L. `Barbara' series were grown under either long- or short-day photoperiod, each treatment with or without receiving a soft-pinch. Time from planting to harvest was longer in pinched plants than in nonpinched plants of both cultivars regardless of photoperiod. Flowering stems were longer in hard- and soft-pinched plants of `Völkerfrieden' compared to nonpinched plants, and with `Barbara', stem length of pinched plants was either longer or similar to that of nonpinched plants regardless of photoperiod. At 30 days after the commencement of harvest, yield of flowering stems for hard-pinched plants of `Völkerfrieden' was higher than that for nonpinched plants, but yield from soft-pinched plants was similar to that for those not pinched. Stem yield for `Barbara' was higher for pinched plants under the long-day photoperiod, but under short days, yield from pinched plants was similar to that for those not pinched. Long days appear to increase yield and reduce production time in delphinium cultivars. Commercial benefits may be realized by growing nonpinched plants for earliness and pinched plants for longer stems and higher yield.