The Collective Thomson scattering technique has been implemented to study the stagnation of a single liner gas-puff. The plasma parameters are determined by theoretically modelling the scattering ...form factor in combination with Bayesian inference to provide the set of the most probable parameters that describe the experimental data. Analysis of the data reveal that incoming flows are able to interpenetrate partially. Estimation of the mean free path shows a gradual transition from a weakly collisional to a collisional regime as the plasma gets to the axis. Furthermore, we find that the ion energy at Formula: see text is Formula: see text and is mostly kinetic in nature and represents Formula: see text of the total energy. This kinetic energy is far greater than the value on axis of Formula: see text which is Formula: see text of the total energy. Energy transfer to the electrons and radiation losses are found to be negligible by this time. A possible explanation for this energy imbalance is the presence of an azimuthal magnetic field larger than Formula: see text that deflect the ions vertically. The uncertainties quoted represent 68% credible intervals.
Present work is aimed to perform dosimetric measurements to characterize dosis obtained from pulsed x-rays emitted from a hundred joules plasma focus device PF-400J using thermoluminescent dosimeters ...(TLD-100). Two dosimeter arrays (containing 21 dosimeters in each) were used. One of the arrays was kept inside the PF-400J vacuum chamber and other outside the vacuum chamber, simultaneously. It was found that dosis obtained from the inside array (∼200.7 mGy) were hundred times larger than the outside array (∼1.1 mGy) for hundred pulses of x-rays. Later, the vacuum window of PF-400J, which was made of 1 mm aluminum, was replaced by a plastic window and a similar dosimeter array was kept outside the chamber over the plastic window. With this arrangement, the obtained doses (100 pulses of x-rays) were of the same order of magnitude (∼106 mGy) as it was inside the vacuum chamber. Later, a lead piece was inserted inside the hollow anode of PF-400J, which increased dose (∼250 mGy) per hundred pulses of x-ray outside the vacuum chamber using plastic vacuum window. Our results suggest that PF-400J could be a useful device to study low dose pulsed radiation effects on cancer cell lines in in vitro experiments.
In the last years, pulsed reduced low dose radiation has been proposed as an alternative for treatment of recurrent cancer. Nonetheless, distinction between the effects of low dose pulsed and ...continuous radiation is barely known at cellular level. In order to study the effects of low dose pulsed radiation at cellular level, in vitro experiments are important to further advance the basic understanding in this area. In the present work we demonstrate the usefulness of a low-energy plasma focus device PF-400J as a potential source of low-dose pulsed radiation for in vitro cancer cell experiments. Colorectal cancer cell line, DLD-1, were irradiated by pulsed x-rays. Fifty pulses of x-rays provide ∼0.12 Gy dosis, which were measured using thermoluminescence detectors (TLD-100 dosimeters). Irradiation-induced DNA damage was assessed at different time points after irradiation. A statistically significant double strand break (DSB) DNA damage was observed at 30 minutes after irradiation. A comparison of DSB induced by continuous source in the same type cancer cells and pulsed irradiation is made at 30 minutes post-irradiation. In the case of pulsed irradiation, DSB per unit dose found higher. Our findings suggest that low-energy plasma focus devices could have potential application as pulsed radiation source in the area of in vitro cancer cell experiments.
We present the study of the evolution of the ionization degree of the plasma sheath in a low energy plasma focus device with time and spatial resolution, by means of visible spectroscopy. The ...measurements were developed in the low energy plasma focus device PF-400J (176-539 J, 880 nF, 20-35 kV, quarter period ∼300 ns) 1, using an ANDOR Shamrock 500i visible spectrometer with an ICCD that enabled the acquisition of spectra with time resolution in the order of tens of nanosecond. The use of a lens system improved spatial resolution, allowing the study of the plasma sheath in different stages of the discharge dynamic. In this work we present results from the pinch volume to study the evolution of the ionization degree of the plasma. The results include discharges in pure Hydrogen and a mixture of noble gases and Hydrogen, such as Neon and Helium, which were introduced in the discharge by small percentages ranging from 2 to 5%.
Spectral measurements in the visible range of the plasma sheath ionization degree evolution on the plasma focus device PF-400J are presented. The measurements were done with temporal and spatial ...resolution in a plasma focus device of low stored energy: PF-400J (176-539 J, 880 nF, 20-35 kV, quarter period ∼ 300ns) 1. An ICCD was attached to a 0.5 m focal length visible spectrometer, which enabled the acquisition of time resolved spectrum with 20 ns integration time throughout the whole current pulse evolution. The spatial resolution was attained using a set of lenses which allowed the focusing of a small volume of the plasma sheath in different positions of the inter-electrode space. Discharges were carried out in mixtures of Hydrogen with gases in different proportions: 5% Neon, 5% Krypton and 2% Nitrogen. Discharges using Neon as an impurity showed no ionization of the gas, just a very low intensity emission of Ne I at times much larger than the maximum current. Nitrogen, on the other hand, showed a high ionization reaching N V (N4+) at the end of the axial phase, with a distinctive evolution of the ionization degree as the plasma sheath moved towards the end of the electrodes. A mixed result was found when using Krypton, since the ionization degree only reached levels around Kr II III, even though it has an ionization potential lower than Neon.
Plasma focus devices may arise as useful source to perform experiments aimed to study the effects of pulsed radiation on human cells in vitro. In the present work, a table top hundred joules plasma ...focus device, namely “PF-400J”, was adapted to irradiate colorectal cancer cell line, DLD-1. For pulsed x-rays, the doses (energy absorbed per unit mass, measured in Gy) were measured using thermoluminescence detectors (TLD-100 dosimeters). The neutron fluence and the average energy were used to estimate the pulsed neutron doses. Fifty pulses of x-rays (0.12 Gy) and fifty pulses of neutrons (3.5 μGy) were used to irradiate the cancer cells. Irradiation-induced DNA damage and cell death were assessed at different time points after irradiation. Cell death was observed using pulsed neutron irradiation, at ultralow doses. Our results indicate that the PF-400J can be used for in vitro assessment of the effect of pulsed radiation in cancer cell research.
In present work an effort has been made to measure the ion beams generated during experiment with PF-400J plasma focus device, using an array of two Rogowski coils with time of flight analysis. It ...was found that the coils measure the signals of beam for a particular range of operating pressure. The beam signals were recorded at 20, 15, 12, 10, 9,8,7,6 and 5 mbar filled pressure of hydrogen gas. The optimized pressure range for good plasma column formation for this device was found about 9 mbar. At 15 mbar no or very weak beam signals were observed by Rogowski coil which was kept relatively far from the top of the anode and at 20 mbar there were no beam signals observed in both of the coils. The calculated beam energy is found to have maximum value at 9 mbar of filled hydrogen gas pressure.
With the purpose to study the effects of pulsed x-rays radiation on cancer cells, the total doses of x-ray pulses and the temporal duration of the pulse has been characterized in a hundred joules ...plasma focus device (PF-400J, 130 kA achieved in 300ns, 30 kV, 880 nF, 38 nH). TLD dosimeters were located outside of the discharge chamber, at 96 mm from the anode top. In addition, two photomultipliers with plastic scintillator were located in axial and radial directions. From the statistical analysis of the TLD and photomultiplier signals, was possible to estimate that a single shot has a total dose of the order of 30±15 µSv with a duration of the order of 12±3.6 ns at FWHM. Preliminary experiments using MCF7, a breast cancer cell line, were performed. Cells were irradiated at 96 mm from the anode top with 300 cumulative x-ray shots and cell proliferation was evaluated at 24, 48 and 72 hours later.
Different studies have been developed in order to understand the dynamics and processes involved in the particle emission from plasma focus devices operating in the kilojoule range. The use of ...chemical compound gasses and noble gas mixtures has proven to produce different charged particles, as well as increase the neutron yield from deuterium plasma discharges. Nevertheless, the processes and parameters involved in these discharges are not fully understood. In this work we will present results of visible spectroscopy and "time-of- flight" observations of the different ion species and ionization levels obtained in a 2kJ plasma focus device, when using deuterium or hydrogen with small percentage impurities.
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