X-ray pulses (full width at half maximum ∼ 90 ns, dose rate ∼ 107 Gy s−1) were used to irradiate ... more X-ray pulses (full width at half maximum ∼ 90 ns, dose rate ∼ 107 Gy s−1) were used to irradiate the monolayer of peripheral blood mononucleated cells using the PF-2kJ kilojoule plasma focus device. Four different exposure conditions were evaluated using 5, 10, 20, and 40 pulses, with the mean dose measured by TLD-100 being 0.12 ± 0.02 mGy, 0.14 ± 0.03 mGy, 0.22 ± 0.06 mGy, and 0.47 ± 0.09 mGy, respectively. Cytogenetic analysis showed an increase in all types of chromosomal aberrations following exposure to x-ray pulses. The distribution of dicentrics and centric rings was overdispersed after 5, 10, 20, and 40 pulses. Additionally, after 20 and 40 pulses, the presence of tricentric chromosomes is detected. Chromosome aberration frequencies found in this study were always higher than the estimated frequencies of chromosome aberrations using published dose–effect curves for conventional radiation sources. The overdispersion observed, the elevated maximum relative biological effective...
The following ideas are widely accepted in Chile with respect to scientific activity: is carried ... more The following ideas are widely accepted in Chile with respect to scientific activity: is carried out mainly in universities and science is considered a naturally university activity, that was developed in a period of more than 150 years by isolated individual efforts, c) it was transformed into an institutionalized activity at the universities after the university reform movement at the end of the 1960 decade, d) the activity is finally institutionalized in the country with the creation of the "Comision Nacional de Investigation Cientifica y Tecnologica, CONICYT (National Commission for Scientific and Technological Research) in 1967. This work presents preliminary findings showing that there are other institutional initiatives, different to the efforts from universities and directly dependent of the Chilean Government, in order to produce science and technology in Chile. This governmental initiatives start at the beginning of the Republic of Chile circa of 1810.
En este trabajo se presenta la comparacion entre simulaciones numericas de descargas en el dispos... more En este trabajo se presenta la comparacion entre simulaciones numericas de descargas en el dispositivo Plasma Focus llamado PF-50J utilizando el codigo CShock. El codigo fue capaz de reproducir las mediciones de la cinematica y de los parametros del circuito electrico asi como la inestabilidad particular que se produce en la lamina de corriente observada en este dispositivo en particular.
The potentiality of the digital holography technique applied to transparent objects is discussed ... more The potentiality of the digital holography technique applied to transparent objects is discussed in terms of the set of refractive optical diagnostics (Interferometry, Shadowgraphy and Schlieren technique), which can be reconstructed with a single interferometric record.
Lecture notes in electrical engineering, Nov 28, 2019
Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radia... more Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radiation and particle beams. One of them is the dense plasma focus, a device that has renewed interest for physics research and possible industrial applications. In this work, the evaluation of UHF antennas is carried out as an alternative remote diagnostic of this device. The measurements were taken from a low energy dense plasma focus device PF-400J operating at 26 kV of charging voltage and using hydrogen at a pressure of 9.5 mbar. The device operation was simultaneously measured with an inductive sensor, an inductive sensor loop, and an antenna. Two antennas were used for evaluating which one of them could be used as a complementary diagnostic of the device operation: a monopole and a Vivaldi antenna. Both antennas were tuned in the UHF range and were previously designed for measuring partial discharge phenomena. The characterization of the device operation with the antennas was carried out comparing the time domain signals of the antennas and the inductive sensor, whose signals features had been known beforehand. Then, for quantifying both types of measurements, signal parameters of the inductive sensor and the antennas were correlated. Peak value and signal energy were determined from the antennas signal and they were correlated with the dip value feature of the inductive sensor which is an important indicator of the plasma dynamic of the discharge. The results indicate that antennas can be used for the detection of abrupt changes in the circuit current of the device. In particular, the plasma maximum compression, known as pinch, could be inferred from the antenna signal as a transient that started when the dip feature was detected with an inductive measurement. The correlation between antenna signals parameter and the dip value of the inductive sensor showed high data dispersion, although an increasing trend of the antennas signal parameter with dip values was found. This work, as an initial experimental survey, concluded that UHF measurement techniques can be applied to the remote diagnostic of pulsed plasma discharges. The understanding of the emitting mechanism of the device and proper design of UHF sensors will be considered in future work.
Plasma Focus (PF) devices as well as other similar pulsed discharge devices requires a variety of... more Plasma Focus (PF) devices as well as other similar pulsed discharge devices requires a variety of diagnostics for their proper control and optimization, including the voltage between electrodes, the time derivative of the discharge current, detection of X-rays and neutron emissions, and pulsed laser images (Shadow, Schlieren, interferograms). This article discusses the problem of the time reference of all these outputs and proposes specific techniques for synchronizing them based on sound physical grounds. The foundations of synchronization criterion are verified in several experiments on PF devices.
In this work, new evidence and information about both the origin and evolution of filamentary str... more In this work, new evidence and information about both the origin and evolution of filamentary structures observed in the current sheath of a small plasma focus (PF) discharge are reported. The experiments were carried out in a small generator of low energy (multipurpose generator) at the PF configuration, under different operating conditions. These include different anode and insulator geometries, without return bars and in a high-performance regime of the generator at high pressures ( > 10 mbar). The evolution of the plasma structures is characterized by means of refractive optical techniques. The electrical behavior of the discharge, as well as its performance, are monitored with conventional electrical diagnostics and neutron and x-ray detectors, respectively. Plasma filaments of the same species are present in all tested configurations, however, in experiments with larger effective anode length (and smaller anode radii), the plasma region containing the filaments moves away f...
In the present work, a kilojoule plasma focus device, PF-2 kJ, is adopted as a pulsed x-ray sourc... more In the present work, a kilojoule plasma focus device, PF-2 kJ, is adopted as a pulsed x-ray source to study the effects of pulsed radiation in cancer cells. Low dose hyper-radiosensitivity (LDHRS) effects have been explored in various cancer cell lines using conventional x-ray irradiation. To the best of our knowledge, the LDHRS effects have not yet been explored using pulsed x-rays. Cell death was evaluated in human colorectal (DLD-1 and HCT-116) and breast (MCF-7) cancer cell lines (monolayer cell cultures) irradiated with 10 (∼0.24 Gy), 20 (0.61 Gy), and 40 (∼1.1 Gy) pulses (FWHM ∼ 90 ns, dose rate ∼107 Gy/min with a dose of 0.025 Gy per pulse). The LDHRS cell death effect in the DLD-1 cell line irradiated with pulsed x-ray is three times higher than the reported for a conventional continuous x-ray source at two times higher doses. LDHRS was also observed in HCT-116 and MCF-7 cells exposed to 10 and 20 x-ray pulses, respectively, which are reported not to exhibit LDHRS when conve...
Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radia... more Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radiation and particle beams. One of them is the dense plasma focus, a device that has renewed interest for physics research and possible industrial applications. The plasma produced with this device corresponds to the z-pinch phenomena and lasts between 1–10 ns. Electrical quantities such as the voltage across the electrodes of the vacuum chamber where the plasma dynamic takes place and the circuit current are used for the diagnostic of these devices. The short duration of the high density plasma that is produced implies a challenge when choosing a proper sensor. Typically, Rogowski coils wrapped around a conductor are used for measuring the time derivative of the circuit current. The reproducibility of Rogowski coils and variation of its frequency response due to movements can be an issue. An inductive loop sensor was developed as an alternative to measure fast and low amplitude transients of partial discharges. In this work, the use of the inductive loop sensor is proposed as an alternative sensor for the dense plasma focus operation measurement. Simultaneous measurements of both the Rogowski coil and inductive loop sensor were carried out on a low energy dense plasma focus. A comparison between both sensors was made in time and time-frequency domains. Wavelet transform was used in the time-frequency analysis. Further studies regarding the pinch detection were made with correlations between the signal values at this particular instant of the device operation. The results indicated that similar results in the characterization of the dense plasma focus operation can be obtained with the inductive loop sensor. In terms of the frequency response at time of pinch both sensors yielded similar results. A linear tendency between the signal values at time of pinch was found. Future work will be carried out to fully adapt the inductive loop sensor for its application in pulsed power technology.
Abstract Plasma focus devices have been investigated as a pulsed radiation source. Different stud... more Abstract Plasma focus devices have been investigated as a pulsed radiation source. Different studies have shown that the shape of the anode affects strongly the plasma dynamic and x-ray emission that takes place in plasma focus devices. In the present work, a hybrid-type plasma focus device (6 μ F, 16 ± 1 kV), named PF-2kJ, is operated at various pressures of hydrogen gas with five cylindrical anodes of the same lengths but different in shapes, without cathode bars. The effect of cathode bars on various electric parameters is studied for the anode that has the maximum x-ray emission. The electrical signals of Rogowski coil (current derivative), voltage divider (voltage at the anode), and photomultiplier tubes (X-rays) were analyzed for all the anodes. Inductance and the voltage at the time of the pinch were derived from the measured voltage and current derivative signals. The x-ray dose measurements were performed using thermoluminescent dosimeters (TLD-100). The PF-2kJ performance is not the best while using the cathode bars. Our results show that by changing the anode shape just over the insulator sleeve the plasma focus devices can be switched between close energies stored in the capacitor bank.
The use of particular designations of countries or territories does not imply any judgement by th... more The use of particular designations of countries or territories does not imply any judgement by the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA. 23 rd IAEA Technical Meeting on Research Using Small Fusion Devices 29 th-31 st March,
X-ray pulses (full width at half maximum ∼ 90 ns, dose rate ∼ 107 Gy s−1) were used to irradiate ... more X-ray pulses (full width at half maximum ∼ 90 ns, dose rate ∼ 107 Gy s−1) were used to irradiate the monolayer of peripheral blood mononucleated cells using the PF-2kJ kilojoule plasma focus device. Four different exposure conditions were evaluated using 5, 10, 20, and 40 pulses, with the mean dose measured by TLD-100 being 0.12 ± 0.02 mGy, 0.14 ± 0.03 mGy, 0.22 ± 0.06 mGy, and 0.47 ± 0.09 mGy, respectively. Cytogenetic analysis showed an increase in all types of chromosomal aberrations following exposure to x-ray pulses. The distribution of dicentrics and centric rings was overdispersed after 5, 10, 20, and 40 pulses. Additionally, after 20 and 40 pulses, the presence of tricentric chromosomes is detected. Chromosome aberration frequencies found in this study were always higher than the estimated frequencies of chromosome aberrations using published dose–effect curves for conventional radiation sources. The overdispersion observed, the elevated maximum relative biological effective...
The following ideas are widely accepted in Chile with respect to scientific activity: is carried ... more The following ideas are widely accepted in Chile with respect to scientific activity: is carried out mainly in universities and science is considered a naturally university activity, that was developed in a period of more than 150 years by isolated individual efforts, c) it was transformed into an institutionalized activity at the universities after the university reform movement at the end of the 1960 decade, d) the activity is finally institutionalized in the country with the creation of the "Comision Nacional de Investigation Cientifica y Tecnologica, CONICYT (National Commission for Scientific and Technological Research) in 1967. This work presents preliminary findings showing that there are other institutional initiatives, different to the efforts from universities and directly dependent of the Chilean Government, in order to produce science and technology in Chile. This governmental initiatives start at the beginning of the Republic of Chile circa of 1810.
En este trabajo se presenta la comparacion entre simulaciones numericas de descargas en el dispos... more En este trabajo se presenta la comparacion entre simulaciones numericas de descargas en el dispositivo Plasma Focus llamado PF-50J utilizando el codigo CShock. El codigo fue capaz de reproducir las mediciones de la cinematica y de los parametros del circuito electrico asi como la inestabilidad particular que se produce en la lamina de corriente observada en este dispositivo en particular.
The potentiality of the digital holography technique applied to transparent objects is discussed ... more The potentiality of the digital holography technique applied to transparent objects is discussed in terms of the set of refractive optical diagnostics (Interferometry, Shadowgraphy and Schlieren technique), which can be reconstructed with a single interferometric record.
Lecture notes in electrical engineering, Nov 28, 2019
Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radia... more Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radiation and particle beams. One of them is the dense plasma focus, a device that has renewed interest for physics research and possible industrial applications. In this work, the evaluation of UHF antennas is carried out as an alternative remote diagnostic of this device. The measurements were taken from a low energy dense plasma focus device PF-400J operating at 26 kV of charging voltage and using hydrogen at a pressure of 9.5 mbar. The device operation was simultaneously measured with an inductive sensor, an inductive sensor loop, and an antenna. Two antennas were used for evaluating which one of them could be used as a complementary diagnostic of the device operation: a monopole and a Vivaldi antenna. Both antennas were tuned in the UHF range and were previously designed for measuring partial discharge phenomena. The characterization of the device operation with the antennas was carried out comparing the time domain signals of the antennas and the inductive sensor, whose signals features had been known beforehand. Then, for quantifying both types of measurements, signal parameters of the inductive sensor and the antennas were correlated. Peak value and signal energy were determined from the antennas signal and they were correlated with the dip value feature of the inductive sensor which is an important indicator of the plasma dynamic of the discharge. The results indicate that antennas can be used for the detection of abrupt changes in the circuit current of the device. In particular, the plasma maximum compression, known as pinch, could be inferred from the antenna signal as a transient that started when the dip feature was detected with an inductive measurement. The correlation between antenna signals parameter and the dip value of the inductive sensor showed high data dispersion, although an increasing trend of the antennas signal parameter with dip values was found. This work, as an initial experimental survey, concluded that UHF measurement techniques can be applied to the remote diagnostic of pulsed plasma discharges. The understanding of the emitting mechanism of the device and proper design of UHF sensors will be considered in future work.
Plasma Focus (PF) devices as well as other similar pulsed discharge devices requires a variety of... more Plasma Focus (PF) devices as well as other similar pulsed discharge devices requires a variety of diagnostics for their proper control and optimization, including the voltage between electrodes, the time derivative of the discharge current, detection of X-rays and neutron emissions, and pulsed laser images (Shadow, Schlieren, interferograms). This article discusses the problem of the time reference of all these outputs and proposes specific techniques for synchronizing them based on sound physical grounds. The foundations of synchronization criterion are verified in several experiments on PF devices.
In this work, new evidence and information about both the origin and evolution of filamentary str... more In this work, new evidence and information about both the origin and evolution of filamentary structures observed in the current sheath of a small plasma focus (PF) discharge are reported. The experiments were carried out in a small generator of low energy (multipurpose generator) at the PF configuration, under different operating conditions. These include different anode and insulator geometries, without return bars and in a high-performance regime of the generator at high pressures ( > 10 mbar). The evolution of the plasma structures is characterized by means of refractive optical techniques. The electrical behavior of the discharge, as well as its performance, are monitored with conventional electrical diagnostics and neutron and x-ray detectors, respectively. Plasma filaments of the same species are present in all tested configurations, however, in experiments with larger effective anode length (and smaller anode radii), the plasma region containing the filaments moves away f...
In the present work, a kilojoule plasma focus device, PF-2 kJ, is adopted as a pulsed x-ray sourc... more In the present work, a kilojoule plasma focus device, PF-2 kJ, is adopted as a pulsed x-ray source to study the effects of pulsed radiation in cancer cells. Low dose hyper-radiosensitivity (LDHRS) effects have been explored in various cancer cell lines using conventional x-ray irradiation. To the best of our knowledge, the LDHRS effects have not yet been explored using pulsed x-rays. Cell death was evaluated in human colorectal (DLD-1 and HCT-116) and breast (MCF-7) cancer cell lines (monolayer cell cultures) irradiated with 10 (∼0.24 Gy), 20 (0.61 Gy), and 40 (∼1.1 Gy) pulses (FWHM ∼ 90 ns, dose rate ∼107 Gy/min with a dose of 0.025 Gy per pulse). The LDHRS cell death effect in the DLD-1 cell line irradiated with pulsed x-ray is three times higher than the reported for a conventional continuous x-ray source at two times higher doses. LDHRS was also observed in HCT-116 and MCF-7 cells exposed to 10 and 20 x-ray pulses, respectively, which are reported not to exhibit LDHRS when conve...
Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radia... more Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radiation and particle beams. One of them is the dense plasma focus, a device that has renewed interest for physics research and possible industrial applications. The plasma produced with this device corresponds to the z-pinch phenomena and lasts between 1–10 ns. Electrical quantities such as the voltage across the electrodes of the vacuum chamber where the plasma dynamic takes place and the circuit current are used for the diagnostic of these devices. The short duration of the high density plasma that is produced implies a challenge when choosing a proper sensor. Typically, Rogowski coils wrapped around a conductor are used for measuring the time derivative of the circuit current. The reproducibility of Rogowski coils and variation of its frequency response due to movements can be an issue. An inductive loop sensor was developed as an alternative to measure fast and low amplitude transients of partial discharges. In this work, the use of the inductive loop sensor is proposed as an alternative sensor for the dense plasma focus operation measurement. Simultaneous measurements of both the Rogowski coil and inductive loop sensor were carried out on a low energy dense plasma focus. A comparison between both sensors was made in time and time-frequency domains. Wavelet transform was used in the time-frequency analysis. Further studies regarding the pinch detection were made with correlations between the signal values at this particular instant of the device operation. The results indicated that similar results in the characterization of the dense plasma focus operation can be obtained with the inductive loop sensor. In terms of the frequency response at time of pinch both sensors yielded similar results. A linear tendency between the signal values at time of pinch was found. Future work will be carried out to fully adapt the inductive loop sensor for its application in pulsed power technology.
Abstract Plasma focus devices have been investigated as a pulsed radiation source. Different stud... more Abstract Plasma focus devices have been investigated as a pulsed radiation source. Different studies have shown that the shape of the anode affects strongly the plasma dynamic and x-ray emission that takes place in plasma focus devices. In the present work, a hybrid-type plasma focus device (6 μ F, 16 ± 1 kV), named PF-2kJ, is operated at various pressures of hydrogen gas with five cylindrical anodes of the same lengths but different in shapes, without cathode bars. The effect of cathode bars on various electric parameters is studied for the anode that has the maximum x-ray emission. The electrical signals of Rogowski coil (current derivative), voltage divider (voltage at the anode), and photomultiplier tubes (X-rays) were analyzed for all the anodes. Inductance and the voltage at the time of the pinch were derived from the measured voltage and current derivative signals. The x-ray dose measurements were performed using thermoluminescent dosimeters (TLD-100). The PF-2kJ performance is not the best while using the cathode bars. Our results show that by changing the anode shape just over the insulator sleeve the plasma focus devices can be switched between close energies stored in the capacitor bank.
The use of particular designations of countries or territories does not imply any judgement by th... more The use of particular designations of countries or territories does not imply any judgement by the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA. 23 rd IAEA Technical Meeting on Research Using Small Fusion Devices 29 th-31 st March,
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