K. Gouriet, T. Itina, S. Noël, J. Hermann, M. Sentis, L. Zhigilei
The main objective of this study is to explain the experimental observations. To simulate material ablation, plume formation and its evolution, we developed a combined molecular dynamics (MD) and direct simulation Monte Carlo (DSMC) computational study of laser ablation plume evolution. The first process of the material ablation is described by the MD method. The expansion of the ejected plume is modelled by the DSMC method. To better understand the formation and the evolution of nanoparticles present in the plume, we first used separate MD simulations to analyse the evolution of a cluster in the presence of background gas with different properties (density, temperature). In particular, we examine evaporation and growth reactions of a cluster with different size and initial temperature. As a result of MD calculations, we determinate the influence of the background gas parameters on the nanoparticles. The reactions rates such as evaporation/condensation, which are obtained by MD simulations, are directly transferred to the DSMC part of our combined model. Finally, several calculations performed by using MD-DSMC model demonstrate both plume dynamics and longer-time cluster evolution. Calculations results are compared with experimental findings.
{"title":"Formation of nanoparticles by short and ultra-short laser pulses","authors":"K. Gouriet, T. Itina, S. Noël, J. Hermann, M. Sentis, L. Zhigilei","doi":"10.1117/12.782711","DOIUrl":"https://doi.org/10.1117/12.782711","url":null,"abstract":"The main objective of this study is to explain the experimental observations. To simulate material ablation, plume formation and its evolution, we developed a combined molecular dynamics (MD) and direct simulation Monte Carlo (DSMC) computational study of laser ablation plume evolution. The first process of the material ablation is described by the MD method. The expansion of the ejected plume is modelled by the DSMC method. To better understand the formation and the evolution of nanoparticles present in the plume, we first used separate MD simulations to analyse the evolution of a cluster in the presence of background gas with different properties (density, temperature). In particular, we examine evaporation and growth reactions of a cluster with different size and initial temperature. As a result of MD calculations, we determinate the influence of the background gas parameters on the nanoparticles. The reactions rates such as evaporation/condensation, which are obtained by MD simulations, are directly transferred to the DSMC part of our combined model. Finally, several calculations performed by using MD-DSMC model demonstrate both plume dynamics and longer-time cluster evolution. Calculations results are compared with experimental findings.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122249901","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}
H. Urbassek, Christian Anders, Luis Sandoval, A. Upadhyay
The physical mechanisms and processes underlying the erosion of a surface induced by cluster bombardment or short-pulse laser irradiation are highlighted. When the average energy delivered per atom in the vicinity of the surface becomes comparable to the cohesive energy of the solid, sputtering from a so-called spike may result. Such a spike leads to abundant sputtering (surface erosion) and crater formation. Direct atomization in the region of highest energy deposition, as well as melt flow and gas flow contribute to the erosion. The materials phenomena occurring after ultra-fast laser irradiation of a metal in the ps- or fs-regime are reviewed. With increasing laser fluence, the film melts, voids are formed, the film tears (spallation), and finally fragments to form a multitude of clusters. These processes are universal in the sense that they occur in widely differing materials such as metals or van-der-Waals bonded materials. We investigate a Lennard-Jones solid as well as four different metals (Al, Cu, Ti, W), which vary widely in their cohesive energy, melting temperature, bulk modulus, and crystal structure. When the energy transfer starting the process is scaled to the cohesive energy of the material, the thresholds of these processes adopt similar values. A comparison of the similarities and differences of the mechanisms underlying surface erosion under cluster ion impact and ultrafast laser irradiation will be drawn.
{"title":"Ultrafast laser irradiation vs cluster ion impact: molecular-dynamics comparison of materials processes in highly energized solids","authors":"H. Urbassek, Christian Anders, Luis Sandoval, A. Upadhyay","doi":"10.1117/12.784270","DOIUrl":"https://doi.org/10.1117/12.784270","url":null,"abstract":"The physical mechanisms and processes underlying the erosion of a surface induced by cluster bombardment or short-pulse laser irradiation are highlighted. When the average energy delivered per atom in the vicinity of the surface becomes comparable to the cohesive energy of the solid, sputtering from a so-called spike may result. Such a spike leads to abundant sputtering (surface erosion) and crater formation. Direct atomization in the region of highest energy deposition, as well as melt flow and gas flow contribute to the erosion. The materials phenomena occurring after ultra-fast laser irradiation of a metal in the ps- or fs-regime are reviewed. With increasing laser fluence, the film melts, voids are formed, the film tears (spallation), and finally fragments to form a multitude of clusters. These processes are universal in the sense that they occur in widely differing materials such as metals or van-der-Waals bonded materials. We investigate a Lennard-Jones solid as well as four different metals (Al, Cu, Ti, W), which vary widely in their cohesive energy, melting temperature, bulk modulus, and crystal structure. When the energy transfer starting the process is scaled to the cohesive energy of the material, the thresholds of these processes adopt similar values. A comparison of the similarities and differences of the mechanisms underlying surface erosion under cluster ion impact and ultrafast laser irradiation will be drawn.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127801319","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}
R. Stoian, A. Mermillod-Blondin, C. Mauclair, N. Huot, É. Audouard, I. M. Burakov, N. Bulgakova, Y. P. Meschcheryakov, A. Rosenfeld, A. Husakou, I. Hertel
Ultrafast lasers emerged as promising tools to process refractive index changes in band-gap materials, resulting in waveguiding functions. Positive refractive index changes were often reported in fused silica matrices. However, in glasses characterized by slow electronic relaxation and high thermal expansion, the refractive index change is usually negative, detrimental for waveguide writing. This relates to the formation of hot regions, where, due to thermal expansion, material is quenched in low-density phases. We discuss control mechanisms related to spatio-temporal heat-source design which may be tuned by temporally shaped laser radiation. Programmable temporal tailoring of pulse envelopes triggers transitions from thermal expansion to directional inelastic flow. Consequently, material compaction leads to a positive refractive index change and guiding structures may thus be created. From an application perspective, the structuring quality degrades with the focusing depth due to wavefront distortions generated at the air-dielectric interface inducing spatial energy dispersion. Spatial beam tailoring corrects beam propagation distortion, improving the structuring accuracy. The corrective process is becoming important when laser energy has to be transported without losses at arbitrary depths, with the purpose of triggering mechanisms of positive index change.
{"title":"Designing laser-induced refractive index changes in \"thermal\" glasses","authors":"R. Stoian, A. Mermillod-Blondin, C. Mauclair, N. Huot, É. Audouard, I. M. Burakov, N. Bulgakova, Y. P. Meschcheryakov, A. Rosenfeld, A. Husakou, I. Hertel","doi":"10.1117/12.783449","DOIUrl":"https://doi.org/10.1117/12.783449","url":null,"abstract":"Ultrafast lasers emerged as promising tools to process refractive index changes in band-gap materials, resulting in waveguiding functions. Positive refractive index changes were often reported in fused silica matrices. However, in glasses characterized by slow electronic relaxation and high thermal expansion, the refractive index change is usually negative, detrimental for waveguide writing. This relates to the formation of hot regions, where, due to thermal expansion, material is quenched in low-density phases. We discuss control mechanisms related to spatio-temporal heat-source design which may be tuned by temporally shaped laser radiation. Programmable temporal tailoring of pulse envelopes triggers transitions from thermal expansion to directional inelastic flow. Consequently, material compaction leads to a positive refractive index change and guiding structures may thus be created. From an application perspective, the structuring quality degrades with the focusing depth due to wavefront distortions generated at the air-dielectric interface inducing spatial energy dispersion. Spatial beam tailoring corrects beam propagation distortion, improving the structuring accuracy. The corrective process is becoming important when laser energy has to be transported without losses at arbitrary depths, with the purpose of triggering mechanisms of positive index change.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114986832","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}
Y. Petrov, V. Zhakhovskiĭ, N. Inogamov, S. Ashitkov, V. Khokhlov, Arun K. Upadhyay, M. Agranat, S. Anisimov, K. Nishihara, B. Rethfeld, H. Urbassek
The motion of both Lennard-Jones solids and metals induced by ultrashort laser irradiation near the ablation threshold is investigated by molecular dynamics simulation. The universality of the ablation threshold fluence with respect to the cohesion energy of solids irradiated by femtosecond laser pulses is demonstrated for Lennard-Jones solid and metals simulated by many-body EAM potentials.
{"title":"Equation of state of matter irradiated by short laser pulse and geometry of spalled cupola","authors":"Y. Petrov, V. Zhakhovskiĭ, N. Inogamov, S. Ashitkov, V. Khokhlov, Arun K. Upadhyay, M. Agranat, S. Anisimov, K. Nishihara, B. Rethfeld, H. Urbassek","doi":"10.1117/12.782612","DOIUrl":"https://doi.org/10.1117/12.782612","url":null,"abstract":"The motion of both Lennard-Jones solids and metals induced by ultrashort laser irradiation near the ablation threshold is investigated by molecular dynamics simulation. The universality of the ablation threshold fluence with respect to the cohesion energy of solids irradiated by femtosecond laser pulses is demonstrated for Lennard-Jones solid and metals simulated by many-body EAM potentials.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114992342","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}
M. Baudelet, Myriam G. Boueri, Jin Yu, X. Mao, R. Russo
Laser-Induced Breakdown Spectroscopy (LIBS) has been used since 40 years on typical samples such as metals, alloys, rocks. Detection of organic hazards or analysis of biological compounds under atmospheric pressure with LIBS represents a new challenge. For this purpose, we need better understandings of the physico-chemical properties of the plasma in atmosphere and their influences on the LIBS signal. As a model sample of organic materials, Nylon 6-6 has been studied under nanosecond ablation at different wavelengths (1064 nm and 266 nm) and energies (from 1 to 5 mJ) in order to observe the influence of these parameters. Shadowgraph technique is used to image the plasma at its early stage of expansion (0 to 40 ns). Time-resolved LIBS signal is recorded for longer times (50 ns to 5 μs). In the infrared regime, the expansion of the plume is faster along the laser axis, perpendicular to the sample surface. On the contrary, for UV ablation, the expansion of the plume is quite isotropic. We can also observe different regimes of expansion due to Laser-Supported Detonation Waves (LSDW) above 3 mJ in the UV regime. In particular, these observations provide us ideas to understand the kinetics of the CN emission in the LIBS signal. In the IR regime, a formation of CN due to carbon present in the sample and nitrogen in the air via the reaction 2C + N2 → 2CN can be observed. In the UV regime, the direct ablation of CN bonds is clearly seen but other effects like screening and recombination due to LSDW have also been observed.
{"title":"Correlation between early-stage expansion and spectral emission of a nanosecond laser-induced plasma from organic material","authors":"M. Baudelet, Myriam G. Boueri, Jin Yu, X. Mao, R. Russo","doi":"10.1117/12.785218","DOIUrl":"https://doi.org/10.1117/12.785218","url":null,"abstract":"Laser-Induced Breakdown Spectroscopy (LIBS) has been used since 40 years on typical samples such as metals, alloys, rocks. Detection of organic hazards or analysis of biological compounds under atmospheric pressure with LIBS represents a new challenge. For this purpose, we need better understandings of the physico-chemical properties of the plasma in atmosphere and their influences on the LIBS signal. As a model sample of organic materials, Nylon 6-6 has been studied under nanosecond ablation at different wavelengths (1064 nm and 266 nm) and energies (from 1 to 5 mJ) in order to observe the influence of these parameters. Shadowgraph technique is used to image the plasma at its early stage of expansion (0 to 40 ns). Time-resolved LIBS signal is recorded for longer times (50 ns to 5 μs). In the infrared regime, the expansion of the plume is faster along the laser axis, perpendicular to the sample surface. On the contrary, for UV ablation, the expansion of the plume is quite isotropic. We can also observe different regimes of expansion due to Laser-Supported Detonation Waves (LSDW) above 3 mJ in the UV regime. In particular, these observations provide us ideas to understand the kinetics of the CN emission in the LIBS signal. In the IR regime, a formation of CN due to carbon present in the sample and nitrogen in the air via the reaction 2C + N2 → 2CN can be observed. In the UV regime, the direct ablation of CN bonds is clearly seen but other effects like screening and recombination due to LSDW have also been observed.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"7005 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129427924","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}
B. Rethfeld, S. Linden, L. Englert, M. Wollenhaupt, L. Haag, C. Sarpe-Tudoran, T. Baumert
Transparent solids may absorb energy from a laser beam of sufficient high intensity. Several models are under consideration to describe the evolution of the free-electron density. Some of these models keep track of the energy distribution of the electrons. In this work we compare different models and give rules to estimate which one is applicable. We present the inclusion of a term in the multiple rate equation approach, recently introduced, describing fast recombination processes to exciton states. Moreover, we present experimental results with temporally asymmetric femtosecond laser pulses, impinging on a surface of fused silica. We found different thresholds for surface material modification with respect to an asymetric pulse and its time reversed counterpart. This difference is due to a different time-and-intensity dependence of the main ionization processes, which can be controlled with help of femtosecond shaped laser pulses.
{"title":"Electron generation in laser-irradiated insulators: theoretical descriptions and their application","authors":"B. Rethfeld, S. Linden, L. Englert, M. Wollenhaupt, L. Haag, C. Sarpe-Tudoran, T. Baumert","doi":"10.1117/12.784630","DOIUrl":"https://doi.org/10.1117/12.784630","url":null,"abstract":"Transparent solids may absorb energy from a laser beam of sufficient high intensity. Several models are under consideration to describe the evolution of the free-electron density. Some of these models keep track of the energy distribution of the electrons. In this work we compare different models and give rules to estimate which one is applicable. We present the inclusion of a term in the multiple rate equation approach, recently introduced, describing fast recombination processes to exciton states. Moreover, we present experimental results with temporally asymmetric femtosecond laser pulses, impinging on a surface of fused silica. We found different thresholds for surface material modification with respect to an asymetric pulse and its time reversed counterpart. This difference is due to a different time-and-intensity dependence of the main ionization processes, which can be controlled with help of femtosecond shaped laser pulses.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121451170","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}
This paper describes the status of the stadium-sized National Ignition Facility (NIF), the world's largest laser system and first operational multi-megajoule laser. The 192-beam NIF, located at Lawrence Livermore National Laboratory (LLNL), is 96% complete and scheduled for completion in March 2009. The NIF laser will produce nanosecond laser pulses with energies up to approximately 4 MJ in the infrared (laser wavelength = 1.053-μm) and 2MJ in the ultraviolet (laser wavelength = 0.35-μ m). With these energies NIF will access conditions of pressure and temperature not previously available on earth, allowing it to conduct experiments in support of the nation's national security, energy, and fundamental science goals. First ignition experiments at NIF are scheduled for FY2010. This paper will provide an overview of the NIF laser and the ignition, energy, and fundamental science activities at NIF.
{"title":"Multi-megajoule NIF: ushering in a new era in high energy density science","authors":"E. Moses","doi":"10.1117/12.782724","DOIUrl":"https://doi.org/10.1117/12.782724","url":null,"abstract":"This paper describes the status of the stadium-sized National Ignition Facility (NIF), the world's largest laser system and first operational multi-megajoule laser. The 192-beam NIF, located at Lawrence Livermore National Laboratory (LLNL), is 96% complete and scheduled for completion in March 2009. The NIF laser will produce nanosecond laser pulses with energies up to approximately 4 MJ in the infrared (laser wavelength = 1.053-μm) and 2MJ in the ultraviolet (laser wavelength = 0.35-μ m). With these energies NIF will access conditions of pressure and temperature not previously available on earth, allowing it to conduct experiments in support of the nation's national security, energy, and fundamental science goals. First ignition experiments at NIF are scheduled for FY2010. This paper will provide an overview of the NIF laser and the ignition, energy, and fundamental science activities at NIF.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116237175","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}
One of the many challenges faced by laser propulsion is the long-term performance of the propellant. The chemical changes that can take place at the propellant surface during ablation can greatly modify the in-flight performance characteristics. For stable regimes for propulsion, such chemical action should be minimized. A TEA (Transverse Electrical discharge in gas at Atmospheric pressure) CO2 laser of 10.6 μm wavelength, 300 ns pulse length, and up to 20 J pulse energy was used to ablate several types of polymer targets with a range of observable chemical changes at the surface following ablation. After 10 subsequent shots, the target samples were measured using Attenuated Total Reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy then compared to unablated samples of the same polymer. An analysis of the results was made with an emphasis on laser propulsion applications, with a comparison of the propulsion performance of the targets, specifically regarding the ablated mass per spot area (Δma). Chemical reaction pathways for combustion and vaporization are discussed on the basis of the differences observed in the FTIR spectra, and the consequences for using such materials as laser propulsion propellants are explored.
{"title":"Reflection Fourier transform infrared spectroscopy of polymer targets for CO2 laser ablation","authors":"J. Sinko, C. A. Schlecht","doi":"10.1117/12.782436","DOIUrl":"https://doi.org/10.1117/12.782436","url":null,"abstract":"One of the many challenges faced by laser propulsion is the long-term performance of the propellant. The chemical changes that can take place at the propellant surface during ablation can greatly modify the in-flight performance characteristics. For stable regimes for propulsion, such chemical action should be minimized. A TEA (Transverse Electrical discharge in gas at Atmospheric pressure) CO2 laser of 10.6 μm wavelength, 300 ns pulse length, and up to 20 J pulse energy was used to ablate several types of polymer targets with a range of observable chemical changes at the surface following ablation. After 10 subsequent shots, the target samples were measured using Attenuated Total Reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy then compared to unablated samples of the same polymer. An analysis of the results was made with an emphasis on laser propulsion applications, with a comparison of the propulsion performance of the targets, specifically regarding the ablated mass per spot area (Δma). Chemical reaction pathways for combustion and vaporization are discussed on the basis of the differences observed in the FTIR spectra, and the consequences for using such materials as laser propulsion propellants are explored.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131742117","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}
Y. Ueno, G. Soumagne, T. Suganuma, T. Yabu, M. Moriya, H. Komori, T. Abe, A. Endo, A. Sumitani
We are developing a laser produced plasma light source for high volume manufacturing (HVM) EUV lithography. The light source is based on a high power, high repetition rate CO2 laser (10.6μm) system, a tin (Sn) target and a magnetic ion guiding for Sn treatment. We evaluated the characteristics of Sn debris generated by a CO2 laser produced plasma. Experiments were performed with bulk Sn-plate targets and Mo/Si multilayer mirror samples were used for debris analysis. We observed very thin and uniform Sn layers of nano/sub-nano size debris particles. The layer deposition rate at 120mm from the plasma is, without magnetic field, about 30nm per million shots. The fast Sn ion flux was measured with Faraday cups and the signal decreased by more than 3 orders of magnitude on application of a magnetic field of 1T. The Sn deposition on the Mo/Si multilayer mirror decreased in small magnetic field space by a factor of 5. In a large magnetic field space, the effectiveness of the magnetic guiding of Sn ions is examined by monitoring the fast Sn ions. The ion flux from a Sn plasma was confined along the magnetic axis with a maximum magnetic field of 2T.
{"title":"Magnetic field for efficient exhaustion of CO2 laser-produced Sn plasma in EUV light source","authors":"Y. Ueno, G. Soumagne, T. Suganuma, T. Yabu, M. Moriya, H. Komori, T. Abe, A. Endo, A. Sumitani","doi":"10.1117/12.782475","DOIUrl":"https://doi.org/10.1117/12.782475","url":null,"abstract":"We are developing a laser produced plasma light source for high volume manufacturing (HVM) EUV lithography. The light source is based on a high power, high repetition rate CO2 laser (10.6μm) system, a tin (Sn) target and a magnetic ion guiding for Sn treatment. We evaluated the characteristics of Sn debris generated by a CO2 laser produced plasma. Experiments were performed with bulk Sn-plate targets and Mo/Si multilayer mirror samples were used for debris analysis. We observed very thin and uniform Sn layers of nano/sub-nano size debris particles. The layer deposition rate at 120mm from the plasma is, without magnetic field, about 30nm per million shots. The fast Sn ion flux was measured with Faraday cups and the signal decreased by more than 3 orders of magnitude on application of a magnetic field of 1T. The Sn deposition on the Mo/Si multilayer mirror decreased in small magnetic field space by a factor of 5. In a large magnetic field space, the effectiveness of the magnetic guiding of Sn ions is examined by monitoring the fast Sn ions. The ion flux from a Sn plasma was confined along the magnetic axis with a maximum magnetic field of 2T.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133307512","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 concept of power-scalable, high beam-quality diode pumped alkali lasers was introduced in 2003 [Krupke, US Patent No. 6,643,311; Opt. Letters, 28, 2336 (2003)]. Since then several laboratory DPAL devices have been reported on, confirming many of the spectroscopic, kinetic, and laser characteristics projected from literature data. This talk will present an overview of the DPAL concept, summarize key relevant properties of the cesium, rubidium, and potassium alkali vapor gain media so-far examined, outline power scaling considerations, and highlight results of published DPAL laboratory experiments.
{"title":"Diode pumped alkali lasers (DPALs): an overview","authors":"W. Krupke","doi":"10.1117/12.782466","DOIUrl":"https://doi.org/10.1117/12.782466","url":null,"abstract":"The concept of power-scalable, high beam-quality diode pumped alkali lasers was introduced in 2003 [Krupke, US Patent No. 6,643,311; Opt. Letters, 28, 2336 (2003)]. Since then several laboratory DPAL devices have been reported on, confirming many of the spectroscopic, kinetic, and laser characteristics projected from literature data. This talk will present an overview of the DPAL concept, summarize key relevant properties of the cesium, rubidium, and potassium alkali vapor gain media so-far examined, outline power scaling considerations, and highlight results of published DPAL laboratory experiments.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121214617","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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