Pub Date : 2008-07-06DOI: 10.1109/PLASMA.2008.4591001
E. Grabovski, V. Smirnov, V. Aleksandrov, M. Fedulov, I. Frolov, A. Gribov, A. N. Gritsouk, Y. Laukhin, S. F. Medovshikov, K. Mitrofanov, G. M. Oleinik, A. Samokhin, G. Volkov, V. I. Zaĭtsev, A. Lototsky, A. Zhitlukhin, V. Afanasyev, V. P. Bakhtin, N. Efremof, G. N. Khomutinnikov, M. K. Krylov, A. A. Nikolashin, S. Seryakov, P. Sasorov, V. Gasilov, S. V. D'yachenko, O. Olkhovskaya, E. Kartasheva, A. Boldarev
Work on Z-pinches, that is under way at the SRC RF TRINITI, is aimed at the resolution of two basic problems: to investigate the problem of physics of X-ray generation in a Z-pinch scheme with the goal of its application for ICF at the "Angara-5-1" facility to develop the engineering aspects of multimegampere facilities intended for using them in a Z-pinch scheme for ICF and making the "Baikal" project. At the "Angara-5-1 facility" the measurements of plasma production rates for the wire and foam liners were taken. It has been shown that for Mo, W, Cu, Fe, and Al a current sheath with a radial thickness much larger than the skin- layer forms. The value of the plasma production rate for these metals was obtained. In the case of the liner from agar-agar foam no formation of such a layer was observed. The spectral measurements taken in hybrid Al-W liners make it possible to estimate the electron temperature and concentration from the spectrum of Al ions. It is also shown that an addition of tungsten into the array compound at a constant mass leads to a decrease of not only the electron temperature but also the final radius of stagnation. The measurements of the hard X-radiation appearing at the moment close to a peak of the X-ray pulse are likely to indicate the formation of an several kiloamperes electron beam. The experiments with conical arrays consisting of tungsten wires demonstrate the effects which arise when the wire array is imploded both in radial and axial directions. For large cone angles there appear two separate radiating regions. The corresponding X-ray pulses have a double-peak structure. Calculations of such liner compression are used to test the programs describing both radial and axial plasma compression. The results obtained at the IMM RAS fairly well provide a quantitative description of the X-ray pulse structure. Such conical liners prove to be a promising tool to test complicated RMHD codes. A pulse generation scheme relevant to the "Baikal" project is under development at the MOL facility. A 30-fold reliable current multiplication in the inductive storage has been obtained. The storage energy was effectively transferred to the subsequent stage of formation, i.e. a magnetic amplifier. The current in the latter was multiplied by a factor of 1.55. At the "Angara-5-1" facility the MEVL code reporting the process of magnetic insulation arising in the in-parallel- connected magnetically insulated vacuum lines has been tested.
{"title":"The “Baikal” project and investigations of radiating Z-pinches at the “Angara-5-1” facility","authors":"E. Grabovski, V. Smirnov, V. Aleksandrov, M. Fedulov, I. Frolov, A. Gribov, A. N. Gritsouk, Y. Laukhin, S. F. Medovshikov, K. Mitrofanov, G. M. Oleinik, A. Samokhin, G. Volkov, V. I. Zaĭtsev, A. Lototsky, A. Zhitlukhin, V. Afanasyev, V. P. Bakhtin, N. Efremof, G. N. Khomutinnikov, M. K. Krylov, A. A. Nikolashin, S. Seryakov, P. Sasorov, V. Gasilov, S. V. D'yachenko, O. Olkhovskaya, E. Kartasheva, A. Boldarev","doi":"10.1109/PLASMA.2008.4591001","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591001","url":null,"abstract":"Work on Z-pinches, that is under way at the SRC RF TRINITI, is aimed at the resolution of two basic problems: to investigate the problem of physics of X-ray generation in a Z-pinch scheme with the goal of its application for ICF at the \"Angara-5-1\" facility to develop the engineering aspects of multimegampere facilities intended for using them in a Z-pinch scheme for ICF and making the \"Baikal\" project. At the \"Angara-5-1 facility\" the measurements of plasma production rates for the wire and foam liners were taken. It has been shown that for Mo, W, Cu, Fe, and Al a current sheath with a radial thickness much larger than the skin- layer forms. The value of the plasma production rate for these metals was obtained. In the case of the liner from agar-agar foam no formation of such a layer was observed. The spectral measurements taken in hybrid Al-W liners make it possible to estimate the electron temperature and concentration from the spectrum of Al ions. It is also shown that an addition of tungsten into the array compound at a constant mass leads to a decrease of not only the electron temperature but also the final radius of stagnation. The measurements of the hard X-radiation appearing at the moment close to a peak of the X-ray pulse are likely to indicate the formation of an several kiloamperes electron beam. The experiments with conical arrays consisting of tungsten wires demonstrate the effects which arise when the wire array is imploded both in radial and axial directions. For large cone angles there appear two separate radiating regions. The corresponding X-ray pulses have a double-peak structure. Calculations of such liner compression are used to test the programs describing both radial and axial plasma compression. The results obtained at the IMM RAS fairly well provide a quantitative description of the X-ray pulse structure. Such conical liners prove to be a promising tool to test complicated RMHD codes. A pulse generation scheme relevant to the \"Baikal\" project is under development at the MOL facility. A 30-fold reliable current multiplication in the inductive storage has been obtained. The storage energy was effectively transferred to the subsequent stage of formation, i.e. a magnetic amplifier. The current in the latter was multiplied by a factor of 1.55. At the \"Angara-5-1\" facility the MEVL code reporting the process of magnetic insulation arising in the in-parallel- connected magnetically insulated vacuum lines has been tested.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76020603","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.2008.4590887
Kenn Su Kim, G. Soucy, A. Moradian, J. Mostaghimi
Numerical and experimental studies have been performed on the continuous synthesis of single-walled carbon nanotubes (SWNT) in an inductively coupled thermal plasma reactor, in order to get better understanding of the effects of process parameters (ex., plasma gas composition, feed rate, and plasma power) on the SWNT formation and to determine the optimal process environment most suitable for SWNT synthesis. In the numerical study, a self consistent numerical model, which consists of several sub-models (i.e., plasma generation, plasma-particle interaction, nucleation and transport of SWNT precursors, and chemical reaction), is developed to accurately simulate the SWNT synthesis process in the entire region of the induction plasma system. And then, a parametric study of various system and synthesis parameters was conducted experimentally to confirm validity of the numerical model. Base on the numerical and experimental results, the appropriate operating conditions of the RF induction plasma process are suggested for an effective synthesis of SWNT.
{"title":"Modeling of continuous synthesis of single-walled carbon nanotubes by RF induction thermal plasma","authors":"Kenn Su Kim, G. Soucy, A. Moradian, J. Mostaghimi","doi":"10.1109/PLASMA.2008.4590887","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590887","url":null,"abstract":"Numerical and experimental studies have been performed on the continuous synthesis of single-walled carbon nanotubes (SWNT) in an inductively coupled thermal plasma reactor, in order to get better understanding of the effects of process parameters (ex., plasma gas composition, feed rate, and plasma power) on the SWNT formation and to determine the optimal process environment most suitable for SWNT synthesis. In the numerical study, a self consistent numerical model, which consists of several sub-models (i.e., plasma generation, plasma-particle interaction, nucleation and transport of SWNT precursors, and chemical reaction), is developed to accurately simulate the SWNT synthesis process in the entire region of the induction plasma system. And then, a parametric study of various system and synthesis parameters was conducted experimentally to confirm validity of the numerical model. Base on the numerical and experimental results, the appropriate operating conditions of the RF induction plasma process are suggested for an effective synthesis of SWNT.","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":"73499225","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.2008.4590799
O. Louksha, G. Sominski, D. Samsonov, G. Dammertz, B. Piosczyk, M. Thumm
Summary form only given as follows. One of the important sources of helical electron beam quality deterioration in gyrotrons is inhomogeneous electron emission from thermionic cathodes of magnetron-injection guns. A high vacuum test stand has been manufactured at SPbSPU for diagnostics and ion treatment of large-size gyrotron cathodes. This facility is equipped with a source of potassium ions providing an ion current density on the cathode up to 2times10-6 A/cm2 and an ion energy up to 11 keV. Rotating the cathode, we select cathode surface areas with anomalous emission for their treatment by ion bombardment. Potassium was chosen for these experiments primarily due to the simplicity of an ion source based on surface ionization of its atoms. Besides, our measurements show that potassium atoms deposited on the emitter surface do not practically influence the emission activity because of rapid evaporation of these atoms from the heated cathode surface at operating temperature. Therefore, such atoms can be used for modeling of processes on the cathode surface in gyrotrons being under the action of bombardment by the ions of the residual gases. The experiments with the LaB6 cathode showed the possibility of emission homogeneity improvement for this cathode due to the deactivation of the emissive surface areas with high electron emission resulting from their treatment by potassium ions. Ion bombardment of the W-Ba cathode caused an increase of electron emission from the treated area. The measurements with this cathode were made for wide ranges of temperature up to ~1100degC and of cathode current density up to ~3 A/cm2. The degree of emission increase resulting from ion bombardment depends on treatment duration, ion energy and initial activity of the treated area. A maximum activation enhancement factor of 2.5 was achieved. In the report, we will discuss the causes of cathode emission changes due to ion treatment and the mechanisms of emission homogeneity degradation in gyrotrons connected with the bombardment of the cathode surface by ion flows.
摘要形式只提供如下。磁控管注入枪热离子阴极的不均匀电子发射是导致回旋管螺旋电子束质量恶化的重要原因之一。研制了用于大尺寸回旋管阴极诊断和离子处理的高真空试验台。该设备配备了钾离子源，阴极上的离子电流密度高达2倍10-6 a /cm2，离子能量高达11 keV。旋转阴极，选择具有异常发射的阴极表面区域进行离子轰击处理。这些实验之所以选择钾，主要是因为基于其原子表面电离的离子源很简单。此外，我们的测量表明，沉积在发射极表面的钾原子实际上并不影响发射活性，因为这些原子在工作温度下从加热的阴极表面迅速蒸发。因此，这些原子可以用来模拟回旋管阴极表面在残余气体离子轰击作用下的过程。LaB6阴极的实验表明，由于钾离子处理导致高电子发射区的失活，LaB6阴极的发射均匀性有可能得到改善。离子轰击W-Ba阴极导致处理区域的电子发射增加。该阴极的测量温度范围可达~1100℃，阴极电流密度可达~3 A/cm2。离子轰击引起的发射增加程度取决于处理时间、离子能量和处理区域的初始活度。最大活化增强因子达到2.5。在报告中，我们将讨论离子处理导致阴极发射变化的原因，以及与离子流轰击阴极表面有关的回旋管发射均匀性退化的机制。
{"title":"Effect of ion bombardment on emission characteristics of gyrotron cathodes","authors":"O. Louksha, G. Sominski, D. Samsonov, G. Dammertz, B. Piosczyk, M. Thumm","doi":"10.1109/PLASMA.2008.4590799","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590799","url":null,"abstract":"Summary form only given as follows. One of the important sources of helical electron beam quality deterioration in gyrotrons is inhomogeneous electron emission from thermionic cathodes of magnetron-injection guns. A high vacuum test stand has been manufactured at SPbSPU for diagnostics and ion treatment of large-size gyrotron cathodes. This facility is equipped with a source of potassium ions providing an ion current density on the cathode up to 2times10-6 A/cm2 and an ion energy up to 11 keV. Rotating the cathode, we select cathode surface areas with anomalous emission for their treatment by ion bombardment. Potassium was chosen for these experiments primarily due to the simplicity of an ion source based on surface ionization of its atoms. Besides, our measurements show that potassium atoms deposited on the emitter surface do not practically influence the emission activity because of rapid evaporation of these atoms from the heated cathode surface at operating temperature. Therefore, such atoms can be used for modeling of processes on the cathode surface in gyrotrons being under the action of bombardment by the ions of the residual gases. The experiments with the LaB6 cathode showed the possibility of emission homogeneity improvement for this cathode due to the deactivation of the emissive surface areas with high electron emission resulting from their treatment by potassium ions. Ion bombardment of the W-Ba cathode caused an increase of electron emission from the treated area. The measurements with this cathode were made for wide ranges of temperature up to ~1100degC and of cathode current density up to ~3 A/cm2. The degree of emission increase resulting from ion bombardment depends on treatment duration, ion energy and initial activity of the treated area. A maximum activation enhancement factor of 2.5 was achieved. In the report, we will discuss the causes of cathode emission changes due to ion treatment and the mechanisms of emission homogeneity degradation in gyrotrons connected with the bombardment of the cathode surface by ion flows.","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":"73737496","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.2008.4590902
I. J. Van der Walt, J. Havenga, J. Nel
Conventional linear DC plasma torches are known to have a relative long tail flame wherein a high temperature chemical reaction can be performed or where the plasma can act as a heat transfer medium. Introducing solid particles into these plasma torches generally destabilizes the plasma and may cause extensive erosion on the anode, thus shortening the torch operational time significantly. In this torch the solid particles are exposed to the arc temperature and not only the tail flame temperature. This torch enables one to introduce solid particles in very close proximity of the plasma arc and if the particle velocity is optimized, the particles may even penetrate the arc. This paper presents the design and typical operating parameters of a V-type plasma system, and discuses the advantages and disadvantages of such a system.
{"title":"A thermal non-transfer arc V-type torch plasma","authors":"I. J. Van der Walt, J. Havenga, J. Nel","doi":"10.1109/PLASMA.2008.4590902","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590902","url":null,"abstract":"Conventional linear DC plasma torches are known to have a relative long tail flame wherein a high temperature chemical reaction can be performed or where the plasma can act as a heat transfer medium. Introducing solid particles into these plasma torches generally destabilizes the plasma and may cause extensive erosion on the anode, thus shortening the torch operational time significantly. In this torch the solid particles are exposed to the arc temperature and not only the tail flame temperature. This torch enables one to introduce solid particles in very close proximity of the plasma arc and if the particle velocity is optimized, the particles may even penetrate the arc. This paper presents the design and typical operating parameters of a V-type plasma system, and discuses the advantages and disadvantages of such a system.","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":"73837016","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.2008.4590999
D. Osin, E. Kroupp, A. Starobinets, V. Fisher, V. Bernshtam, Y. Maron, I. Uschmann, E. Foerster, A. Fisher, B. Jones, P. Lepell, M. Cuneo, C. Deeney
Summary form only given. The time-history of the ion-kinetic energy Ek ion throughout the stagnation phase of a neon-puff, 500 ns, 600 kA, Z-pinch implosion was determined. The X-ray spectroscopic system provides a resolving power of 6700 and four consecutive time gated (~1 ns) spectra. A simultaneous axial imaging allows for studying the ion kinetic energy at 0.1-mm-resolution along the pinch column. Ek ion in the stagnating plasma is obtained from the Doppler contribution to the line shapes of the Lyalpha satellites, verified to be optically thin. The line shapes give the ion velocity distribution just before stagnation (non Gaussian) and throughout the 10-ns-long stagnation (Gaussian-like). Ek ion was found to be sime12 keV early at stagnation, dropping down during the stagnation to the electron thermal energy (sime300 eV). The time scale of ion-kinetic energy loss is longer (cong2 ns) than expected from the ion and electron collisional thermalization time (cong0.1 ns). A plausible explanation of the data is that upon reaching the pinch axis, the stagnating plasma develops a turbulent flow, in which most of the implosion energy is stored. The turbulent motion then dissipates into ion heat more slowly than the ion-electron energy equilibration time, which causes Tion to be low, resulting in a slowing down of the ion energy transfer to electrons and to radiation. Detailed study of the experimental line shapes is used to examine this explanation. Axially-resolved measurements of the time-dependent stagnating-plasma properties, and the absolute total neon K radiation show that, within the experimental uncertainties, the observed total ion-kinetic energy accounts for the total radiation emitted from this plasma. These findings, and assuming the explanation given above, can be used to discriminate between the thermal and the turbulent ion kinetic energies throughout the stagnation. Results on the thus-inferred Tion will be presented. Comparisons will be made to implosion velocities and time-resolved line-widths observed in wire-array implosions on the Z machine.
{"title":"Experimental study of the ion thermalization at a Z-pinch at stagnation","authors":"D. Osin, E. Kroupp, A. Starobinets, V. Fisher, V. Bernshtam, Y. Maron, I. Uschmann, E. Foerster, A. Fisher, B. Jones, P. Lepell, M. Cuneo, C. Deeney","doi":"10.1109/PLASMA.2008.4590999","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590999","url":null,"abstract":"Summary form only given. The time-history of the ion-kinetic energy Ek ion throughout the stagnation phase of a neon-puff, 500 ns, 600 kA, Z-pinch implosion was determined. The X-ray spectroscopic system provides a resolving power of 6700 and four consecutive time gated (~1 ns) spectra. A simultaneous axial imaging allows for studying the ion kinetic energy at 0.1-mm-resolution along the pinch column. Ek ion in the stagnating plasma is obtained from the Doppler contribution to the line shapes of the Lyalpha satellites, verified to be optically thin. The line shapes give the ion velocity distribution just before stagnation (non Gaussian) and throughout the 10-ns-long stagnation (Gaussian-like). Ek ion was found to be sime12 keV early at stagnation, dropping down during the stagnation to the electron thermal energy (sime300 eV). The time scale of ion-kinetic energy loss is longer (cong2 ns) than expected from the ion and electron collisional thermalization time (cong0.1 ns). A plausible explanation of the data is that upon reaching the pinch axis, the stagnating plasma develops a turbulent flow, in which most of the implosion energy is stored. The turbulent motion then dissipates into ion heat more slowly than the ion-electron energy equilibration time, which causes Tion to be low, resulting in a slowing down of the ion energy transfer to electrons and to radiation. Detailed study of the experimental line shapes is used to examine this explanation. Axially-resolved measurements of the time-dependent stagnating-plasma properties, and the absolute total neon K radiation show that, within the experimental uncertainties, the observed total ion-kinetic energy accounts for the total radiation emitted from this plasma. These findings, and assuming the explanation given above, can be used to discriminate between the thermal and the turbulent ion kinetic energies throughout the stagnation. Results on the thus-inferred Tion will be presented. Comparisons will be made to implosion velocities and time-resolved line-widths observed in wire-array implosions on the Z machine.","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":"75804450","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.2008.4590976
M. Teschke, J. Engemann
Summary form only given. A new and innovative concept for atmospheric pressure, low voltage plasma generation was presented recently. Different structures based on piezoelectric ceramics are proposed. All of them can directly be driven by low voltage (some 10 volts typically) at low frequency (typically some 10 kHz). This is very advantageous because of safety reasons as well as simple and cheap power supply systems. This technology has the potential becoming a bulk product e.g. in medical and handyman applications. The touch of plasma and plasma source is not harmful, because the electrical energy is distributed uniformly in the whole structure. Thus, the local electrical potential breaks down immediately and there is no risk for electrical shock. First prototypes are constructed successfully. However, technical challenges remain. For the functionality of these structures, the generation of a complex distribution of remanent polarization is necessary. This process is called poling. Only very simple methods are known from literature, so far. They are inappropriate for the presented structures and new poling techniques have been developed. Some will be presented and discussed in detail. Another challenge is the realization of complex, extended and glued structures needed for up-scaling. First promising results have been achieved and will be presented, too.
{"title":"A (r)evolutionary concept for low voltage plasma generation at atmospheric pressure","authors":"M. Teschke, J. Engemann","doi":"10.1109/PLASMA.2008.4590976","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590976","url":null,"abstract":"Summary form only given. A new and innovative concept for atmospheric pressure, low voltage plasma generation was presented recently. Different structures based on piezoelectric ceramics are proposed. All of them can directly be driven by low voltage (some 10 volts typically) at low frequency (typically some 10 kHz). This is very advantageous because of safety reasons as well as simple and cheap power supply systems. This technology has the potential becoming a bulk product e.g. in medical and handyman applications. The touch of plasma and plasma source is not harmful, because the electrical energy is distributed uniformly in the whole structure. Thus, the local electrical potential breaks down immediately and there is no risk for electrical shock. First prototypes are constructed successfully. However, technical challenges remain. For the functionality of these structures, the generation of a complex distribution of remanent polarization is necessary. This process is called poling. Only very simple methods are known from literature, so far. They are inappropriate for the presented structures and new poling techniques have been developed. Some will be presented and discussed in detail. Another challenge is the realization of complex, extended and glued structures needed for up-scaling. First promising results have been achieved and will be presented, too.","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":"73984842","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.2008.4590881
E. Waisman, M. Cuneo, B. Jones, M. Jones, R. Lemke, D. Sinars, W. Stygar
We present our analysis obtaining from experimental data approximate lower bounds for the kinetic energy and magnetic flux dissipation for single and nested wire arrays and gas puffs on the former and present configurations of the Z pulsed- power accelerator at Sandia National Laboratories. The procedure we employ, applied to electrical and x-ray energy measurements, utilizes the pinch energy balance to determine lower bounds for the plasma kinetic energy just before the main pinch reaches the axis and for the magnetic flux dissipation during stagnation. From the lower bound for the dissipated flux a lower bound for pinch resistance after x-ray peak power is estimated. We present the results of applying this Energy Balance Procedure (EBP) to tungsten wire array, nested wire array and gas puff z-pinches.
{"title":"Lower bounds for the kinetic energy and resistance of z-pinches on Z","authors":"E. Waisman, M. Cuneo, B. Jones, M. Jones, R. Lemke, D. Sinars, W. Stygar","doi":"10.1109/PLASMA.2008.4590881","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590881","url":null,"abstract":"We present our analysis obtaining from experimental data approximate lower bounds for the kinetic energy and magnetic flux dissipation for single and nested wire arrays and gas puffs on the former and present configurations of the Z pulsed- power accelerator at Sandia National Laboratories. The procedure we employ, applied to electrical and x-ray energy measurements, utilizes the pinch energy balance to determine lower bounds for the plasma kinetic energy just before the main pinch reaches the axis and for the magnetic flux dissipation during stagnation. From the lower bound for the dissipated flux a lower bound for pinch resistance after x-ray peak power is estimated. We present the results of applying this Energy Balance Procedure (EBP) to tungsten wire array, nested wire array and gas puff z-pinches.","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":"72725683","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.2008.4591167
I. Kourakis, P. Shukla, V. Koukouloyannis, B. Farokhi
The nonlinear aspects of dust motion in one- (1D) and two-dimensional (2D) dust lattices are reviewed. Horizontal (longitudinal, acoustic) as well as vertical (transverse, optic-like) dust grain motion in 1D monolayer is studied. Dust crystals are shown to support nonlinear kink-shaped solitary excitations (density solitons), related to longitudinal (in-plane) dust grain displacement, as well as modulated envelope localized modes associated with either longitudinal (in-plane, acoustic) or transverse (off-plane, inverse-optic) oscillations. Highly localized excitations ("Discrete Breathers"), associated with transverse dust-grain motion in 1D dust crystals, may also exist, as recently shown from first principles. Hexagonal (2D) dust lattices sustain modulated envelope structures, formed via modulational instability of in-plane vibrations. Discrete analysis of hexagonal crystals also suggests the occurrence of ultra-localized modes and vortices. With the exception of longitudinal density solitons, the above theoretical predictions have not yet been tested in the laboratory. This provides a challenging test-bed for experimental investigations, which will hopefully confirm these results.
{"title":"Localized excitations in dusty plasma crystals: A survey of theoretical results","authors":"I. Kourakis, P. Shukla, V. Koukouloyannis, B. Farokhi","doi":"10.1109/PLASMA.2008.4591167","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591167","url":null,"abstract":"The nonlinear aspects of dust motion in one- (1D) and two-dimensional (2D) dust lattices are reviewed. Horizontal (longitudinal, acoustic) as well as vertical (transverse, optic-like) dust grain motion in 1D monolayer is studied. Dust crystals are shown to support nonlinear kink-shaped solitary excitations (density solitons), related to longitudinal (in-plane) dust grain displacement, as well as modulated envelope localized modes associated with either longitudinal (in-plane, acoustic) or transverse (off-plane, inverse-optic) oscillations. Highly localized excitations (\"Discrete Breathers\"), associated with transverse dust-grain motion in 1D dust crystals, may also exist, as recently shown from first principles. Hexagonal (2D) dust lattices sustain modulated envelope structures, formed via modulational instability of in-plane vibrations. Discrete analysis of hexagonal crystals also suggests the occurrence of ultra-localized modes and vortices. With the exception of longitudinal density solitons, the above theoretical predictions have not yet been tested in the laboratory. This provides a challenging test-bed for experimental investigations, which will hopefully confirm these results.","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":"74580859","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.2008.4591072
T. Nayuki, Y. Oishi, T. Fujii, K. Nemoto, A. Zhidkov
Hard X-ray over 100 keV is known to be an important tool for nondestructive diagnosis of metal structures. These X-rays can be generated from radioisotopes such as 192Ir or 60Co, or from an X-ray tube. However, these isotopes require a severe control for a safely handling and the dimension of the X-ray tube is too large to measure in situ. The interaction of an ultraintense femtosecond laser pulse with matter acts as a source of hard X-rays produced by bremsstrahlung of relativistic electrons and characteristic line emission from the matter. The main drawback of this kind of X-ray source is the extremely high cost and the large scale of high-power femtosecond laser systems. In this study, we report on the development of a 104*82*75 mm3-sized X-ray source, which is driven by laser pulses of only 20 mJ energy and 40 fs duration. The laser beam with 12.7 mm diameter is delivered by small optics and is focused onto a tape target made of copper 5 mum thick. A measured electron temperature of energetic part was 340 keV, which agreed with that of two-dimensional collisional particle-in-cell simulations including plasma ionization. The irradiation size of the X-ray source at the laser focus was 16 mum measured by means of a knife-edge shadowgraphy. Using this compact X-ray source, a transmission image of a sample made of aluminum 10 mm thick was obtained with 100-shot laser accumulations. An estimated X-ray temperature of energetic part was 35 keV, which agreed with the electron temperature of low energy part.
{"title":"Development of a compact laser-plasma hard x-ray source","authors":"T. Nayuki, Y. Oishi, T. Fujii, K. Nemoto, A. Zhidkov","doi":"10.1109/PLASMA.2008.4591072","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591072","url":null,"abstract":"Hard X-ray over 100 keV is known to be an important tool for nondestructive diagnosis of metal structures. These X-rays can be generated from radioisotopes such as 192Ir or 60Co, or from an X-ray tube. However, these isotopes require a severe control for a safely handling and the dimension of the X-ray tube is too large to measure in situ. The interaction of an ultraintense femtosecond laser pulse with matter acts as a source of hard X-rays produced by bremsstrahlung of relativistic electrons and characteristic line emission from the matter. The main drawback of this kind of X-ray source is the extremely high cost and the large scale of high-power femtosecond laser systems. In this study, we report on the development of a 104*82*75 mm3-sized X-ray source, which is driven by laser pulses of only 20 mJ energy and 40 fs duration. The laser beam with 12.7 mm diameter is delivered by small optics and is focused onto a tape target made of copper 5 mum thick. A measured electron temperature of energetic part was 340 keV, which agreed with that of two-dimensional collisional particle-in-cell simulations including plasma ionization. The irradiation size of the X-ray source at the laser focus was 16 mum measured by means of a knife-edge shadowgraphy. Using this compact X-ray source, a transmission image of a sample made of aluminum 10 mm thick was obtained with 100-shot laser accumulations. An estimated X-ray temperature of energetic part was 35 keV, which agreed with the electron temperature of low energy part.","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":"78807987","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.2008.4590880
A. Agafonov, V. Romanova, A. R. Mingaleev, T. Shelkovenko, S. Pikuz, I. Blesener, B. Kusse, D. Hammer
Results of experimental studies of the spatial and temporal characteristics of the hard X-rays generated by high-current electron beams in X-pinch experiments on the XP (Cornell University) and BIN (LPI RAS) pulsed power generators are presented. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometries are discussed. Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Results of computer simulation of electron beam propagation from X-pinch to Faraday cup give the limits of measured current for beams having different energy spread. We emphasize the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Different schemes for beam space-charge neutralization are discussed. Longitudinal neutralization is thought to be the most important method because it enables transport of beams with close to the Alfven current. Experimental and computer simulation results on electron beam generation are compared.
{"title":"Hard X-rays and high-current electron beams from X-pinches","authors":"A. Agafonov, V. Romanova, A. R. Mingaleev, T. Shelkovenko, S. Pikuz, I. Blesener, B. Kusse, D. Hammer","doi":"10.1109/PLASMA.2008.4590880","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590880","url":null,"abstract":"Results of experimental studies of the spatial and temporal characteristics of the hard X-rays generated by high-current electron beams in X-pinch experiments on the XP (Cornell University) and BIN (LPI RAS) pulsed power generators are presented. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometries are discussed. Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Results of computer simulation of electron beam propagation from X-pinch to Faraday cup give the limits of measured current for beams having different energy spread. We emphasize the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Different schemes for beam space-charge neutralization are discussed. Longitudinal neutralization is thought to be the most important method because it enables transport of beams with close to the Alfven current. Experimental and computer simulation results on electron beam generation are compared.","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":"74934123","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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