A plasma discharge could be an inexpensive and efficient EUV source for microlithography, if issues of brightness, lifetime, debris, repetition rate, and stability can be resolved. A novel discharge EUV source (international patent pending) is being investigated that may offer an economical solution to these issues. The novel EUV discharge seeks to efficiently assemble a hot, dense, uniform, axially stable plasma with magnetic pressure and inductive current drive, employing resonant theta-pinch-type compression of plasma confined in a magnetic mirror. This resonantly compressed mirror plasma (RCMP) source would be continuously driven by a radio frequency oscillator, to obtain an EUV conversion efficiency greater than that of sources in which the plasma is discarded after each radiation burst. An analytic calculation indicates the novel RCMP source could provide 115 W of 13.45 nm radiation in 3.3 mm2sr etendue to an intermediate focus. Numerical modeling of RCMP dynamics has been performed with MHRDR-EUVL, a magnetohydrodynamic (MHD) numerical simulation with atomic and radiation physics. The numerical simulation demonstrates the efficacy of resonant magneto-acoustic heating. An experiment is being developed to test the new concept.
A laser energy deposition model has been incorporated into the MHRDR-EUVL magnetohydrodynamic (MHD) model of EUV sources for microlithography. The model includes inverse-bremsstrahlung absorption, resonance absorption, and reflection of laser radiation from the plasma critical surface. The plasma evolution is simulated in parallel with the MHRDR-EUVL (Magneto-Hydro-Radiative-Dynamic-Research) 2D, three-temperature, MHD computer code. Convenient user-options include simple specification of the full width at half maximum (FWHM) of typical laser profiles, such as Gaussian profiles in space and time. The new laser deposition capability will allow MHRDR-EUVL to calculate the evolution of magnetized laser-produced plasmas. Magnetic fields can reduce the loss of plasma energy caused by plasma expansion and thermal conductivity.
A magnetohydrodynamic (MHD) model of gas discharges has been developed to accelerate the development of compact, intense sources of EUV radiation for microlithography. The model is an MHD numerical simulation with atomic and radiation physics. The plasma evolution is simulated with the MHRDR (Magneto-Hydro-Radiative-Dynamic-Research) 2D, three-temperature, MHD computer code. The MHD results are postrocessed witha code that caluculated the radiation spectrum from Xe ions, including 13.4-nm EUV output, based on a detailed collisional-radiative atomic kinetics model. A variety of gas discharges relevant to microlithography can be modeled with this new tool.
A radiation-magnetohydrodynamic (MHD) model of gas discharges has been developed to accelerate the development of compact, intense sources of EUV radiation for microlithography. The model is an MHD numerical simulation with atomic and radiation physics. The plasma evolution is simulated with the MHRDR (Magneto-Hydro-Radiative-Dynamic-Research) 2D, three-temperature, MHD computer code. The MHD results are postprocessed with a code that calculates the 13.4-nm EUV radiation output from Xe ions, based on a detailed collisional-radiative atomic kinetics model. Modeling of a dense plasma focus discharge, in a Xe-He gas mixture, has been initiated with this new tool.
A multi-channel, fast, hard x-ray diode spectrometer is being developed at the Nevada Terawatt facility. This spectrometer helps facilitate the study of the time evolution of hard x-ray emissions from hot, dense plasma. Each channel in the array can be adjusted individually with shielded view areas, allowing small areas of an x-ray source to be isolated and studied by region. This spatial resolution capability will permit a better understanding of the mechanisms present in hot, dense plasma. Results will be presented of experimental tests, and their interpretation, pertaining to the hard x-ray emissions generated from an x-pinch source in a pulse-power type device.
A new five-channel spectrometer is designed for registration of x-ray spectral line emissions from plasmas with temporal resolution. All channels are independent from each other and include wide variety of dispersing elements (crystals and/or multiplayer mirrors) and detectors (Si-diodes or PCD). Sixth channel is used for device alignments with minimum adjustments can be used as channel for transmission diffraction grating spectrometer or channel for another time resolved detector. The device was used in experiments with different plasma sources in different configurations and showed its reliability and flexibility.
In the study (SPIE 4144, 128 (2000)) we have presented results of the experimental study of a strongly nonuniform spatial distribution of output keV and sub-keV radiation, that transported by different types of glass mono- and policapillary converters from the point x-ray laser plasma and z-pinch plasma sources. In this paper the features of x-ray radiation are analyzed theoretically using the Fresnel-Kirchhoff diffraction theory and the method of images. We show that the wave effects can strongly affect properties of the x-ray capillary optics.
Victor Kantsyrev, Bruno Bauer, Alla Shlyaptseva, Dmitri Fedin, Stephanie Hansen, Radu Presura, Stephan Fuelling, Steve Batie, Andrew Oxner, Harold Faretto, Nick Ouart, Sean Keely, Hank LeBeau, David Chamberlain
The x-ray emission of Ti, Fe, Mo, W and Pt x-pinches are currently bieng studied at the Nevada Terawatt Facility z- pinch machine (0.9-1.0 MA, 100 ns). New x-ray diagnostics for time-resolved spectroscopy and imaging has been developed and used in x-pinch experiments. The total x- ray/EUV yield was more than 10 kJ. The minimum x-ray pulse duration was 1.1 ns (Mo, W, Pt). For Ti, Mo and W pinches x-ray pulses occurred in two or three groups in the narrow time intervals after the start of the current. The most compact emitting region has been observed for a planar-loop Mo x-pinch (the number of hot spots ranging from 1-5 with a minimum size smaller than 30 micrometers at (lambda) <1.5-2 Angstoms). Strong jets were observed (Ti, Fe, Mo) directed toward the discharge axis, perpendicular to the wires. A structure of an x-pinch includes energetic electron beams directed toward the anode and along wires. The total beam energy increases from Ti to W. A pulse of hard x-ray radiation was observed moving upwards along the axial axis with an energy of several hundred keV(Mo). The size of this source was smaller than 1 mm. The measurements of temperature and density of x-pinch plasmas were based on theoretical modeling of K-shell Ti and L-shell Mo spectra (Te=1.5 keV for Ti, 0.8 keV for Mo, Ne up to 2- 3x1022 cm-3 with 1-10% of hot electrons).
A wide variety of x-ray and extreme ultraviolet (EUV) diagnostics are being developed to study z-pinch plasmas at the Nevada Terawatt Facility (NTF) at the University of Nevada, Reno. Time-resolved x-ray/EUV imaging and spectroscopy, polarization spectroscopy, and backlighting will be employed to measure profiles of plasma temperature, density, flow, and charge state and to investigate electron distribution functions and magnetic fields. These diagnostics are used to study the NTF pinch as an x-ray/EUV source for plasma spectroscopy research and to examine the early-time evolution of a current-driven wire, the formation of a plasma sheet from the explosion and merging of wires, etc. The instruments are state-of-the-art applications of glass capillary converters (GCC), multilayer mirrors (MLM), and crystals. Devices include: a novel glass-capillary-based two- dimensional imaging spectrometer, a time-resolved x-ray spectrometer, a 5-channel crystal/MLM spectrometer ('Polychromator') with a transmission grating spectrometer, and two-channel x-ray/EUV polarimeters-spectrometers (to study simultaneously polarization of K- and L-shell radiation). An x-pinch backlighter, yielding point-projection microscopy with ns resolution is under development. X-ray convex-crystal survey spectrometers, and fast filtered x-ray diodes have observed single Ti-, Fe and W-wire z-pinches, and Ti and Fe x- pinches. The NTF x-ray yield and x-ray pulse duration depend sensitively on the wire load. There is evidence of a strong energetic electron beam with a complex spatial structure in x- pinch plasmas. This work is supported by DOE, DOD, SNL, and UNR.
Victor Kantsyrev, Bruno Bauer, Alla Shlyaptseva, Dmitry Fedin, Stephanie Hansen, Radu Presura, Steve Batie, Wade Cline, Harold Faretto, Bruno Le Galloudec, Andrew Oxner, Diana McCrorey, Nick Ouart, Hank LeBeau
Powerful pulsed soft x-ray point sources are being developed, driven by the Zebra z-pinch at the Nevada Terawatt Facility. A wide variety of x-ray and EUV pulses can be generated, depending on the z-pinch load. X-ray and EUV pulses have been produced with duration from 1.5 ns to 40 ns, energy from 30 J to 9 kJ, and effective source size smaller than 100 micrometers . These pulses will be used for the development of plasma diagnostics, for the study of surface physics, and for microscopy.
This research is a continuation of our activity on the development and study of glass-capillary optics devices that started in 1974. We presented new results of the experimental study of a strongly nonuniform spatial distribution of output keV and sub-keV radiation, that transported by different types of glass mono- and polycapillary converters from point x-ray laser plasma and z-pinch plasma sources.
A new multichannel x-ray/extreme ultra violet (EUV) spectrometer is developed for monitoring the time history of x-ray/EUV spectral line intensities from a hot plasma to estimate an electron density and temperature of plasmas. Each independently controlled channel includes a crystal (or multilayer mirror) and a fast x-ray diode. At the same time, an imaging transmission grating is applied to study a spatial distribution of spectral line intensities in a wide spectral region with time gated resolution. The multichannel spectrometer can be applied for measurements of polarization- dependent spectra which will be used for diagnostics of electron beams and measuring a magnetic field in z-pinch plasmas.
The new calibration x-ray/extreme UV facility for plasma diagnostics and bio-medical x-ray microscopy includes a compact solid state high-repetition laser and a universal, computer controlled target vacuum chamber with calibrated x- ray spectrometers, fast x-ray diodes and time-gated pin-hole cameras. Experimental results are presented.
The results of the study and application of the prototype of the novel imaging spectrometer with a glass-capillary multiplexer of a 2D x-ray image of Z-pinch plasma are presented. Output channels are used to obtain an array of time-resolved spectra, which covers the full plasma evolution. A spatial resolution of the spectrometer is about 100-250 micrometers for plasma size up to 5 by 20 mm. A spectral resolution is 700-1000. A time-gated resolution is 1-2 ns.
The Instrumentation Program at Physics Department of the University of Nevada, Reno, USA is based on results of the development and study of one of first glass capillary optics devices in period from 1974 to earlier 90s in USSR/Russia (by V. Kantsyrev, O. Ananyin, Yu. Bykovsky and collaborators). The main direction of our program is the development of several techniques for extreme ultraviolet, soft x-ray and x-ray optical instrumentation, for spectroscopic diagnostics of hot plasmas, spectroscopic studies of interaction of multicharged ion beams with matter, biomedical x-ray microscopy. Our currently-developed instruments include: EUV polarimeter/spectrometer with GCC polarizing and focusing elements; a high resolution, a high-sensitivity EUV and x-ray spectrometer with focusing GCC, that also serves as a high- transmission window for differential vacuum pumping; a prototype of new multiband, two dimensional EUV and x-ray imaging spectrometer for plasma diagnostics; a pinhole camera with GCC using as a hard x-ray filter; a soft x-ray spectrograph with MLM for plasma diagnostics.
In a plasma-electrode Pockels cell (PEPC), plasma discharges serve as transparent electrodes on each side of an electro-optic crystal such as KDP. These plasmas facilitate rapid and uniform charging and discharging of the crystal. We describe PEPC technology deployed on Beamlet and envisioned for the National Ignition Facility. Performance on Beamlet is discussed in detail. We also discuss models which have shed light on PEPC operation. These models describe both the high-voltage sheath that forms near the crystal surface and the characteristics of the bulk plasma column.
Mark Wilke, Andrew Obst, Dan Winske, Michael Jones, Stuart Baker, Joseph Abdallah, Stephen Caldwell, Robert Watt, S. Robert Goldman, Bruno Bauer, Robert Gibson
Colliding Au, CD, and Ti-CR plasmas have been generated by illuminating two opposing foils each with an approximately 100J, 0.5 nsec, 2(omega) Nd-glass laser beam from the Trident laser facility at Los Alamos. The plasmas are being used to study plasma interactions which span the parameter regime from interpenetrating to collisional stagnation. X-ray emission during the laser target interaction and the subsequent collision is used to diagnose the initial plasma conditions and the colliding plasma properties. X-ray instrumentation consists of a 100 ps gated x-ray pinhole imager, a time-integrated bremsstrahlung x-ray spectrograph and a gated x-ray spectrograph used to record isoelectronic spectra from the Ti-Cr plasmas. The imager has obtained multiframe images of the collision and therefore, a measure of the stagnation length which is a function of the ion charge state and density and a strong function of the electon temperature. Other isntrumentation includes a Thomson scattering spectrometer with probe beam, neutron detectors used to monitor the CE coated foil collisions, and an ion spectrometer. We will describe the current status of the experiments and current results with emphasis on the x-ray emission diagnostics. We will also briefly describe the modeling using Lasnex and ISIS, a particle-in-cell code with massless fluid electronics and inter-particle (classical) collisions.
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