Pub Date : 2009-05-19DOI: 10.1080/10519990902885248
M. Miyamoto, K. Ono, H. Urabe, T. Nakano, N. Yoshida
To evaluate the optical reflectivity deterioration of first mirrors for plasma diagnostics, in situ measurements of the laser reflectivity have been performed under the irradiation with low-energy helium ions in stainless steel, Mo and W. Surface morphology and radiation damage in sub-surface region have also been examined using scanning electron microscope, atomic force microscope and transmission electron microscope. It is found that the deterioration of the reflectivity under the irradiation with helium ions is very severe and depends on the ion energy, fluence and wavelength. Although fine roughness on the specimen surface was observed in irradiated materials, the size is too tiny to explain the present degradation of the reflectivity by using a Bennett's equation. On the other hand, from the present observation a strong correlation between the deterioration of the reflectivity and the formation of radiation damages in the surface and sub-surface regions of the laser penetration depth is suggested.
{"title":"Deterioration of the reflectivity in first-mirror materials under irradiation with low-energy helium ions","authors":"M. Miyamoto, K. Ono, H. Urabe, T. Nakano, N. Yoshida","doi":"10.1080/10519990902885248","DOIUrl":"https://doi.org/10.1080/10519990902885248","url":null,"abstract":"To evaluate the optical reflectivity deterioration of first mirrors for plasma diagnostics, in situ measurements of the laser reflectivity have been performed under the irradiation with low-energy helium ions in stainless steel, Mo and W. Surface morphology and radiation damage in sub-surface region have also been examined using scanning electron microscope, atomic force microscope and transmission electron microscope. It is found that the deterioration of the reflectivity under the irradiation with helium ions is very severe and depends on the ion energy, fluence and wavelength. Although fine roughness on the specimen surface was observed in irradiated materials, the size is too tiny to explain the present degradation of the reflectivity by using a Bennett's equation. On the other hand, from the present observation a strong correlation between the deterioration of the reflectivity and the formation of radiation damages in the surface and sub-surface regions of the laser penetration depth is suggested.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"4 1","pages":"155 - 164"},"PeriodicalIF":0.0,"publicationDate":"2009-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78815793","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 : 2009-05-19DOI: 10.1080/10519990902909436
A. Mase, Y. Kogi, N. Ito, Y. Yokota, K. Akaki, K. Kawahata, Y. Nagayama, T. Tokuzawa, S. Yamaguchi, H. Hojo, N. Oyama, N. Luhmann, H. Park, A. Donne
Microwave to millimeter-wave diagnostic techniques such as interferometry, reflectometry, scattering and radiometry have been powerful tools for diagnosing magnetically confined plasmas. Recent advances in electronic devices and components together with computer technology have enabled the development of advanced diagnostics in microwave to millimeter-wave region. The two-dimensional and three-dimensional profiles of plasma density/temperature and dynamic behaviors of their fluctuations are measured by using the advanced diagnostic systems. The measurements have clarified the physics issues such as stability, wave phenomena and fluctuation-induced transport. We report here on the representative microwave diagnostics and their contribution to plasma confinement physics.
{"title":"Advancements of microwave diagnostics in magnetically confined plasmas","authors":"A. Mase, Y. Kogi, N. Ito, Y. Yokota, K. Akaki, K. Kawahata, Y. Nagayama, T. Tokuzawa, S. Yamaguchi, H. Hojo, N. Oyama, N. Luhmann, H. Park, A. Donne","doi":"10.1080/10519990902909436","DOIUrl":"https://doi.org/10.1080/10519990902909436","url":null,"abstract":"Microwave to millimeter-wave diagnostic techniques such as interferometry, reflectometry, scattering and radiometry have been powerful tools for diagnosing magnetically confined plasmas. Recent advances in electronic devices and components together with computer technology have enabled the development of advanced diagnostics in microwave to millimeter-wave region. The two-dimensional and three-dimensional profiles of plasma density/temperature and dynamic behaviors of their fluctuations are measured by using the advanced diagnostic systems. The measurements have clarified the physics issues such as stability, wave phenomena and fluctuation-induced transport. We report here on the representative microwave diagnostics and their contribution to plasma confinement physics.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"102 1","pages":"116 - 98"},"PeriodicalIF":0.0,"publicationDate":"2009-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80272220","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 : 2009-05-19DOI: 10.1080/10519990902884522
T. Akiyama, K. Kawahata, S. Okajima, K. Nakayama
Measurement of an internal magnetic field distribution in magnetically confined fusion devices is indispensable for both understanding the plasma physics and controlling plasmas. A polari-interferometer based on the Faraday effect has been used for such a purpose. This paper describes performance evaluations of a part of the polarimeter with photoelastic modulators (PEMs) of the short-wavelength far-infrared (FIR) laser polari-interferometer. The wavelengths of the light source are 57.2 and 47.7 μ m, which are suitable for a high-density operation and large fusion devices. The PEM for the FIR region is newly developed with high-resistive silicon in which absorption of the FIR laser is small. The polarization angle is successfully measured and an angle resolution of 0.01° with a time resolution of 1 ms is achieved. A drift of the baseline of about 0.1° for 1000 s is observed and is found to be caused by changes in the room temperature.
{"title":"Performance evaluation of short-wavelength FIR laser polarimeter with dual silicon photoelastic modulators","authors":"T. Akiyama, K. Kawahata, S. Okajima, K. Nakayama","doi":"10.1080/10519990902884522","DOIUrl":"https://doi.org/10.1080/10519990902884522","url":null,"abstract":"Measurement of an internal magnetic field distribution in magnetically confined fusion devices is indispensable for both understanding the plasma physics and controlling plasmas. A polari-interferometer based on the Faraday effect has been used for such a purpose. This paper describes performance evaluations of a part of the polarimeter with photoelastic modulators (PEMs) of the short-wavelength far-infrared (FIR) laser polari-interferometer. The wavelengths of the light source are 57.2 and 47.7 μ m, which are suitable for a high-density operation and large fusion devices. The PEM for the FIR region is newly developed with high-resistive silicon in which absorption of the FIR laser is small. The polarization angle is successfully measured and an angle resolution of 0.01° with a time resolution of 1 ms is achieved. A drift of the baseline of about 0.1° for 1000 s is observed and is found to be caused by changes in the room temperature.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"45 1","pages":"117 - 125"},"PeriodicalIF":0.0,"publicationDate":"2009-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90069056","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 : 2009-02-20DOI: 10.1080/10519990802703277
I. Lyublinski, A. Vertkov, V. Evtikhin
A short analysis of lithium properties presented in this article was carried out in terms of lithium application in various systems of a fusion reactor. The article is intended for use by the engineers and researchers involved in activities on thermonuclear fusion.
{"title":"Application of lithium in systems of fusion reactors. 1. Physical and chemical properties of lithium","authors":"I. Lyublinski, A. Vertkov, V. Evtikhin","doi":"10.1080/10519990802703277","DOIUrl":"https://doi.org/10.1080/10519990802703277","url":null,"abstract":"A short analysis of lithium properties presented in this article was carried out in terms of lithium application in various systems of a fusion reactor. The article is intended for use by the engineers and researchers involved in activities on thermonuclear fusion.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"49 1","pages":"42 - 72"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89809131","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 : 2009-02-20DOI: 10.1080/10519990802703319
A. Zhukeshov
Distribution of energy density of a plasma flow in the KPU-30 pulse coaxial accelerator at continuous gas filling has been investigated. The influence of discharge parameters on energy density at various pressures of the working gas is demonstrated. It is shown that the maximal plasma energy occurs in a pressure range of 0.02–0.05 torr. Distributions of energy density in the axial and radial directions are obtained. The focus point of the plasma flow is found and the plasma flow energy density at this point is measured.
{"title":"Plasma flow formation in a pulse plasma accelerator in continuous filling regime","authors":"A. Zhukeshov","doi":"10.1080/10519990802703319","DOIUrl":"https://doi.org/10.1080/10519990802703319","url":null,"abstract":"Distribution of energy density of a plasma flow in the KPU-30 pulse coaxial accelerator at continuous gas filling has been investigated. The influence of discharge parameters on energy density at various pressures of the working gas is demonstrated. It is shown that the maximal plasma energy occurs in a pressure range of 0.02–0.05 torr. Distributions of energy density in the axial and radial directions are obtained. The focus point of the plasma flow is found and the plasma flow energy density at this point is measured.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"90 1","pages":"73 - 81"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77906713","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 : 2009-02-20DOI: 10.1080/10519990802696455
H. M. Soliman, T. Allam, S. Abd El-Latif
A cumulative phenomenon of nitrogen gas at a pressure of 3.3 torr in a 1.2 kJ coaxial plasma focus discharge device was investigated experimentally. Variations of nitrogen gas density in the axial phase along the inter-electrode region were estimated experimentally from the plasma current sheath (PCS) dynamics in terms of its velocity, acceleration as well as axial magnetic force data. An inclination angle of PCS with the axial distance was estimated. Investigations of the ratios of radial and axial magnetic force as well as the magnetic pressures coupled to PCS were studied. The variation of the trapping fraction η with the axial distance was computed theoretically based on a snow-plow model and was compared with experimental results.
{"title":"Study of a cumulative gas phenomenon in plasma focus discharge","authors":"H. M. Soliman, T. Allam, S. Abd El-Latif","doi":"10.1080/10519990802696455","DOIUrl":"https://doi.org/10.1080/10519990802696455","url":null,"abstract":"A cumulative phenomenon of nitrogen gas at a pressure of 3.3 torr in a 1.2 kJ coaxial plasma focus discharge device was investigated experimentally. Variations of nitrogen gas density in the axial phase along the inter-electrode region were estimated experimentally from the plasma current sheath (PCS) dynamics in terms of its velocity, acceleration as well as axial magnetic force data. An inclination angle of PCS with the axial distance was estimated. Investigations of the ratios of radial and axial magnetic force as well as the magnetic pressures coupled to PCS were studied. The variation of the trapping fraction η with the axial distance was computed theoretically based on a snow-plow model and was compared with experimental results.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"58 1","pages":"32 - 41"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73785770","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 : 2009-02-20DOI: 10.1080/10519990802646104
R. Amrollahi, M. Habibi, S. Shahshenas
In this paper, we study the effect of current sheath symmetry on pinched plasma intensity in Amirkabir Plasma Focus (APF) facility (16 kV, 36 μ f and 115 nH) by the magnetic probes. The arrival times of current sheath reaching to the probes, the signals of hard X-ray (HXR) and also discharge current signal are recorded simultaneously. The simulated trajectory, velocity and intensity of current sheath are compared with the experimental results. There seems to be a good accordance among current sheath symmetry, pinched plasma intensity and HXR yield.
{"title":"Correlation between plasma pinch intensity, current sheath symmetry, and HXR yield by APF plasma focus device","authors":"R. Amrollahi, M. Habibi, S. Shahshenas","doi":"10.1080/10519990802646104","DOIUrl":"https://doi.org/10.1080/10519990802646104","url":null,"abstract":"In this paper, we study the effect of current sheath symmetry on pinched plasma intensity in Amirkabir Plasma Focus (APF) facility (16 kV, 36 μ f and 115 nH) by the magnetic probes. The arrival times of current sheath reaching to the probes, the signals of hard X-ray (HXR) and also discharge current signal are recorded simultaneously. The simulated trajectory, velocity and intensity of current sheath are compared with the experimental results. There seems to be a good accordance among current sheath symmetry, pinched plasma intensity and HXR yield.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"27 1","pages":"1 - 7"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72909985","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 : 2009-02-20DOI: 10.1080/10519990802677679
A. Essiptchouk, L. Sharakhovsky, A. Marotta
Current–voltage characteristics (CVCs) of a transferred arc in a limited volume are reported. Experiments were carried out with a setup developed to reproduce the conditions which occur in a tundish equipped with a plasma system to keep the steel temperature at a predefined level. The experimental setup consists of a test chamber in which a plasma torch with a transferred arc is inserted on the top of the chamber cover and the anode is attached at the bottom. A ‘hysteresis’ of the CVC curves was observed during an increase and a decrease in the arc current. This phenomenon is explained by a long-lived ring-shaped vortex flow in the chamber, which is powered by the forces that at high currents act as an electromagnetic pump accelerating plasma in the direction of current expansion.
{"title":"Peculiarity of current–voltage characteristics of transferred arc burning in a limited volume","authors":"A. Essiptchouk, L. Sharakhovsky, A. Marotta","doi":"10.1080/10519990802677679","DOIUrl":"https://doi.org/10.1080/10519990802677679","url":null,"abstract":"Current–voltage characteristics (CVCs) of a transferred arc in a limited volume are reported. Experiments were carried out with a setup developed to reproduce the conditions which occur in a tundish equipped with a plasma system to keep the steel temperature at a predefined level. The experimental setup consists of a test chamber in which a plasma torch with a transferred arc is inserted on the top of the chamber cover and the anode is attached at the bottom. A ‘hysteresis’ of the CVC curves was observed during an increase and a decrease in the arc current. This phenomenon is explained by a long-lived ring-shaped vortex flow in the chamber, which is powered by the forces that at high currents act as an electromagnetic pump accelerating plasma in the direction of current expansion.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"89 1","pages":"23 - 31"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84260080","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 : 2009-02-20DOI: 10.1080/10519990802646096
Y. Ding, G. Zhuang, X. Q. Zhang, W. Ba, M. Zhang, J. Yao, W. J. Wang, Y. Pan
Compared with the conventional Rogowski coils made by winding wire loops, a printed circuit board (PCB) based on Rogowski coils has some favourable advantages for current measurements, such as large effective area, good linearity, high frequency response, precise geometry and thin profile. This type of Rogowski coil has been widely applied in electrical systems as the current sensor. Nevertheless, the PCB Rogowski coils are introduced for the first time to measure the plasma current on the Joint Texas Experimental Tokamak (J-TEXT). The measurements have shown that this novel PCB Rogowski coil works perfectly and is very suitable for studies of disruption, equilibrium reconstruction, etc.
{"title":"The printed circuit board Rogowski coils for plasma current measurements on the J-TEXT tokamak","authors":"Y. Ding, G. Zhuang, X. Q. Zhang, W. Ba, M. Zhang, J. Yao, W. J. Wang, Y. Pan","doi":"10.1080/10519990802646096","DOIUrl":"https://doi.org/10.1080/10519990802646096","url":null,"abstract":"Compared with the conventional Rogowski coils made by winding wire loops, a printed circuit board (PCB) based on Rogowski coils has some favourable advantages for current measurements, such as large effective area, good linearity, high frequency response, precise geometry and thin profile. This type of Rogowski coil has been widely applied in electrical systems as the current sensor. Nevertheless, the PCB Rogowski coils are introduced for the first time to measure the plasma current on the Joint Texas Experimental Tokamak (J-TEXT). The measurements have shown that this novel PCB Rogowski coil works perfectly and is very suitable for studies of disruption, equilibrium reconstruction, etc.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"83 1","pages":"15 - 8"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90295981","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 : 2009-02-20DOI: 10.1080/10519990802703434
Q. Zou, Mingzhi Wang, A. Hatta
Electron field emission (FE) from carbon nanotubes (CNTs) in atmospheric pressure Ar gas was measured. The FE measurements were carried out using a needle for anode and a CNT specimen for cathode. The FE current usually appeared at several hundred volts at applied voltage to the anode at the gap length from 15 to 100 μm. When the applied voltage was lower than a conventional gas breakdown voltage around 300 V, the FE in Ar gas was stable and reproducible even at atmospheric pressure. There was no damage on the surface of CNT cathode in SEM observation after the FE operation in Ar gas. When the applied voltage was increased to more than the gas breakdown voltage, a conventional gas discharge took place resulting in destroying the CNT cathode surface.
{"title":"Electron field emission from carbon nanotubes in atmospheric pressure Ar gas","authors":"Q. Zou, Mingzhi Wang, A. Hatta","doi":"10.1080/10519990802703434","DOIUrl":"https://doi.org/10.1080/10519990802703434","url":null,"abstract":"Electron field emission (FE) from carbon nanotubes (CNTs) in atmospheric pressure Ar gas was measured. The FE measurements were carried out using a needle for anode and a CNT specimen for cathode. The FE current usually appeared at several hundred volts at applied voltage to the anode at the gap length from 15 to 100 μm. When the applied voltage was lower than a conventional gas breakdown voltage around 300 V, the FE in Ar gas was stable and reproducible even at atmospheric pressure. There was no damage on the surface of CNT cathode in SEM observation after the FE operation in Ar gas. When the applied voltage was increased to more than the gas breakdown voltage, a conventional gas discharge took place resulting in destroying the CNT cathode surface.","PeriodicalId":54600,"journal":{"name":"Plasma Devices and Operations","volume":"18 1","pages":"82 - 87"},"PeriodicalIF":0.0,"publicationDate":"2009-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89768833","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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