Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4590953
A. Beunas, F. Kazarian
On TORE SUPRA (TS) located in Cadarache, the Lower Hybrid Current Drive (LHCD) 3.7 GHz system is being upgraded* in the frame of the CIMES project. Since the end of 2001, several technological components have been under manufacturing or have been installed. Particularly, a new high power CW klystron has been successfully developed and tested at Thales Electron Devices (TED) for CEA Cadarache. The main required performances are to deliver at 3.7 GHz, 700kW minimum output power on a matched load with a 44% efficiency, and 620kW minimum output power on a 1.4:1 VSWR all phases with a 38% efficiency, this latter case corresponding to the shot mode on plasma. The klystron has been factory tested up to 700 kW in CW operation on a matched load, without any difficulty. This operating point has been achieved at 73.1 kV and 20.7 A, with an efficiency of 47% and a gain of 52 dB. Power variation is less than 0.15 dB over the specified 5 MHz bandwidth. No instabilities were observed during tests. The power dissipated in the two klystron body cooling circuits is about 16.5 kW. The overall RF losses are estimated at 15 kW, which means that the beam losses are quite low, at 1.5 kW to be compared to the 1500 kW beam power. As a result, the temperatures of the output cavity noses are kept below 110 degC at 700 kW. Ten 1000s 700 kW shots were applied to the klystron with remarkably stable thermal and RF performances. On a mismatched load (1.4:1 VSWR), the tube has delivered 620 kW min, any phase, with an efficiency of 40%. As expected, a slight temperature rise of the output cavity noses (about 20degC) was observed, when compared to operation on a matched load at the same output power. In the diode mode, at full beam power, the measured temperatures of the collector inner wall are lower than 220degC. These results demonstrate that this new 3.7 GHz 700kW CW klystron has been designed with large thermal safely margins, which will ensure high operational reliability on the TORE SUPRA facility, but also good manufacturing yield during the serial production recently started at TED.
{"title":"High power CW klystrons for fusion experiments","authors":"A. Beunas, F. Kazarian","doi":"10.1109/PLASMA.2008.4590953","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590953","url":null,"abstract":"On TORE SUPRA (TS) located in Cadarache, the Lower Hybrid Current Drive (LHCD) 3.7 GHz system is being upgraded* in the frame of the CIMES project. Since the end of 2001, several technological components have been under manufacturing or have been installed. Particularly, a new high power CW klystron has been successfully developed and tested at Thales Electron Devices (TED) for CEA Cadarache. The main required performances are to deliver at 3.7 GHz, 700kW minimum output power on a matched load with a 44% efficiency, and 620kW minimum output power on a 1.4:1 VSWR all phases with a 38% efficiency, this latter case corresponding to the shot mode on plasma. The klystron has been factory tested up to 700 kW in CW operation on a matched load, without any difficulty. This operating point has been achieved at 73.1 kV and 20.7 A, with an efficiency of 47% and a gain of 52 dB. Power variation is less than 0.15 dB over the specified 5 MHz bandwidth. No instabilities were observed during tests. The power dissipated in the two klystron body cooling circuits is about 16.5 kW. The overall RF losses are estimated at 15 kW, which means that the beam losses are quite low, at 1.5 kW to be compared to the 1500 kW beam power. As a result, the temperatures of the output cavity noses are kept below 110 degC at 700 kW. Ten 1000s 700 kW shots were applied to the klystron with remarkably stable thermal and RF performances. On a mismatched load (1.4:1 VSWR), the tube has delivered 620 kW min, any phase, with an efficiency of 40%. As expected, a slight temperature rise of the output cavity noses (about 20degC) was observed, when compared to operation on a matched load at the same output power. In the diode mode, at full beam power, the measured temperatures of the collector inner wall are lower than 220degC. These results demonstrate that this new 3.7 GHz 700kW CW klystron has been designed with large thermal safely margins, which will ensure high operational reliability on the TORE SUPRA facility, but also good manufacturing yield during the serial production recently started at TED.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85043558","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590642
M. Gilmore, L. Yan, S. Xie, C. Watts, A. Lynn
Laboratory experiments are described which utilize a set of concentric bias rings to affect the velocity (flow) shear in the linear HELCAT (HELicon-CAThode) device at the University of New Mexico. HELCAT is 4 m long, 0.5 in diameter, with B0 les 2.2 kG, and utilizes two plasma sources: an RE helicon at one end of the device, and a thermionic cathode at the other. With increasing ring bias, relative to the vacuum chamber wall, it is found that both axial and azimuthal flow shear change by only a small amount in magnitude, but move inward to the plasma core from the wall. As bias is increased, drift waves decrease in magnitude and are eventually fully suppressed, then the Kelvin-Helmholtz (K-H) mode is destabilized. It appears that the azimuthal flow shear is mainly responsible for suppression of drift modes, while the azimuthal shear is the primary driver of the K-H instability. While bias applied to rings at any radii suppresses drift fluctuations with nearly equal effectiveness, the K-H mode is more easily excited by biasing at the plasma edge. Fluctuations show increasingly chaotic and intermittent behavior as bias increases, up to V ~ 10 kTe/e, when the chaos disappears, as indicated by a rapid drop in correlation dimension, and very bursty behavior. Additionally, detached edge "blobs" are observed in cathode plasmas, but appear to be absent from helicon discharges, even when other operating parameters (magnetic field, background pressure) are identical. Experimental results and comparisons with theory are described.
{"title":"Nonlinear dynamics of fluctuations in the presence of sheared parallel and perpendicular flows in a magnetized laboratory plasma","authors":"M. Gilmore, L. Yan, S. Xie, C. Watts, A. Lynn","doi":"10.1109/PLASMA.2008.4590642","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590642","url":null,"abstract":"Laboratory experiments are described which utilize a set of concentric bias rings to affect the velocity (flow) shear in the linear HELCAT (HELicon-CAThode) device at the University of New Mexico. HELCAT is 4 m long, 0.5 in diameter, with B0 les 2.2 kG, and utilizes two plasma sources: an RE helicon at one end of the device, and a thermionic cathode at the other. With increasing ring bias, relative to the vacuum chamber wall, it is found that both axial and azimuthal flow shear change by only a small amount in magnitude, but move inward to the plasma core from the wall. As bias is increased, drift waves decrease in magnitude and are eventually fully suppressed, then the Kelvin-Helmholtz (K-H) mode is destabilized. It appears that the azimuthal flow shear is mainly responsible for suppression of drift modes, while the azimuthal shear is the primary driver of the K-H instability. While bias applied to rings at any radii suppresses drift fluctuations with nearly equal effectiveness, the K-H mode is more easily excited by biasing at the plasma edge. Fluctuations show increasingly chaotic and intermittent behavior as bias increases, up to V ~ 10 kTe/e, when the chaos disappears, as indicated by a rapid drop in correlation dimension, and very bursty behavior. Additionally, detached edge \"blobs\" are observed in cathode plasmas, but appear to be absent from helicon discharges, even when other operating parameters (magnetic field, background pressure) are identical. Experimental results and comparisons with theory are described.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82086597","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590791
D. Welch, N. Bruner, D. Rose, K. Hahn, B. Oliver
Paraxial electron diodes with gas transport cells have been used to focus intense electron beams onto a high-Z target producing bremsstrahlung radiation. This configuration is being fielded on the recently commissioned RITS-6 accelerator producing 35-kA current and 10-MeV energy electron beams. Direct ionization of the beam and avalanche from the electron secondaries drive a break down of the gas that rapidly increases the gas cell conductivity. Non-ideal effects result in an axial sweep of the beam focus position that ultimately limits the radiographic spot. These effects include cathode plasma evolution, stimulated emission of anode ions, and magnetic diffusion in the gas cell. The gas breakdown is studied with hybrid particle-in-cell simulations using several different gas chemistry models including kinetic Monte Carlo interaction. In addition, we test the validity of these models against measured time- dependent beam spot and radiation production rates.
{"title":"Nonideal effects in the operation of a paraxial diode with gas cell focusing","authors":"D. Welch, N. Bruner, D. Rose, K. Hahn, B. Oliver","doi":"10.1109/PLASMA.2008.4590791","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590791","url":null,"abstract":"Paraxial electron diodes with gas transport cells have been used to focus intense electron beams onto a high-Z target producing bremsstrahlung radiation. This configuration is being fielded on the recently commissioned RITS-6 accelerator producing 35-kA current and 10-MeV energy electron beams. Direct ionization of the beam and avalanche from the electron secondaries drive a break down of the gas that rapidly increases the gas cell conductivity. Non-ideal effects result in an axial sweep of the beam focus position that ultimately limits the radiographic spot. These effects include cathode plasma evolution, stimulated emission of anode ions, and magnetic diffusion in the gas cell. The gas breakdown is studied with hybrid particle-in-cell simulations using several different gas chemistry models including kinetic Monte Carlo interaction. In addition, we test the validity of these models against measured time- dependent beam spot and radiation production rates.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79723945","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590820
N. Parsi, S. Gyawali, N. Boriraksantikul, P. Kirawanich, N. Islam, M. Pathan, D. Sleper
Summary form only given. Improvements in plant quality, root strength and seed germination through different means has been the subject of research for many. For example, low intensity and extreme low frequency magnetic field on sunflower and wheat seeds germination have produced positive effect. In this study different variety of soybean seeds have been exposed to electromagnetic and magnetic fields using an anechoic chamber and Helmholtz's Coil. The objective was to determine changes in the germination rate, if any, as a function of frequency, field intensity and duration of exposure. Soybean was chosen because, compared to other bio-fuel resources, it produces the maximum energy per gram and any increase in germination due to EM or magnetic field exposure would result in a greater production of this important asset. Experiments were conducted with four different varieties of soybean seeds namely Magellan, Maverick, SS97-6946 and Williams82. Results show that at 128 Watts, 100 MHz frequency and with exposure time of 10 minutes, only one variety of soybeans (Magellan) had a seven percent increase in the germination rate and was statistically significant. With an increase in the number of seeds per batch, the percent increase of germination for Magellan got down to five while for the other three types there was no change. There was statistical significance for germination of Magellan even for this experiment. Experiments were also conducted with the seeds in magnetic field of strengths 1G 5G and 10 G and exposure durations of 1 min, 5 min, 10 min and 20 min. Positive effect with 5 and 10 G field strength is reported. The number of seeds used in the magnetic field experiments was 25 and germination rate increase was again seen in the Magellan variety. This was further analyzed through statistical analysis which showed that for 5 G and 10 G field strengths the germination rate was significant.
{"title":"Improving germination rate of soybeans as a biofuel resource","authors":"N. Parsi, S. Gyawali, N. Boriraksantikul, P. Kirawanich, N. Islam, M. Pathan, D. Sleper","doi":"10.1109/PLASMA.2008.4590820","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590820","url":null,"abstract":"Summary form only given. Improvements in plant quality, root strength and seed germination through different means has been the subject of research for many. For example, low intensity and extreme low frequency magnetic field on sunflower and wheat seeds germination have produced positive effect. In this study different variety of soybean seeds have been exposed to electromagnetic and magnetic fields using an anechoic chamber and Helmholtz's Coil. The objective was to determine changes in the germination rate, if any, as a function of frequency, field intensity and duration of exposure. Soybean was chosen because, compared to other bio-fuel resources, it produces the maximum energy per gram and any increase in germination due to EM or magnetic field exposure would result in a greater production of this important asset. Experiments were conducted with four different varieties of soybean seeds namely Magellan, Maverick, SS97-6946 and Williams82. Results show that at 128 Watts, 100 MHz frequency and with exposure time of 10 minutes, only one variety of soybeans (Magellan) had a seven percent increase in the germination rate and was statistically significant. With an increase in the number of seeds per batch, the percent increase of germination for Magellan got down to five while for the other three types there was no change. There was statistical significance for germination of Magellan even for this experiment. Experiments were also conducted with the seeds in magnetic field of strengths 1G 5G and 10 G and exposure durations of 1 min, 5 min, 10 min and 20 min. Positive effect with 5 and 10 G field strength is reported. The number of seeds used in the magnetic field experiments was 25 and germination rate increase was again seen in the Magellan variety. This was further analyzed through statistical analysis which showed that for 5 G and 10 G field strengths the germination rate was significant.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79813534","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590704
S. Hassan, E. Clark, A. Gopal, S. Minardi, C. Petridis, J. Chatzakis, G. Androulakis, M. Tatarakis, E. Baronova, V. Vikhrev, P. Lee
We present the results from low current X-pinch machine capable to produce the current around 50 kA with a rise time of 50 ns. The X-pinches were made from two 5-10 mum diameter wires. The emission of EUV radiation at 13.5 nm starts from less than 10 ns time corresponding to the current flow in the wires and lasts about 100 ns. Details of dynamics of the pinch were obtained from laser shadowgraphic and time integrated images, showing formation and evolution of low density coronal plasma. The emission of EUV becomes twice in amplitude at the time of pinching within few nanoseconds rise-time. The multiple peaked structure observed in time resolved EUV and x-rays signals show the pinching and the formation of hotspots between 40 - 70 ns after the start of the current, depending on the diameter of the wires. The dynamics of the low current X-pinch in the radial as well as in the axial direction were simulated using the 2D MHD code.
{"title":"Compact low current X-pinch based EUV source for lithography","authors":"S. Hassan, E. Clark, A. Gopal, S. Minardi, C. Petridis, J. Chatzakis, G. Androulakis, M. Tatarakis, E. Baronova, V. Vikhrev, P. Lee","doi":"10.1109/PLASMA.2008.4590704","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590704","url":null,"abstract":"We present the results from low current X-pinch machine capable to produce the current around 50 kA with a rise time of 50 ns. The X-pinches were made from two 5-10 mum diameter wires. The emission of EUV radiation at 13.5 nm starts from less than 10 ns time corresponding to the current flow in the wires and lasts about 100 ns. Details of dynamics of the pinch were obtained from laser shadowgraphic and time integrated images, showing formation and evolution of low density coronal plasma. The emission of EUV becomes twice in amplitude at the time of pinching within few nanoseconds rise-time. The multiple peaked structure observed in time resolved EUV and x-rays signals show the pinching and the formation of hotspots between 40 - 70 ns after the start of the current, depending on the diameter of the wires. The dynamics of the low current X-pinch in the radial as well as in the axial direction were simulated using the 2D MHD code.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81790369","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590995
T. Gill, N. S. Saini, R. Mahajan
The growth of a radially symmetric ripple superimposed on a single intense Gaussian laser beam in a collisionless magnetized plasma is investigated. WKB and Paraxial ray approximations are used to calculate wave equation for the main beam and the ripple. Numerical results show that the relativistic power of laser beam, the dynamics of ripple gets affected by its position and phase angle as well as some other parameters. The effect of growth of ripple on excitation of upper hybrid wave is also studied.
{"title":"Growth of high power laser ripple in plasma and its effects on upper hybrid wave excitation: Relativistic effects","authors":"T. Gill, N. S. Saini, R. Mahajan","doi":"10.1109/PLASMA.2008.4590995","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590995","url":null,"abstract":"The growth of a radially symmetric ripple superimposed on a single intense Gaussian laser beam in a collisionless magnetized plasma is investigated. WKB and Paraxial ray approximations are used to calculate wave equation for the main beam and the ripple. Numerical results show that the relativistic power of laser beam, the dynamics of ripple gets affected by its position and phase angle as well as some other parameters. The effect of growth of ripple on excitation of upper hybrid wave is also studied.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80193970","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4591189
O. Kovalchuk, V. O. Kutenkov, I. Romanchenko, V. Rostov
In this paper, Ni-Zn ferrite loaded coaxial line, using oil as insulation, with subnanosecond rise time at the input pulse voltage up to 360 kV into a 50 load is described. The dependence of the shock front development on the line length and pulse voltage was investigated. The experimental data were compared with analytical predictions of early theory. The experimental and expected results are shown to be in quite good agreement. A modified ferrite-loaded line with lower impedance was fabricated in order to increase its magnetic field. The ferrite loaded line showed stable work at pulse repetition frequency of 100 Hz and the shortest rise time of 0.7 ns has been achieved. Benson et al have proposed to use an axial magnetic field bias for further pulse sharpening. Magnetic bias conditions for the optimal pulse sharpening were tested.
{"title":"Subnanosecond rise time of high voltage pulses in ferrite loaded coaxial line","authors":"O. Kovalchuk, V. O. Kutenkov, I. Romanchenko, V. Rostov","doi":"10.1109/PLASMA.2008.4591189","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591189","url":null,"abstract":"In this paper, Ni-Zn ferrite loaded coaxial line, using oil as insulation, with subnanosecond rise time at the input pulse voltage up to 360 kV into a 50 load is described. The dependence of the shock front development on the line length and pulse voltage was investigated. The experimental data were compared with analytical predictions of early theory. The experimental and expected results are shown to be in quite good agreement. A modified ferrite-loaded line with lower impedance was fabricated in order to increase its magnetic field. The ferrite loaded line showed stable work at pulse repetition frequency of 100 Hz and the shortest rise time of 0.7 ns has been achieved. Benson et al have proposed to use an axial magnetic field bias for further pulse sharpening. Magnetic bias conditions for the optimal pulse sharpening were tested.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80668712","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590921
B. Gweon, D. Kim, S. Moon, W. Choe, Sukhyun Song, Daeyun Kim, J. Shin
Summary form only given. A feasibility study of plasma cancer cell treatment was performed using a pin-type plasma jet. A 50 kHz AC power was used to generate the plasma in the ambient air assisted by the helium flow. The plasma gas temperature was maintained at the room temperature of 25degC to eliminate the thermal damages to the cell. The liver cancer cells of HEPG-2 and SK-HEP-1 were used as the treatment samples. The sample cells were prepared on the fibronectin coated slide glass for the sake of convenience of the microscopic observation process. The input voltage and the treatment time were controlled in the range of (750-1000) V and (30-120) s, respectively. After the plasma treatments, the sample cells were stained with the viability assay (ethidium homodimer and calcein AM) to make discrimination between live and dead cells. Then, the microscopy scan was performed from the plasma center up to about 1 cm. The necrotized cells as well as a void or cell free zone appeared starting at the input voltage of 800 V and the treatment time of 60 s, . The necrotized zone and the void were well matched to the plasma profile. Normal liver cell, THLE-2, was then treated for comparison with the liver cancer cells.
{"title":"Feasibility study of atmospheric pressure plasma treatments of HEPG-2 and SK-HEP-1 cancer cells","authors":"B. Gweon, D. Kim, S. Moon, W. Choe, Sukhyun Song, Daeyun Kim, J. Shin","doi":"10.1109/PLASMA.2008.4590921","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590921","url":null,"abstract":"Summary form only given. A feasibility study of plasma cancer cell treatment was performed using a pin-type plasma jet. A 50 kHz AC power was used to generate the plasma in the ambient air assisted by the helium flow. The plasma gas temperature was maintained at the room temperature of 25degC to eliminate the thermal damages to the cell. The liver cancer cells of HEPG-2 and SK-HEP-1 were used as the treatment samples. The sample cells were prepared on the fibronectin coated slide glass for the sake of convenience of the microscopic observation process. The input voltage and the treatment time were controlled in the range of (750-1000) V and (30-120) s, respectively. After the plasma treatments, the sample cells were stained with the viability assay (ethidium homodimer and calcein AM) to make discrimination between live and dead cells. Then, the microscopy scan was performed from the plasma center up to about 1 cm. The necrotized cells as well as a void or cell free zone appeared starting at the input voltage of 800 V and the treatment time of 60 s, . The necrotized zone and the void were well matched to the plasma profile. Normal liver cell, THLE-2, was then treated for comparison with the liver cancer cells.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77816678","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4591188
Weihua Jiang, T. Yokoo, K. Saiki, K. Hisayama, K. Narita, Ken Takayama, M. Wake, N. Shimizu
Pulsed power generators with repetition rates on the order of MHz have been developed by using semiconductor opening switch (SOS), static induction thyristor (SIThy), and silicon carbide junction field-effect-transistor (SiC-JFET). A compact SOS circuit based on inductive energy storage has been developed. It uses semiconductor switches for forward and reverse current control of the SOS diodes, instead of commonly used magnetic switch. The repetition rate has reached 500 kHz (burst) for output voltage pulse of 10 kV and pulse width of 15 ns (FWHM). A full-bridge switching unit using SIThy has been developed and tested for bipolar square voltage pulse generation of plusmn 2 kV for a 100-Omega load, at repetition rate of 1 MHz (burst). A stacked SiC-JFET switching unit consists of 4 devices (2S x 2P) has been operated for 2 kV and 20 A at repetition rate up to 5 MHz (burst). Important issues on switching characteristics, such as rise- time, heat loading, and balance between devices have been studied. The MHz-repetitive power modulators are expected to have various applications in the future, especially for high- energy accelerators and biological treatment.
{"title":"MHz pulsed power by semiconductor devices","authors":"Weihua Jiang, T. Yokoo, K. Saiki, K. Hisayama, K. Narita, Ken Takayama, M. Wake, N. Shimizu","doi":"10.1109/PLASMA.2008.4591188","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591188","url":null,"abstract":"Pulsed power generators with repetition rates on the order of MHz have been developed by using semiconductor opening switch (SOS), static induction thyristor (SIThy), and silicon carbide junction field-effect-transistor (SiC-JFET). A compact SOS circuit based on inductive energy storage has been developed. It uses semiconductor switches for forward and reverse current control of the SOS diodes, instead of commonly used magnetic switch. The repetition rate has reached 500 kHz (burst) for output voltage pulse of 10 kV and pulse width of 15 ns (FWHM). A full-bridge switching unit using SIThy has been developed and tested for bipolar square voltage pulse generation of plusmn 2 kV for a 100-Omega load, at repetition rate of 1 MHz (burst). A stacked SiC-JFET switching unit consists of 4 devices (2S x 2P) has been operated for 2 kV and 20 A at repetition rate up to 5 MHz (burst). Important issues on switching characteristics, such as rise- time, heat loading, and balance between devices have been studied. The MHz-repetitive power modulators are expected to have various applications in the future, especially for high- energy accelerators and biological treatment.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82221534","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 : 2008-06-15DOI: 10.1109/PLASMA.2008.4590860
J. Johnson, C. Ekdahl, W. Broste
Accurate and reliable beam position measurements are required to commission and operate the DARHT II Accelerator. The beam position monitor (BPM) system developed for use on the DARHT accelerator consists of 31 electro-magnetic detector assemblies, a computer network based data acquisition system, and analysis software. During each "shot" each BPM uses arrays of b-dot detectors to intercept the electron beam's changing magnetic field. The detector outputs are individually recorded. Post shot analysis of the data provides the beam current and position information. This paper will provide an overview of the system and give details regarding its performance.
{"title":"The DARHT II Accelerator beam position monitor system","authors":"J. Johnson, C. Ekdahl, W. Broste","doi":"10.1109/PLASMA.2008.4590860","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590860","url":null,"abstract":"Accurate and reliable beam position measurements are required to commission and operate the DARHT II Accelerator. The beam position monitor (BPM) system developed for use on the DARHT accelerator consists of 31 electro-magnetic detector assemblies, a computer network based data acquisition system, and analysis software. During each \"shot\" each BPM uses arrays of b-dot detectors to intercept the electron beam's changing magnetic field. The detector outputs are individually recorded. Post shot analysis of the data provides the beam current and position information. This paper will provide an overview of the system and give details regarding its performance.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82333145","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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