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Radiation Physics and Chemistry (0969806X) 226
In this study, the instrumental neutron activation analysis (INAA) process has been simulated using Monte Carlo method in three steps at Isfahan Miniature Neutron Source Reactor (MNSR), and simulation results have been validated by experiments. The thermal neutron flux at the inner irradiation channel of the reactor and the effective multiplication factor (keff) of the reactor have been investigated by both Monte Carlo simulations and experiments. The Certified Reference Material (CRM) LKSD-4 geology sample has been irradiated in the inner irradiation channel for 60 s, and the gamma spectrum of the activated sample have been measured for 500s after52 s cooling time. The gamma spectrum has been obtained by the HPGe detector. The corrections related to the background spectrum and the detector resolution have been calculated and applied to the results. An experiment has been performed in the similar condition, and the results have been compared with the simulation. The results have showed an acceptable confirmation between experiment and simulation. This method can be used as an effective tool for prediction of the INAA procedure before performing the real analyze on the samples. © 2024 Elsevier Ltd
Farokhi, F. ,
Shirani bidabadi, B. ,
Fattori, S. ,
Asgarian, M.A. ,
Cuttone, G. ,
Jia, S.B. ,
Petringa, G. ,
Sciuto, A. ,
Pablo cirrone g.a., Radiation Physics and Chemistry (18790895) 212
FLASH radiotherapy (or FLASH-RT) is a novel radiotherapy technology consisting of radiation delivery at dose rates several orders of magnitude higher (≥40Gy/s) than the currently used in conventional clinical radiotherapy. Many recent in-vivo preclinical studies indicate that FLASH-RT can greatly spare healthy tissues while maintaining unchanged tumour control. The generally acknowledged, though not entirely substantiated, explanation for the FLASH effect relates to the oxygen depletion that occurs after the radiation passage. On the other hand, oxygen depletion or, more in general, oxygen-related effects are still not fully clarified. Different research groups carried out the Monte Carlo simulations of electron and proton irradiations in oxygenated water to evaluate the oxygen-concentration-related effects at the cell-scale level. We analysed and compared the simulation results of the oxygen effect under the FLASH condition (considering the time-dependent G-values and the oxygen enhancement ratio-weighted dose) we obtained with GEANT4-DNA against TRAX-CHEM code results in the literature. Our results indicate that oxygen depletion has a negligible effect on radiosensitivity via oxygen enhancement, showing a close agreement with the TRAX-CHEM code. The conclusion is that the Geant4-DNA toolkit can be a valid instrument to study the FLASH effect. © 2023 Elsevier Ltd
Applied Radiation and Isotopes (09698043) 193
In this study, the effects of irradiation by proton beam of a plasma focus device with 5 kJ discharge energy on photovoltaic (PV) cells were investigated. Before and after irradiation, the I–V curve of the cells was measured. Changes in Voc and Isc of silicon-type PV cells were recorded. After 1, 2, 4 and 8 shots, on average compared to the initial conditions, the voltage decreased by 76.81%, 76.70%, 84.94% and 83.74% respectively, and the current decreased by 43.18%, 54.91%, 67.49% and 58.07% respectively. The behavior of the plasma focus device was simulated by the LEE code, and the damage caused by the protons of the plasma focus device in each shot was evaluated by SRIM & TRIM software. For each shot of the plasma focus device, on average, about 3.82% of the atoms were displaced. The recovery time of the crystal structure, and the improvement of photovoltaic cells’ properties after irradiation were investigated experimentally. After 10 days of irradiation, the open circuit voltage of the cells that were irradiated by 1, 2 and 4 shots were increased by 22.81, 18.00 and 35.10%, respectively. Also, the short-circuit current of the cells were increased by 7.37, 8.91 and 27.89%, respectively. © 2023 Elsevier Ltd
Journal of Instrumentation (17480221) 17(11)
Electron linear accelerator (LINAC) is a high-energy X-ray generator with extensive industrial, inspection, and medical applications. The studied LINAC uses a 2.6 MW magnetron as its RF generator derived with a Marx modulator. An electron gun of filament voltage 6 V and current 2.2 A connected to the accelerator tube is applied to establish electron current inside the drift tube. For this purpose, 9 kV and 25 kV voltages are applied to the cathode and anode of the electron gun pulse by pulse, generating dual-energy x-ray beams as outputs. An Automatic Frequency Control (AFC) system is designed for studied LINAC so that variation of output dose rate is lower than 2% and the required time to achieve the maximum output dose rate is lower than 1 s. Optimizing the Marx modulator's switching algorithm, the ripple in the output beam has been lower than 5%. The half-value layer (HVL) of steel has been measured for high and low energies equal to 6 MeV and 3 MeV, respectively. The output pulse of the electron beam and dose rate have been measured using a linear detector array (LDA) and dosimeter, respectively, with a pulse frequency of 35-400 Hz and pulse width of 2-4 μs. © 2022 IOP Publishing Ltd and Sissa Medialab.
Nuclear Engineering and Technology (2234358X) 53(1)pp. 266-272
In the pulsed electron beam generators, such as plasma focus devices and linear induction accelerators whose electron pulse width is in the range of nanosecond and less, as well as in cases where there is no direct access to electron beam, like runaway electrons in Tokamaks, measurement of the electron energy spectrum is a technical challenge. In such cases, the indirect measurement of the electron spectrum by using the bremsstrahlung radiation spectrum associated with it, is an appropriate solution. The problem with this method is that the matrix equation between the two spectrums is an ill-conditioned equation, which results in errors of the measured X-ray spectrum to be propagated with a large coefficient in the estimated electron spectrum. In this study, a method based on the neural network and the MCNP code is presented and evaluated to recover the electron spectrum from the X-ray generated by collision of the electron beam with a target. Multilayer perceptron network showed good accuracy in electron spectrum recovery, so that for the X-ray spectrum with errors of 3% and 10%, the network estimated the electron spectrum with an average standard error of 8% and 11%, on all of the energy intervals. © 2020 Korean Nuclear Society
Nuclear Engineering and Technology (17385733) 52(4)pp. 827-834
Damage of tungsten due to helium ions of a PF device was studied. The tungsten was analyzed by SEM and AFM after irradiation. SEM revealed fine bubbles of helium atoms with diameters of a few nanometers, which join and form larger bubbles and blisters on the surface of tungsten. This observation confirmed the results of molecular dynamics simulation. SEM analysis after etching of the irradiated surface indicated cavities with depth range of 35–85 nm. The average fluence of helium ion of the PF device was calculated about 5.2 × 1015 cm−2 per shot, using Lee code. Energy spectrum of helium ions was estimated using a Thomson parabola spectrometer as a function of dN/dE ∝ E−2.8 in the energy range of 10–200 keV. The characteristics of helium ion beam was imported to SRIM code. SRIM revealed that the maximum DPA and maximum helium concentration occur in the depth range of 20–50 nm. SRIM also showed that at depth of 30 nm, all of the tungsten atoms are displaced after 20 shots, while at depth of higher than 85 nm the destruction is insignificant. There is a close match between SRIM results and the measured depths of cavities in SEM images of tungsten after etching. © 2019
Nuclear Engineering and Technology (2234358X) 52(11)pp. 2535-2542
To understand the fundamental parameters of Alvand tokamak, A Rogowski coil with an active integrator was designed and constructed. Considering the characteristics of the Alvand tokamak, the structural and electrical parameters affecting the sensor function, were designed. Calibration was performed directly in the presence of plasma. The sensor has a high resistance against interference of external magnetic fields. Plasma current was measured in various experiments. Based on the plasma current profile and loop voltage signal, the time evolution of plasma discharge was investigated and plasma behavior was analyzed. Alvand tokamak discharge was divided into several regions that represents different physical phenomena in the plasma. During the plasma discharge time, plasma had significant changes and its characteristic was not uniform. To understand the plasma behavior in each of the phases, the Rogowski sensor should have sufficient time resolution. The Rogowski sensor with a frequency up to 15 kHz was appropriate for this purpose. © 2020 Korean Nuclear Society
Radiation Physics and Engineering (26456397) 1(2)pp. 1-5
In this paper, the effect of anode’s insert material on spatial distribution of X-ray emission zone of plasma focus device was studied. Anode’s insert materials were fabricated out of aluminum, zinc, tin, tungsten and lead. For each insert material at the constant operating voltage of 21 kV, the image of pinhole camera which monitors the surface and the top of anode was recorded at the various pressures of 0.3, 0.6, 0.9 and 1.2 mbar. The results indicated that the X-ray emission zone above the anode surface not only includes thermal radiation of plasma, but also depends on anode’s insert materials. This zone could be due to the passage of high energy electrons from the vapor of anode’s material above the anode’s surface. © 2020, KN Toosi University of Technology. All rights reserved.
Fusion Engineering and Design (09203796) 160
Tungsten (W) surface damages due to high-energy irradiations of a plasma focus device, including pure Hydrogen (H) ions, pure Helium (He) ions, and 50−50 H +He mixture was assessed. W is one of the candidate materials for use in the first-wall of nuclear fusion reactors such as tokamaks. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) were utilized to analyze these damages. SEM images, in a good agreement with blister formation mechanisms proposed by large-scale atomic/molecular massively parallel simulator (LAMMPS) simulations, illustrated three different states. Due to the ability of He ions to increase the join probability of tiny blisters, the intermediate state of H+He mixture irradiation, including large individual blisters perches between two limit states of pure H and pure He irradiations, including tiny individual blisters and large clusters of blisters, respectively. AFM analyses confirm the role of He to provide the intermediate state based on values of roughness in these three states. XRD analyses show the considerable changes in the position and intensity of peaks. The shifted peak positions toward the higher angles present a mean value in the intermediate state of H+He mixture irradiation. Also, the medium peak intensity of the intermediate state clarifies the role of He in modulating the sharp behavior of H in the irradiation of W sample. The calculated compressive stresses show a moderate value for the irradiation with the H+He mixture. © 2020 Elsevier B.V.
In this paper, tungsten samples were exposed by H ions under 5, 10 and 20 PF discharges in a Mather-type plasma focus device. The hydrogen retention and the produced damage in the tungsten surface were studied. The tungsten samples were analyzed by SEM, XRD and ERDA after irradiation. The SEM micrographs showed the blisters, cracks and open bubbles on the surface of the irradiated samples. The size of the blisters increased by enhancing the number of PF discharges. The XRD pattern revealed the crack formation and propagation at the surface of the samples. The hardening and softening behavior of the exposed samples were figured out from the X-ray diffraction pattern. The ERDA was used to obtain the depth profile of hydrogen in tungsten. Ions range and the depth profile of the damage rate in the tungsten target were calculated using the SRIM code. ERDA illustrated that the highest H concentrations occurs in the target depth range of 20–60 nm whereas the SRIM simulation showed that the highest number of H ions can pierce about 60–120 nm into the tungsten sample. This discrepancy is due to the erosion. The damage rate decreases by increasing the penetrating depth. © 2020 Elsevier Ltd
Applied Radiation and Isotopes (9698043) 154
The destructive effects of proton and argon ions produced in a low energy plasma focus device on the surface of tungsten and copper were investigated. Optical microscopy, SEM, EDX, XRD and ERD analysis were performed for initial and irradiated samples. The results showed that total thermal impact under the irradiation by argon is much more significant than that by hydrogen. Sub-micrometer blisters, clusters of joined bubbles and rupture patterns were observed on the surface of copper after irradiation by argon. Micro-cracks were observed on the tungsten samples irradiated by argon, which indicate fast annealing of the molten surface. Many dense blisters and evidence of ion sputtering were observed on the surfaces irradiated by protons. Results of ERD analysis showed that the highest concentration of hydrogen is 24% in the second layer and at a depth of 20–55 nm from the tungsten surface. In the copper sample, the highest density of hydrogen was found to be 23% in the second layer and at a depth of 28–68 nm. Also, the highest penetration depth of protons into the tungsten and copper samples was 118 nm and 160 nm, respectively. © 2019 Elsevier Ltd
Radiation Physics and Chemistry (18790895) 145pp. 58-63
The effect of the anode's insert material of a plasma focus device on the properties of X-ray emission zone was studied. Inserts were fabricated out of six different materials including aluminum, copper, zinc, tin, tungsten, and lead to cover a wide range of atomic numbers. For each anode's insert material at different gas pressures and different voltages, the shape of X-ray emission zone was recorded by three pinhole cameras, which were installed on sidewall and roof of the chamber of plasma focus device. The results indicated that by changing the gas pressure and the charge voltage of capacitor, the X-ray source of plasma focus emerges with different forms as a concentrated column or conical shape with sharp or cloudy edges. These structures are in the form of a combination of plasma emission and anode-tip emission with different intensities. These observations indicate that the material of the anode-tip especially affects the structure of X-ray emission zone. © 2017 Elsevier Ltd
Applied Radiation and Isotopes (9698043) 136pp. 21-26
In this paper, effective energy of pulsed X-Ray emitted from a Mather-type plasma focus device in stored energy of 2.5 kJ with six different anode's insert materials was measured using radiographic method with attenuation filters. Since intensity and energy of X-ray beam were considerably changed with changing the insert material, the method was improved by using different filters simultaneously in all the experiments and selection of the best filter in each experiment according to the appropriate criteria. Effective energy of pulsed X-ray beam was measured 16, 28, 50, 51, 34 and 44 keV when aluminum, copper, zinc, tin, tungsten and lead were used as insert materials, and aluminum, copper, silver, silver, copper and lead were used as filters, respectively. © 2018 Elsevier Ltd
Applied Radiation and Isotopes (9698043) 141pp. 73-79
A large number of nuclear medicine radionuclides are Auger-electron-emitters and internal conversion electrons which can transmit significant doses to the patient during diagnosis. Therefore, the dosimetry of these radioisotopes is necessary for the evaluation of their biological effects and their use for treatment and targeted-radiotherapy. In this study, dosimetry calculation of a number of widely used radioisotopes in nuclear medicine was performed on a cellular scale using Geant4-DNA simulation. S-values of some of the diagnostic radioisotopes, including 123 I, 125 I, 99m Tc, 67 Ga, 201 Tl, and 111 In, were evaluated in a homogeneous spherical geometry model with unit density in which the cell and nucleus were concentric. The results revealed that S-values of these diagnostic radioisotopes were mainly greater than S-values of the radioisotope 131 I, which emits β-particles; they were lower but can be compared with 211 At (emitter of alpha particles) in the cellular scale. It shows better the importance of dosimetry calculation of diagnostic Auger-electron-emitting radioisotope in a cellular scale and their applicability in treatment. It should be noted that the S-values obtained out of the Geant4-DNA simulation are in line with the values of the other codes and the MIRD technique. © 2018 Elsevier Ltd
Journal of Fusion Energy (15729591) 36(4-5)pp. 120-126
The present study examined the formation of hot spots in the plasma column of a 3.5 kJ Mather-type plasma focus device. Experiments were performed with air and argon as operating gases at 0.2–1.5 mbar of pressures. X-ray source images were obtained using a pinhole camera with dental X-ray film as X-ray detector. The objective was to investigate the effect of the operating conditions and gas type on formation and characteristics of the hot spots. Results showed that when using air in comparison to argon, the total X-ray emission is increased and therefore, the hot spots are covered by this high intensity emission and would be observed less frequently in the image. Using metal filters to attenuate the low-energy X-rays revealed that the most energetic or the most intense radiation was emitted from the hot spots region. The images of the X-ray source obtained using argon at the middle pressures (0.4–0.6 mbar) showed both the plasma column and the photons emitted from the anode surface. A pressure of 0.8–1.5 mbar using argon was most likely to observe the hot spots. For argon gas, the 0.9 mbar was the pressure in which the hot spots were more frequently observed with high reproducibility of location and number. Measurements revealed that the typical size of a hot spot was 10–300 µm and the distance from the anode surface was 0.5–20 mm. © 2017, Springer Science+Business Media New York.
Plasma Science and Technology (10090630) 19(7)
An indirect method is proposed for measuring the relative energy spectrum of the pulsed electron beam of a plasma focus device. The Bremsstrahlung x-ray, generated by the collision of electrons against the anode surface, was measured behind lead filters with various thicknesses using a radiographic film system. A matrix equation was considered in order to explain the relation between the x-ray dose and the spectral amplitudes of the electron beam. The electron spectrum of the device was measured at 0.6 mbar argon and 22 kV charging voltage, in four discrete energy intervals extending up to 500 keV. The results of the experiments show that most of the electrons are emitted in the 125-375 keV energy range and the spectral amplitude becomes negligible beyond 375 keV. © 2017 Hefei Institutes of Physical Science, Chinese Academy of Sciences and IOP Publishing.
Applied Radiation and Isotopes (09698043) 125pp. 169-175
The current study examined the effective energy of pulsed x-rays emitted from a Mather-type plasma focus device with copper anodes at an energy range of 2–3 kJ using x-ray transmission radiography. Aluminum filters of different thicknesses and dental x-ray film were used. When air gas was used at a constant voltage of 21 kV at 0.3, 0.6, 0.9 and 1.2 mbar, the effective energy of pulsed the x-ray was 10.9, 10.7, 17.3 and 15.8 keV, respectively. At 0.6 mbar of air, as the operating voltage increased to 19, 21 and 23 kV, the effective energy of the x-ray radiation was 10.6, 10.7 and 12.4 keV, respectively. Comprehensive investigation of the characteristics of x-ray emission from plasma focus devices makes it feasible to use this device as an intensive x-ray generator for medical and industrial purposes. The present study is a part of a program which is planned to realize these applications. © 2017 Elsevier Ltd
Journal of Food Science and Technology (00221155) 54(13)pp. 4277-4283
In this study, the effect of gamma irradiation on the shelf life and properties of cucumber was investigated. These properties include weight reduction, fruit density, juice, tissue firmness, total soluble solids (TSS), total titratable acidity, chlorophyll and vitamin C, pH, marketability, flavor, frostbite and fungal effects. For this purpose, cucumbers were irradiated with dose of 2, 2.5 and 3 kGy. The exposure time was calculated by MCNP4C; the Monte Carlo particle transport code. Three types of fungi (white-Sclerotinia sclerotiorum, gray-Botrytis cinerea and olive-Cladosporium cucumerinum), were used to infect some samples. The chlorophyll and vitamin C preservation abilities were increased to about 3 and 1.4 times, respectively with irradiation treatment. Also, the shelf life was increased about 1 week, while chilling injuries is decreased. Samples’ resistance to the fungal growth was evident and the process of fungal growth on the irradiated samples was delayed up to 1 week. The best properties were obtained at the irradiation dose of 2 kGy since it had less effect on flavor, TSS and tissue firmness. © 2017, Association of Food Scientists & Technologists (India).
Iranian Journal of Physics Research (16826957) 16(3)pp. 97-101
In this study, some characteristics of a Mather type Plasma Focus (PF) device such as a discharge current, pinch time, ion flux and hard x-ray intensity has been investigated simultaneously in argon and nitrogen gases separately for various operating gas pressures and charging voltages of capacitor bank. It was observed that pinch phenomena was energy and pressure dependent in current sheath as well as ion and hard x-ray emission intensity. Optimum pressure with maximum ion flux and the most intense hard x-ray showed a nearly linear dependence on the charging voltage of the device. Maximum ion flux was estimated in the order of 1018 ions per steradian in both gases. Hard x-ray emission was registered a little after discharge current and Faraday cup (FC) signals. Also, optimum pressure for maximum ion flux was not the same as the pressure for intense hard x-rays. Hard x-ray intensity reached its peak at higher pressures. © 2016, Isfahan University of Technology. All rights reserved.
Pramana - Journal of Physics (03044289) 85(1)pp. 149-159
In the present study, X-ray emission dose characteristics from a small Mather-type PF device in various pressures of argon as the operating gas were studied. The PF device was powered by a 12 μF capacitor at 25 kV charging voltage. Time-integrated hard X-ray (HXR) emission was investigated using thermoluminescence dosimeters (TLDs). These detectors were calibrated with 60Co and 131Cs sources. Twenty-four dosimeters were placed at four different radial distances from the axis of the electrodes at the top of the anode to measure the dose spatial distribution at the top of the anode for different pressures (0.5-1.3 mbar). At each radius, six dosimeters were placed circularly with equal angular intervals on the inner surface of the device chamber. It was found that the optimum pressure for the highest yield of X-ray is 0.9 mbar. The maximum measured dose was 17 mGy per shot at the top of the anode and about 0.5 mGy per shot at 90? with respect to the anode axis. Furthermore, these results showed that the dose at each radius is symmetrical at 360? around the top of the anode, but X-ray distribution follows an anisotropical behaviour. A fast plastic scintillator was also used for time-resolved HXR detection, and a linear relation was observed between the amplitude of the scintillator-PMT signals and TLD responses.
Journal of Plasma Physics (223778) 81(2)
In this research, the effect of inserting deuterated solid target in plasma focus device 'SBUMTPF1' on neutron yield has been investigated. The deuterated target with the diameter of 2.5 cm was placed at different heights relative to the anode tip. In each height, the best place of target (where the ion density is highest) was found from observing the effects of ions struck on the aluminum samples. Also for each height, 20 shots were performed at the optimum pressure of deuterium working gas and operating voltage, which are equal to 1.5 mbar and 24 kV, respectively. The neutron production was measured with two activation counters, which placed in 0○ and 90○ relative to the anode axis. Neutron scattering from two activation counters was calculated with MCNP4C code and the results showed that this effect is negligible. In this article, the probability of implanting deuterium ions into the titanium target was also investigated. Deviation angle of the ion emission relative to the anode axis was measured experimentally in this research and it was about 3.1○. Copyright © Cambridge University Press 2014.
Radiation Physics and Chemistry (18790895) 101pp. 59-65
This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6. mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5. mbar and 3.75. kJ stored energy. The results of x-ray dose from the device showed that about 0.6. mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8. mm in diameter and the cut-off frequency was obtained to be about 1.5. cycles/mm. © 2014 Elsevier Ltd.
Journal of Fusion Energy (15729591) 33(4)pp. 351-359
A new 20 kJ Filippov-type plasma focus device has been designed and constructed in Isfahan University. The paper reports on the design and construction of the Iranian Filippov-type plasma focus device (UIPFF1) using modified Lee's model. A Rogowski coil has been used to measure the experimental discharge current. Equivalent electric circuit of the device is RLC circuit; therefore the discharge current has a sinusoidal shape which its amplitude decreases exponentially during the time. The current signal contains a set of data from physical processes in the device as well as discharge current characteristics. In a typical discharge experiment these values were obtained: the discharge current was 181 kA, period of current signal 7.9 μs, the total inductance of the device 132 nH and electrical resistance of the circuit 77 m. By averaging from data obtained with a set of five experiments the calibration factor was obtained 121 kA/V. Temporal changes in plasma focus discharge current, confirmed the occurrence of pinch at a specific pressure of argon, neon and nitrogen gases. UIPFF1 has been tested between 15 and 25 kV and wide range of pressure for various gases. Experiments at various pressures and voltages have also confirmed reproducibility and stability of the plasma focus device. © 2014 Springer Science+Business Media New York.
Journal of Fusion Energy (15729591) 33(3)pp. 286-293
The state space of Lee's model (SSL model) is a model developed for plasma behavior in Filippov-type plasma focus facilities which has been described and used. This model is attractive because it provides a practical approach for analysis of a plasma focus device. In this article, we turn to an alternative method of system analysis using time-domain methods. We will reconsider the differential equations describing the Filippov-type plasma focus device and select a certain form of differential equations. We will use a set of variables that can be used to establish a set of first-order differential equations. Using matrix methods, we will be able to determine the transient response of the Filippov-type plasma focus device and examine the performance of this system. This model is a derivation of modified Lee's model and is based on the so-called slug model. Using the SSL model, the discharged current and its derivative as a function of time, pinch time, and maximum discharge current; as functions of pressure, have been predicted. The experimental data obtained by using the UIPFF1 facility with a maximum energy of 20 kJ is compared with the simulated data obtained through SSL model. This investigation shows that the SSL model is capable of predicting the plasma behavior in the Filippov type plasma focus. © 2014 Springer Science+Business Media New York.
Applied Radiation and Isotopes (09698043) 74pp. 86-90
This paper explores the production of 13N by bombardment of a carbon target by high energy deuterons in a medium energy plasma focus. A set of experiments in the energy range of 2.7-3.1kJ and initial pressure of 200-700Pa, with three or five shots in each experiment, was performed. A HPGe detector was used for gamma spectroscopy, and 511keV photons emitted by positron annihilation were utilized to measure the 13N radioactivity. The highest activity of 13N in these experiments was 14Bq which was acquired after five shots at a pressure of 450Pa and a 3.1kJ stored energy. Calculations based on thick target yield showed that at least 1.9×109 deuterons with energies higher than 330keV were ejected from the pinch region. © 2013 Elsevier Ltd.
Journal of Fusion Energy (15729591) 32(2)pp. 235-241
In this paper, the feasibility of 13N radioisotope production by a small plasma focus device for using in positron emission tomography (PET) has been studied. A large quantity of experimental data on the deuteron beam emission in dense plasma focuses are summarized and has been used in estimation of deuteron energy spectrum, intensity and angular distribution. The induced activity of 13N by 12C(d,n)13N reaction in an external solid target is calculated for different 'm' values (the power in energy distribution function of deuterons), and for a repetition rate plasma focus. A small plasma focus can produce 13N radionuclides in the order of 10 kBq in one shot, and it can be increased to few 10 MBq in a rep rate working mode with f = 10 Hz after 600 s operating time. Whereas a typical PET scan in myocardial blood perfusion assessment requires about 4 GBq radiopharmaceutical of 13N, it is concluded that a small plasma focus device, even with repetition frequency of f = 10 Hz can't produce adequate 13N activity for this special PET imaging. Nonetheless, higher producible activities in higher energy PF devices and by endogenous production methods (i.e.; nuclear reactions are induced inside the pinch itself) maybe result to introduction of an optimized repetitive high energy plasma focus as an alternative for cyclotrons in this special application. © 2012 Springer Science+Business Media, LLC.
Brazilian Journal Of Physics (01039733) 40(2)pp. 125-130
In this work, a 2.5kJ plasma focus device (named as SBUPF1) has been constructed on the basis of a simple configuration. The most important characteristics of this configuration is relative simplicity and using less components in its structure compared with common configurations. SBUPF1 has been tested between 18-25kV and wide range of pressure for various gases including Argon, Neon and Deuterium. The system shows consistent and reproducible plasma focusing action as well as fusion neutron production (when deuterium is used as working gas).
