Pub Date : 2007-07-19DOI: 10.1080/10519990701458593
A. Sintsov, E. Kryuchkov, V. Apse, A. Shmelev
The paper evaluates the capability of fusion facilities to produce fissionable materials with the maximum content of the artificial isotopes 237Np and 231Pa. In particular, the paper investigates the effects of the 237Np or 231Pa production zone thickness and the composition of the next zone on the production rates of fissionable isotopes under neutron irradiation of 238U or 232Th. It is demonstrated that relatively thin (about 10 cm thick) uranium or thorium zones should be applied for the production of 237Np and 231Pa. Also, it is revealed that incorporation of 237Np or 231Pa production zones into the blanket module of an International Thermonuclear Experimental Reactor type of fusion facility leads to reduced attenuation of the fast-neutron flux by the blanket module.
{"title":"Fusion neutron source: potential in the production of 237Np and 231Pa for improving the proliferation protection of nuclear materials","authors":"A. Sintsov, E. Kryuchkov, V. Apse, A. Shmelev","doi":"10.1080/10519990701458593","DOIUrl":"https://doi.org/10.1080/10519990701458593","url":null,"abstract":"The paper evaluates the capability of fusion facilities to produce fissionable materials with the maximum content of the artificial isotopes 237Np and 231Pa. In particular, the paper investigates the effects of the 237Np or 231Pa production zone thickness and the composition of the next zone on the production rates of fissionable isotopes under neutron irradiation of 238U or 232Th. It is demonstrated that relatively thin (about 10 cm thick) uranium or thorium zones should be applied for the production of 237Np and 231Pa. Also, it is revealed that incorporation of 237Np or 231Pa production zones into the blanket module of an International Thermonuclear Experimental Reactor type of fusion facility leads to reduced attenuation of the fast-neutron flux by the blanket module.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"9 1","pages":"163 - 184"},"PeriodicalIF":0.0,"publicationDate":"2007-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87124607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990601125151
A. Qayyum, Shaista Zeb, M. Naveed, S. A. Ghauri, M. Zakaullah
Trace-rare-gas optical actinometry is used to measure the N-atom density in 50 Hz pulsed dc nitrogen plasma as functions of the discharge parameters. The excited-state population density of N atoms is extracted from their respective optical transitions and is related to the ground-state population density by considering the changes in the electron energy distribution function. This technique provides reliable information on the atomic N concentration in the gas discharge, which is vital in the synthesis of nitrides owing to its high chemical reactivity.
{"title":"Optical actinometry of the N-atom density in nitrogen plasma","authors":"A. Qayyum, Shaista Zeb, M. Naveed, S. A. Ghauri, M. Zakaullah","doi":"10.1080/10519990601125151","DOIUrl":"https://doi.org/10.1080/10519990601125151","url":null,"abstract":"Trace-rare-gas optical actinometry is used to measure the N-atom density in 50 Hz pulsed dc nitrogen plasma as functions of the discharge parameters. The excited-state population density of N atoms is extracted from their respective optical transitions and is related to the ground-state population density by considering the changes in the electron energy distribution function. This technique provides reliable information on the atomic N concentration in the gas discharge, which is vital in the synthesis of nitrides owing to its high chemical reactivity.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"39 1","pages":"87 - 93"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73552184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990701211398
Y. Gott
With the help of the standard neoclassical formalism, the particle guiding-centre distribution function in tokamaks is derived, taking into account the effect of magnetic field gradients. It is shown that the radial gradient of the parallel velocity, which depends on the magnetic field strength gradient, produces a parallel current additive to the conventional neoclassical bootstrap current. The existence of the parallel current on the magnetic axis may reduce or eliminate the need for a seed current in a tokamak reactor. The radial gradient of magnetic field also produces thermal and particle pinches. The thermal pinch significantly decreases the net heat flux in the vicinity of the magnetic axis, and this result is found to be in agreement with experimental trends. The particle pinch can play an important role in impurity transport.
{"title":"The charged-particle distribution function in tokamaks modified by a magnetic field gradient","authors":"Y. Gott","doi":"10.1080/10519990701211398","DOIUrl":"https://doi.org/10.1080/10519990701211398","url":null,"abstract":"With the help of the standard neoclassical formalism, the particle guiding-centre distribution function in tokamaks is derived, taking into account the effect of magnetic field gradients. It is shown that the radial gradient of the parallel velocity, which depends on the magnetic field strength gradient, produces a parallel current additive to the conventional neoclassical bootstrap current. The existence of the parallel current on the magnetic axis may reduce or eliminate the need for a seed current in a tokamak reactor. The radial gradient of magnetic field also produces thermal and particle pinches. The thermal pinch significantly decreases the net heat flux in the vicinity of the magnetic axis, and this result is found to be in agreement with experimental trends. The particle pinch can play an important role in impurity transport.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"19 1","pages":"105 - 95"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81529211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990601109049
S. Bendella, A. Belasri
We have used a one-dimensional model of the cathode sheath with an external circuit coupled to a kinetics model of the plasma. With a very high potential and a very high pressure, multiplication of the initial electrons due to ionization during their transits towards the anode causes much positive space charge which distorts the distribution of the electric field. The ions thus created in the volume by the initial electrons turn towards the cathode, causing the emission of secondary electrons and consequently producing more avalanches. Breakdown is primarily due to successive avalanches of the electrons of the cathode which are propagated in the sheath with a high field. Plasma is thus formed; ionization is mainly due to the electron impact but is also due to accumulation of the metastable species in the gap. The growth of the excited-state Xe* is caused by the electron impact of the xenon atoms and NeXe+ ions.
{"title":"Xe–Ne–HCl excimer lamp excited by a phototriggered discharge","authors":"S. Bendella, A. Belasri","doi":"10.1080/10519990601109049","DOIUrl":"https://doi.org/10.1080/10519990601109049","url":null,"abstract":"We have used a one-dimensional model of the cathode sheath with an external circuit coupled to a kinetics model of the plasma. With a very high potential and a very high pressure, multiplication of the initial electrons due to ionization during their transits towards the anode causes much positive space charge which distorts the distribution of the electric field. The ions thus created in the volume by the initial electrons turn towards the cathode, causing the emission of secondary electrons and consequently producing more avalanches. Breakdown is primarily due to successive avalanches of the electrons of the cathode which are propagated in the sheath with a high field. Plasma is thus formed; ionization is mainly due to the electron impact but is also due to accumulation of the metastable species in the gap. The growth of the excited-state Xe* is caused by the electron impact of the xenon atoms and NeXe+ ions.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"6 1","pages":"77 - 85"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74349796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990701281235
D. Orlinski, V. Voitsenya, K. Vukolov
In part II of this review, the results of experiments on the exposure of mirrors in the operating fusion devices are described (we restricted the results to those that had been obtained up to the end of 2004). It is shown that in the locations that are suitable for the positions of the mirrors (at the ports and divertor), as well as near the carbon graphite limiters, the appearance of deposits predominates. However, there are also regions in the vacuum vessel where the main effect is mirror sputtering. In this connection, two methods of mirror cleaning that can possibly be used in situ are described: by a gas-discharge low-temperature plasma and by repeated laser shots. Also, the effect of multiple-shot laser illumination on the survivability of metallic mirrors of laser diagnostics is analysed.
{"title":"First mirrors for diagnostic systems of an experimental fusion reactor II. The mirror tests on the large fusion devices under operation","authors":"D. Orlinski, V. Voitsenya, K. Vukolov","doi":"10.1080/10519990701281235","DOIUrl":"https://doi.org/10.1080/10519990701281235","url":null,"abstract":"In part II of this review, the results of experiments on the exposure of mirrors in the operating fusion devices are described (we restricted the results to those that had been obtained up to the end of 2004). It is shown that in the locations that are suitable for the positions of the mirrors (at the ports and divertor), as well as near the carbon graphite limiters, the appearance of deposits predominates. However, there are also regions in the vacuum vessel where the main effect is mirror sputtering. In this connection, two methods of mirror cleaning that can possibly be used in situ are described: by a gas-discharge low-temperature plasma and by repeated laser shots. Also, the effect of multiple-shot laser illumination on the survivability of metallic mirrors of laser diagnostics is analysed.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"43 1","pages":"127 - 146"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81365385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990701322807
V. Burtsev, N. Kalinin
Numerical simulation of a radiating theta discharge pressed to the inner wall of a cylindrical dielectric chamber under the pressure of a trapped longitudinal magnetic field has been carried out in a high-pressure gas. The longitudinal magnetic field is created by a solenoid, which acts as inductive energy storage; an electro-explosive current breaker is used as an opening switch for this energy storage. It is shown that discharges of this type allow radial converging radiation fluxes of different spectral structures to be formed and the luminance temperature on the axis to vary in the range of several electronvolts.
{"title":"Self-pressed radiating theta discharge with trapped magnetic flux","authors":"V. Burtsev, N. Kalinin","doi":"10.1080/10519990701322807","DOIUrl":"https://doi.org/10.1080/10519990701322807","url":null,"abstract":"Numerical simulation of a radiating theta discharge pressed to the inner wall of a cylindrical dielectric chamber under the pressure of a trapped longitudinal magnetic field has been carried out in a high-pressure gas. The longitudinal magnetic field is created by a solenoid, which acts as inductive energy storage; an electro-explosive current breaker is used as an opening switch for this energy storage. It is shown that discharges of this type allow radial converging radiation fluxes of different spectral structures to be formed and the luminance temperature on the axis to vary in the range of several electronvolts.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"85 1","pages":"147 - 158"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78181908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990701195039
D. Yarmolich, Vladislav Vekselman, J. Gleizer, Y. Hadas, J. Felsteiner, Y. Krasik, V. Bernshtam
Thomson scattering and visible spectroscopy were applied to study the parameters of plasma formed in a hollow-anode discharge (about 1 kA) prior and during electron beam extraction (approximately 1 kA; 300 kV). The discharge was ignited and sustained by ferroelectric plasma sources incorporated in the hollow anode. It was found that during the hollow-anode operation the density and energy of the ferroelectric surface plasma electrons are about 1015 cm−3 and not more than 5 eV, respectively. The density and temperature of the bulk hollow anode plasma electrons were found to be about 6×1013 cm−3 and about 10 eV, respectively. During an acceleration pulse the surface plasma electron density and energy increased to approximately 6×1016 cm−3 and not more than 20 eV respectively, while the bulk plasma parameters remain unchanged. Also, it was shown that the plasma formation on the ferroelectric surface is accompanied by the generation of microparticles having velocities up to 3×105 cm s−1.
{"title":"Non-disturbing measurements of hollow-anode plasma parameters","authors":"D. Yarmolich, Vladislav Vekselman, J. Gleizer, Y. Hadas, J. Felsteiner, Y. Krasik, V. Bernshtam","doi":"10.1080/10519990701195039","DOIUrl":"https://doi.org/10.1080/10519990701195039","url":null,"abstract":"Thomson scattering and visible spectroscopy were applied to study the parameters of plasma formed in a hollow-anode discharge (about 1 kA) prior and during electron beam extraction (approximately 1 kA; 300 kV). The discharge was ignited and sustained by ferroelectric plasma sources incorporated in the hollow anode. It was found that during the hollow-anode operation the density and energy of the ferroelectric surface plasma electrons are about 1015 cm−3 and not more than 5 eV, respectively. The density and temperature of the bulk hollow anode plasma electrons were found to be about 6×1013 cm−3 and about 10 eV, respectively. During an acceleration pulse the surface plasma electron density and energy increased to approximately 6×1016 cm−3 and not more than 20 eV respectively, while the bulk plasma parameters remain unchanged. Also, it was shown that the plasma formation on the ferroelectric surface is accompanied by the generation of microparticles having velocities up to 3×105 cm s−1.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"10 1","pages":"115 - 125"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74892845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-04-11DOI: 10.1080/10519990701195054
Y. Krasik, S. Gleizer, P. Nozar, C. Taliani
We present the results for a channel spark discharge which show a substantial difference between the pressure in the experimental chamber and the pressure in the hollow cathode (HC). For the pressure range (1−8)×10−2 Torr measured in the experimental chamber, the pressure in the hollow cathode is changed in the range (8−16)×10−2 Torr. An analysis of the pressure data obtained by pumping of the experimental chamber via the HC showed that there are three modes of the system pumping, namely molecular, transient and viscous. Finally, it was shown that applying a discharge voltage with amplitude up to 50 keV allows electron beams to be generated with an efficiency up to 10%, a maximum electron energy spectrum at about 25 keV and a current amplitude of several hundred amperes.
{"title":"Pressure and electron energy measurements in a channel spark discharge","authors":"Y. Krasik, S. Gleizer, P. Nozar, C. Taliani","doi":"10.1080/10519990701195054","DOIUrl":"https://doi.org/10.1080/10519990701195054","url":null,"abstract":"We present the results for a channel spark discharge which show a substantial difference between the pressure in the experimental chamber and the pressure in the hollow cathode (HC). For the pressure range (1−8)×10−2 Torr measured in the experimental chamber, the pressure in the hollow cathode is changed in the range (8−16)×10−2 Torr. An analysis of the pressure data obtained by pumping of the experimental chamber via the HC showed that there are three modes of the system pumping, namely molecular, transient and viscous. Finally, it was shown that applying a discharge voltage with amplitude up to 50 keV allows electron beams to be generated with an efficiency up to 10%, a maximum electron energy spectrum at about 25 keV and a current amplitude of several hundred amperes.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"37 1","pages":"107 - 114"},"PeriodicalIF":0.0,"publicationDate":"2007-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89931843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-03-01DOI: 10.1080/10519990601063634
P. Veronesi, C. Leonelli, G. Poli, M. Garuti
The aim of the work is to design a new compact microwave plasma source with a homogeneous circumferential distribution of the electric field intensity. The software for electromagnetic field simulation combined with design-of-experiments techniques was used to design and optimize the source geometry in terms of energy efficiency and field homogeneity. The basic assumption is that plasma can be described by an equivalent dielectric load. Two relatively simple microwave waveguide plasma sources have been simulated to study the effect of impedance-matching devices on the energy efficiency of the whole system. A microwave waveguide plasma source based on the WR340 waveguide geometry has been assembled to validate the model experimentally. A completely new compact plasma source, which is a toroidal waveguide and an innovative ‘self-adapting’ coupling slot, has been numerically simulated, designed and built. Preliminary tests confirmed the existence of a sufficiently homogeneous five-lobe distribution of the electric field.
{"title":"The design and optimization of a new microwave plasma source by numerical simulation","authors":"P. Veronesi, C. Leonelli, G. Poli, M. Garuti","doi":"10.1080/10519990601063634","DOIUrl":"https://doi.org/10.1080/10519990601063634","url":null,"abstract":"The aim of the work is to design a new compact microwave plasma source with a homogeneous circumferential distribution of the electric field intensity. The software for electromagnetic field simulation combined with design-of-experiments techniques was used to design and optimize the source geometry in terms of energy efficiency and field homogeneity. The basic assumption is that plasma can be described by an equivalent dielectric load. Two relatively simple microwave waveguide plasma sources have been simulated to study the effect of impedance-matching devices on the energy efficiency of the whole system. A microwave waveguide plasma source based on the WR340 waveguide geometry has been assembled to validate the model experimentally. A completely new compact plasma source, which is a toroidal waveguide and an innovative ‘self-adapting’ coupling slot, has been numerically simulated, designed and built. Preliminary tests confirmed the existence of a sufficiently homogeneous five-lobe distribution of the electric field.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"9 1","pages":"13 - 26"},"PeriodicalIF":0.0,"publicationDate":"2007-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80964976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-03-01DOI: 10.1080/10519990601160075
D. Orlinski, V. Voitsenya, K. Vukolov
Among the diagnostic systems planned for use in the International Thermonuclear Experimental Reactor to control the reactor operation, a large number of these systems have to use the mirrors to input or output the electromagnetic radiation to or from the burning plasma in different parts of the spectrum. The mirrors placed inside the vacuum vessel will be subjected to the impact of several factors, resulting in degradation in their optical characteristics. The most critical factors are erosion under the bombardment with a flux of high-energy particles, deuterons and tritons, and the deposition of the products of erosion of the in-vessel components. The first part of this review presents the results of the simulation experiments studying the effect of sputtering and deposition of contaminants on the optical properties of mirrors fabricated from different materials. In the second part of the review, the results of mirror testing on the operating large-scale fusion devices are considered.
{"title":"First mirrors for diagnostic systems of an experimental fusion reactor I. Simulation mirror tests under neutron and ion bombardment","authors":"D. Orlinski, V. Voitsenya, K. Vukolov","doi":"10.1080/10519990601160075","DOIUrl":"https://doi.org/10.1080/10519990601160075","url":null,"abstract":"Among the diagnostic systems planned for use in the International Thermonuclear Experimental Reactor to control the reactor operation, a large number of these systems have to use the mirrors to input or output the electromagnetic radiation to or from the burning plasma in different parts of the spectrum. The mirrors placed inside the vacuum vessel will be subjected to the impact of several factors, resulting in degradation in their optical characteristics. The most critical factors are erosion under the bombardment with a flux of high-energy particles, deuterons and tritons, and the deposition of the products of erosion of the in-vessel components. The first part of this review presents the results of the simulation experiments studying the effect of sputtering and deposition of contaminants on the optical properties of mirrors fabricated from different materials. In the second part of the review, the results of mirror testing on the operating large-scale fusion devices are considered.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"40 1","pages":"33 - 75"},"PeriodicalIF":0.0,"publicationDate":"2007-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81567789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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