This paper describes a power supply designed for charging a 6.66 /spl mu/F capacitor to 30 kV in approximately 40 ms. The power supply should be capable of recharging the capacitor several times within a time frame of a few minutes. The primary supply would be a 500 VDC source, which could ultimately be supplied by a thermal battery. The major components of the power supply are a high-power inverter in H-bridge configuration followed by a step-up transformer. The switches for the H-bridge are high power isolated gate bipolar transistors (IGBTs). Control of the circuit is achieved by controlling the IGBTs by pulse width modulation (PWM). A microcontroller is being used to generate the required PWM signals. Use of the microcontroller provides a wide range of control flexibility and will allow for adaptation to the characteristics of the primary DC source. In order to minimize the volume of the transformer and at the same time limit the switching losses in the IGBTs, a switching frequency of 10 kHz was chosen. Circuit simulations show that 30 kV is reached after about 38 ms.
{"title":"Design of a 30 kV power supply for capacitor charging using short duty burst mode","authors":"M. Giesselmanns, E. Kristiansen","doi":"10.1109/PPC.1999.823596","DOIUrl":"https://doi.org/10.1109/PPC.1999.823596","url":null,"abstract":"This paper describes a power supply designed for charging a 6.66 /spl mu/F capacitor to 30 kV in approximately 40 ms. The power supply should be capable of recharging the capacitor several times within a time frame of a few minutes. The primary supply would be a 500 VDC source, which could ultimately be supplied by a thermal battery. The major components of the power supply are a high-power inverter in H-bridge configuration followed by a step-up transformer. The switches for the H-bridge are high power isolated gate bipolar transistors (IGBTs). Control of the circuit is achieved by controlling the IGBTs by pulse width modulation (PWM). A microcontroller is being used to generate the required PWM signals. Use of the microcontroller provides a wide range of control flexibility and will allow for adaptation to the characteristics of the primary DC source. In order to minimize the volume of the transformer and at the same time limit the switching losses in the IGBTs, a switching frequency of 10 kHz was chosen. Circuit simulations show that 30 kV is reached after about 38 ms.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"293 1","pages":"650-653 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73478314","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}
The present paper is devoted to the study of a new triggering scheme for discharge initiation which allows low triggering delay times and jitters. The device, which mainly comprises a carbon bridge is characterized by its low dimension and energy consumption. Fast imaging techniques coupled to electric measurements and spectroscopic investigations have allowed us to characterize the spatio-temporal evolution of the physical processes resulting in the triggering.
{"title":"Investigations on thermal triggering system for switching under vacuum","authors":"G. Bauville, A. Delmas, V. Puech","doi":"10.1109/PPC.1999.823721","DOIUrl":"https://doi.org/10.1109/PPC.1999.823721","url":null,"abstract":"The present paper is devoted to the study of a new triggering scheme for discharge initiation which allows low triggering delay times and jitters. The device, which mainly comprises a carbon bridge is characterized by its low dimension and energy consumption. Fast imaging techniques coupled to electric measurements and spectroscopic investigations have allowed us to characterize the spatio-temporal evolution of the physical processes resulting in the triggering.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"31 1","pages":"1133-1136 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73804783","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}
S. Rukin, G. Mesyats, S. Darznek, S. Lyubutin, A. Ponomarev, B. Slovikovsky, S. Timoshenkov, A. Bushlyakov, S. N. Tsiranov
This paper summarizes recent results of the study and development of high-power nanosecond generators employing a semiconductor opening switch. Physical processes, which underlie the operating principle of high-power opening switches based on nanosecond interruption of super-density currents in semiconductor diodes (SOS-effect), are discussed. Advances with SOS-diodes, which represent new high-voltage devices for nanosecond interruption of high-density currents, are discussed. The semiconductor structure of the SOS-diodes is compared with the structure of soft- and hard-recovery high-voltage rectifier diodes. The physical processes that occur in the semiconductor structure during pumping and interruption of the current are considered. SOS-generators having the output voltage from 0.1 to 1 MV, the pulse repetition frequency from 0.1 to 5 kHz, and the average output power of units to tens of kW, are described. Application of the SOS-generators is exemplified.
{"title":"SOS-based pulsed power: development and applications","authors":"S. Rukin, G. Mesyats, S. Darznek, S. Lyubutin, A. Ponomarev, B. Slovikovsky, S. Timoshenkov, A. Bushlyakov, S. N. Tsiranov","doi":"10.1109/PPC.1999.825435","DOIUrl":"https://doi.org/10.1109/PPC.1999.825435","url":null,"abstract":"This paper summarizes recent results of the study and development of high-power nanosecond generators employing a semiconductor opening switch. Physical processes, which underlie the operating principle of high-power opening switches based on nanosecond interruption of super-density currents in semiconductor diodes (SOS-effect), are discussed. Advances with SOS-diodes, which represent new high-voltage devices for nanosecond interruption of high-density currents, are discussed. The semiconductor structure of the SOS-diodes is compared with the structure of soft- and hard-recovery high-voltage rectifier diodes. The physical processes that occur in the semiconductor structure during pumping and interruption of the current are considered. SOS-generators having the output voltage from 0.1 to 1 MV, the pulse repetition frequency from 0.1 to 5 kHz, and the average output power of units to tens of kW, are described. Application of the SOS-generators is exemplified.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"17 1","pages":"153-156 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74082946","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}
The European Laboratory for Particle Physics (CERN) is constructing a Large Hadron Collider (LHC) to be installed in an existing 27 km circumference tunnel. The LHC will be equipped with fast pulsed magnet systems for injecting two counter-rotating hadron beams. Two pulsed systems, of 4 magnets and 4 pulse forming networks (PFNs) each, are required for this purpose. TRIUMF will build and test 5 resonant charging power supplies (RCPS) and nine PFNs and the associated thyratron switch units as part of the Canadian contribution to CERN LHC. Failures in the PFN capacitors may lead to incorrect beam deflections that may in turn damage LHC components. For this reason the reliability of the capacitors must be exceptionally high. Hence sample PFN capacitors were purchased and tested. The test procedure included discharging the PFN capacitors from 66 kV, into a 10.1 Ohm resistance, for 500,000 cycles, at a frequency of approximately 1 Hz. Subsequently the PFN capacitors were discharged from 66 kV into a 2.7 Ohm resistance, for 5,000 cycles. The value of the capacitance was measured before and after each test to determine whether the value remained stable. Voltage dependence of the capacitance value has also been measured. The test setups and results of the tests are presented in this paper.
{"title":"High current 66 kV tests on high stability PFN discharge capacitors for CERN LHC","authors":"M. Barnes, G. Wait","doi":"10.1109/PPC.1999.823628","DOIUrl":"https://doi.org/10.1109/PPC.1999.823628","url":null,"abstract":"The European Laboratory for Particle Physics (CERN) is constructing a Large Hadron Collider (LHC) to be installed in an existing 27 km circumference tunnel. The LHC will be equipped with fast pulsed magnet systems for injecting two counter-rotating hadron beams. Two pulsed systems, of 4 magnets and 4 pulse forming networks (PFNs) each, are required for this purpose. TRIUMF will build and test 5 resonant charging power supplies (RCPS) and nine PFNs and the associated thyratron switch units as part of the Canadian contribution to CERN LHC. Failures in the PFN capacitors may lead to incorrect beam deflections that may in turn damage LHC components. For this reason the reliability of the capacitors must be exceptionally high. Hence sample PFN capacitors were purchased and tested. The test procedure included discharging the PFN capacitors from 66 kV, into a 10.1 Ohm resistance, for 500,000 cycles, at a frequency of approximately 1 Hz. Subsequently the PFN capacitors were discharged from 66 kV into a 2.7 Ohm resistance, for 5,000 cycles. The value of the capacitance was measured before and after each test to determine whether the value remained stable. Voltage dependence of the capacitance value has also been measured. The test setups and results of the tests are presented in this paper.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"12 1","pages":"773-776 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74929608","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}
A total of 12 units of high power klystron-modulator systems are under continuous operation in the Pohang Light Source (PLS) linac. The peak powers of the modulator and the klystron are 200 MW and 80 MW, respectively. The klystron output frequency is 2856 MHz. Each klystron output is compressed with an SLED and supplied to four of three-meter long accelerating columns. Final electron energy of PLS linac is 2 GeV. The linac has been operated as a full energy injector for the PLS since December 1994. Annual operation hour of the system is about 5000 hours. Since the commissioning of the PLS linac, the total high voltage run time of an oldest unit among the 12 systems has been accumulated over 42,000-hours as of May 1999, and summation of all the units' high voltage run time is approximately 458,000 hours. The overall system availability is well over 90%. To enhance the klystron lifetime, a "cathode backheating" operation mode was adopted from May 1999. In this paper, the authors review overall system performance of the klystron-modulator system. The operational status of the klystrons and thyratrons, and the overall system availability statistics for the period of 1994 to May 1999 are also discussed.
{"title":"Klystron-modulator system performance in PLS 2-GeV electron linac","authors":"S. Nam, S. Park, S.W. Park, Y. Han","doi":"10.1109/PPC.1999.823677","DOIUrl":"https://doi.org/10.1109/PPC.1999.823677","url":null,"abstract":"A total of 12 units of high power klystron-modulator systems are under continuous operation in the Pohang Light Source (PLS) linac. The peak powers of the modulator and the klystron are 200 MW and 80 MW, respectively. The klystron output frequency is 2856 MHz. Each klystron output is compressed with an SLED and supplied to four of three-meter long accelerating columns. Final electron energy of PLS linac is 2 GeV. The linac has been operated as a full energy injector for the PLS since December 1994. Annual operation hour of the system is about 5000 hours. Since the commissioning of the PLS linac, the total high voltage run time of an oldest unit among the 12 systems has been accumulated over 42,000-hours as of May 1999, and summation of all the units' high voltage run time is approximately 458,000 hours. The overall system availability is well over 90%. To enhance the klystron lifetime, a \"cathode backheating\" operation mode was adopted from May 1999. In this paper, the authors review overall system performance of the klystron-modulator system. The operational status of the klystrons and thyratrons, and the overall system availability statistics for the period of 1994 to May 1999 are also discussed.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"39 1","pages":"963-966 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75682913","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}
Using semiconductor switches of high power thyristor and L-C resonant charging method, we developed a high repetitive impulse voltage generator. In this system, an improved charging circuit with diodes is adopted to lower its impedance of charging circuit and to implement uniform impulse voltage to circuit elements of diodes and resistances. With a five stage IG, high speed charging feature of 50 micro sec and preliminary result of 2 kHz repetitive operation are confirmed.
{"title":"Development of the high repetitive impulse voltage generator using semiconductor switches","authors":"K. Okamura, S. Kuroda, M. Maeyama","doi":"10.1109/PPC.1999.823637","DOIUrl":"https://doi.org/10.1109/PPC.1999.823637","url":null,"abstract":"Using semiconductor switches of high power thyristor and L-C resonant charging method, we developed a high repetitive impulse voltage generator. In this system, an improved charging circuit with diodes is adopted to lower its impedance of charging circuit and to implement uniform impulse voltage to circuit elements of diodes and resistances. With a five stage IG, high speed charging feature of 50 micro sec and preliminary result of 2 kHz repetitive operation are confirmed.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"26 1","pages":"807-810 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74822998","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}
F. Davanloo, R. Dussartt, M. Iosif, C. Collins, F. Agee
Photoconductive switching of the stacked Blumlein pulsers, developed at the University of Texas at Dallas, currently produces high power, nanosecond pulses with risetimes of the order of 200 ps. The device has a compact geometry and is commutated by a single GaAs switch triggered by a low power laser diode array. This report presents the progress toward improving the high gain switch operation and lifetime in stacked Blumlein pulsers. Feasibility of the use of amorphic diamond to enhance the switch operation and longevity is discussed. Improvement in switch lifetime was demonstrated by coating the triggered face of a GaAs switch cathode with highly adhesive film of amorphic diamond.
德克萨斯大学达拉斯分校(University of Texas at Dallas)开发的堆叠Blumlein脉冲的光导开关，目前可产生高功率、纳秒级脉冲，上升时间约为200 ps。该器件具有紧凑的几何结构，由一个低功率激光二极管阵列触发的单一砷化镓开关进行整流。本文介绍了在改进堆叠Blumlein脉冲的高增益开关操作和寿命方面取得的进展。讨论了使用非晶金刚石提高开关操作和寿命的可行性。通过在GaAs开关阴极的触发面涂覆非晶金刚石的高粘接膜，证明了开关寿命的提高。
{"title":"Photoconductive switch enhancements and lifetime studies for use in stacked Blumlein pulsers","authors":"F. Davanloo, R. Dussartt, M. Iosif, C. Collins, F. Agee","doi":"10.1109/PPC.1999.825475","DOIUrl":"https://doi.org/10.1109/PPC.1999.825475","url":null,"abstract":"Photoconductive switching of the stacked Blumlein pulsers, developed at the University of Texas at Dallas, currently produces high power, nanosecond pulses with risetimes of the order of 200 ps. The device has a compact geometry and is commutated by a single GaAs switch triggered by a low power laser diode array. This report presents the progress toward improving the high gain switch operation and lifetime in stacked Blumlein pulsers. Feasibility of the use of amorphic diamond to enhance the switch operation and longevity is discussed. Improvement in switch lifetime was demonstrated by coating the triggered face of a GaAs switch cathode with highly adhesive film of amorphic diamond.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"69 1","pages":"320-323 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77468354","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}
I. Lisitsyn, Y. Teramoto, S. Kohno, S. Katsuki, H. Akiyama
The modified snowplow model of a plasma opening switch is proposed. The conduction phase is divided into two parts. The first part lasts until the current-carrying channel reaches the load end of the pre-filled plasma. The second part, the transition phase to the opening, is characterized by the motion of current carrying channel downstream the initial plasma location. The equation of motion of the current channel is solved for both phases and the snowplow mechanism for high-voltage pulse generation is developed. The theoretical dependencies are in good agreement with the experiment, which includes interferometry and optical fiber measurements of current front translation. The qualitative model of the switch plasma behavior is proposed and used in explanations of various plasma opening switch features.
{"title":"Snowplow modeling of a long-conduction-time plasma opening switch","authors":"I. Lisitsyn, Y. Teramoto, S. Kohno, S. Katsuki, H. Akiyama","doi":"10.1109/PPC.1999.823640","DOIUrl":"https://doi.org/10.1109/PPC.1999.823640","url":null,"abstract":"The modified snowplow model of a plasma opening switch is proposed. The conduction phase is divided into two parts. The first part lasts until the current-carrying channel reaches the load end of the pre-filled plasma. The second part, the transition phase to the opening, is characterized by the motion of current carrying channel downstream the initial plasma location. The equation of motion of the current channel is solved for both phases and the snowplow mechanism for high-voltage pulse generation is developed. The theoretical dependencies are in good agreement with the experiment, which includes interferometry and optical fiber measurements of current front translation. The qualitative model of the switch plasma behavior is proposed and used in explanations of various plasma opening switch features.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"106 1","pages":"818-821 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77474202","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}
The crossed-field secondary emission (CFSE) diode is an electron source of a magnetron type that is capable of producing high current tubular electron beams in the range of 10/sup 2/-10/sup 3/ A. The electron beam is generated by means of a self-sustained secondary emission thus making the CFSE diode an essentially cold electron source. This results in a very high temporal stability of the electron beam which has a wall thickness of /spl sim/1 mm. The above features, together with an extremely simple and compact design, make the CFSE electron source attractive in various applications including electron accelerator systems and high power microwave production. This work has been aimed at determining the conditions under which the CFSE electron source produces high electron currents while retaining simultaneously reliable self-excitation. Several methods for achieving that goal have been identified and these have been validated experimentally and analysed in some detail. As a result of this research, stable electron beams with perveance of /spl sim/85 /spl mu/A/V/sup 3/2/ and current /spl sim/240 A were generated.
{"title":"High current operation of the crossed-field secondary emission electron source","authors":"Y. Saveliev, W. Sibbett, D. Parkes","doi":"10.1109/PPC.1999.825500","DOIUrl":"https://doi.org/10.1109/PPC.1999.825500","url":null,"abstract":"The crossed-field secondary emission (CFSE) diode is an electron source of a magnetron type that is capable of producing high current tubular electron beams in the range of 10/sup 2/-10/sup 3/ A. The electron beam is generated by means of a self-sustained secondary emission thus making the CFSE diode an essentially cold electron source. This results in a very high temporal stability of the electron beam which has a wall thickness of /spl sim/1 mm. The above features, together with an extremely simple and compact design, make the CFSE electron source attractive in various applications including electron accelerator systems and high power microwave production. This work has been aimed at determining the conditions under which the CFSE electron source produces high electron currents while retaining simultaneously reliable self-excitation. Several methods for achieving that goal have been identified and these have been validated experimentally and analysed in some detail. As a result of this research, stable electron beams with perveance of /spl sim/85 /spl mu/A/V/sup 3/2/ and current /spl sim/240 A were generated.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"7 1","pages":"420-424 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79350345","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}
Studies conducted over the past several years have shown that dissociative electron attachment to highly-excited states of molecules have extremely large cross sections. Implications of this process for pulsed discharges used for H/sup -/ generation, material processing, and plasma remediation are discussed.
{"title":"Enhanced electron attachment to highly-excited molecules and its applications in pulsed plasmas","authors":"L. A. Pinnaduwage, W. Ding, D. McCorkle, C.Y. Ma","doi":"10.1109/PPC.1999.823770","DOIUrl":"https://doi.org/10.1109/PPC.1999.823770","url":null,"abstract":"Studies conducted over the past several years have shown that dissociative electron attachment to highly-excited states of molecules have extremely large cross sections. Implications of this process for pulsed discharges used for H/sup -/ generation, material processing, and plasma remediation are discussed.","PeriodicalId":11209,"journal":{"name":"Digest of Technical Papers. 12th IEEE International Pulsed Power Conference. (Cat. No.99CH36358)","volume":"65 1","pages":"1322-1325 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1999-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76873166","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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