The Thailand Plasma Focus II (TPF-II) is a 3.3 kJ dense plasma focus that was developed at Walailak University, Thailand. The aim of the device is to study the production of ion beams in the keV energy range and their applications for the color modification of gemstones. A high-energy ion beam is produced by heating and acceleration in the pinch phase of the plasma focus. The heating process is determined by the maximum electrical current, which can be optimized by variation of the system’s inductance. Lee model code was implemented to optimize the configuration of the electrodes. The current waveforms for the different initial conditions were used to obtain the system’s inductance, which was verified by a short circuit test. It was found that the inductance and resistance were about 153 nH and 12 mΩ, respectively.
We have designed and constructed a spectroscopic interferometer, and test run its operation with a pulsed discharge plasma. The plasma is produced by capacitor discharge across a gap filled with neutral argon at selected pressures. Ablation of iron from the cathode adds to argon to form equilibrium plasma of an argon-iron mixture. The ablative mass addition is measured and incorporated into the system of Saha equations. The calculated plasma energy is compared to independently measured total energy injected into the plasma to determine the peak plasma temperature. The measured coherence length of an argon emission line shows a dependence on the direction of the line of sight and a scaling with collision time within the plasma.
Dielectric barrier discharge (DBD) plasma treatment has been reported to increase the quality of seeds and seedlings. In order to improve sprout quality, this study was conducted to investigate the effect of DBD plasma treatment on seed germination, vigour, growth, and bioactive compound content of sunflower (Helianthus annuus) sprouts. Two sunflower cultivars, Arfael and Jumbo, were treated using atmospheric DBD plasma at a discharge voltage of 20 kV for 15, 30, 60, 120, and 240 s. The non-treated seeds were used as control. The responses of seeds to the treatment depended on the exposure time and the cultivar. While the treatment stimulated seed germination and improved the vigour of the Jumbo cultivar at all exposure times, the Arfael cultivar responded only to exposures of 60 s, 120 s, and 240 s. Sprouts derived from 60 s, 120 s, and 240 s DBD plasma treatments exhibited greater dry weight than those from other treatments. Moreover, the Arfael sprouts showed a higher bioactive compound level than the Jumbo sprouts. The DBD plasma treatments of both cultivars for 120 s and 240 s enhanced the accumulation of total phenolics and flavonoids. However, plasma treatment did not affect DPPH radical scavenging. The results from this study indicate that the 120 s DBD plasma treatment is effective in enhancing seed germination, growth, and bioactive compound of sunflower sprouts. This study is the first of its kind to illustrate the potential benefits of the DBD plasma treatment to enhance the quality of sunflower sprouts.
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