Download or read book On the Absolute Calibration of a DT Fusion Neutron Yield Diagnostic written by and published by . This book was released on 2011 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measuring the Absolute DT Neutron Yield Using the Magnetic Recoil Spectrometer at OMEGA and the NIF written by and published by . This book was released on 2012 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Magnetic Recoil Spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion (ICF) implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.
Download or read book Calibration Issues for Neutron Diagnostics written by and published by . This book was released on 1997 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of diagnostic systems are limited by their weakest constituents, including their calibration issues. Neutron diagnostics are notorious for problems encountered while determining their absolute calibrations, due mainly to the nature of the neutron transport problem. In order to facilitate the determination of an accurate and precise calibration, the diagnostic design should be such as to minimize the scattered neutron flux. ITER will use a comprehensive set of neutron diagnostics--comprising radial and vertical neutron cameras, neutron spectrometers, a neutron activation system and internal and external fission chambers--to provide accurate measurements of fusion power and power densities as a function of time. The calibration of such an important diagnostic system merits careful consideration. Some thoughts have already been given to this subject during the conceptual design phase in relation to the time-integrated neutron activation and time-dependent neutron yield monitors. However, no overall calibration strategy has been worked out so far. This paper represents a first attempt to address this vital issue. Experience gained from present large tokamaks (JET, TFTR and JT60U) and proposals for ITER are reviewed. The need to use a 14-MeV neutron generator as opposed to radioactive sources for in-situ calibration of D-T diagnostics will be stressed. It is clear that the overall absolute determination of fusion power will have to rely on a combination of nuclear measuring techniques, for which the provision of accurate and independent calibrations will constitute an ongoing process as ITER moves from one phase of operation to the next.
Download or read book An Improved Method for Measuring the Absolute DD Neutron Yield and Calibrating Neutron Time of flight Detectors in Inertial Confinement Fusion Experiments written by Caleb Joseph Waugh and published by . This book was released on 2014 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the establishment of nuclear physics in the early 1900's and the development of the hydrogen bomb in the 1950's, inertial confinement fusion (ICF) has been an important field in physics. Funded largely though the U.S. National Nuclear Security Agency (NNSA), the Laboratory for Laser Energetics (LLE), Sandia National Laboratories (SNL) and Lawrence Livermore National Laboratory (LLNL) have advanced ICF as a platform for stockpile stewardship and weapons physics, but also have contributed to basic science in high energy density regimes and for pursuing fusion an energy source. One of the primary goals of the ICF research program is to produce a thermonuclear burn in an ICF capsule where the power balance of the reaction is net positive. This criterion is often referred to as ignition. One of the most common metrics for gauging progress towards ignition in an ICF implosion is the ITFX parameter (similar to the Lawson Criterion) and is primarily a function of the implosion areal density (pR) and fusion yield. An ITFX value greater than one indicates net energy production. In deuterium/tritium fuel mixtures the yield is determined by measuring the reactant 14.0 MeV neutrons. Subsequently, the ability to obtain highly accurate absolute neutron yield measurements is vital to determining the ITFX and hence progress toward ignition. Although ignition implosions all use deuterium/tritium fuel mixes, other capsule fuel mixes such as pure deuterium and deuterium/helium 3 are also used to improve understanding of capsule performance. At the LLE and LLNL, neutron time-of-flight (nTOF) detectors routinely measure the absolute neutron yield from laser-driven ICF implosions. Although originally calibrated through a series of cross-calibrations with indium and copper neutron activation systems, an alternative method has been developed for measuring the DDn yield that provides a more accurate calibration by directly calibrating nTOF in situ to CR-39 range filter (RF) proton detectors. A neutron yield can be inferred from the CR-39 RF proton measurement since the DD proton and DD neutron branching ratio is well characterized and close to unity. By obtaining highly accurate DDp yields from a series of exploding pusher campaigns on OMEGA, an excellent absolute DDn yield measurement was obtained and used to calibrate the 3m nTOF detector. Data obtained suggest the existing OMEGA nTOF calibration coefficient to be low by 9.0 1.5 % based on the inferred CR-39 DD neutron yield. In addition, comparison across multiple exploding pusher campaigns indicate that significant reduction in charged particle flux anisotropies can be achieved on shots where capsule bang time occurs significantly (on the order of 500ps) after the end of the laser pulse. This is important since the main source of error in the RF DDp yield measurement is due to particle flux anisotropies. Results indicate that the CR-39 RF/nTOF in situ calibration method can serve as a valuable platform for measuring the DDn yield from ICF implosions and for calibrating and reducing the uncertainty of calibration coefficients of nTOF detector systems on OMEGA and other larger facilities such as the National Ignition Facility (NIF).
Download or read book Diagnostics for Experimental Thermonuclear Fusion Reactors 2 written by Peter E. Stott and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 615 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book of proceedings collects the papers presented at the workshop on "Diagnostics for Experimental Fusion Reactors" held at Villa Monastero, Varenna (Italy) September 4-12, 1997. This workshop was the seventh organized by the International School of Plasma Physics "Piero Caldirola" on the topic of plasma diagnostics and the second devoted to the diagnostic studies for the International Thermonuclear Experimental Reactor (ITER). The proceedings of the first workshop on ITER diagnostics were published by Plenum Press in 1996 with the title "Diagnostics for Experimental Thermonuclear Fusion Reactors". While many of the ideas and studies reported in the first workshop remain valid, there has been sub stantial progress in the design and specification of many diagnostics for ITER. This moti vated a second workshop on this topic and the publication of a new book of proceedings. ITER is a joint venture between Europe, Japan, Russia and USA in the field of con trolled thermonuclear fusion research. The present aim of ITER is to design an experimental fusion reactor that can demonstrate ignition and sustained burn in a magnetically confined plasma. To achieve this goal, a wide range of plasma parameters will have to be measured reliably. It is also anticipated that diagnostics will be used much more extensively as input to control systems on ITER than on present fusion devices and this will require increased relia bility and long-term stability.
Download or read book Absolute Calibration of the Neutron Yield Measurement on JT 60 Upgrade written by C. W. (and others). Barnes and published by . This book was released on 1991 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diagnostics for Experimental Thermonuclear Fusion Reactors written by Giuseppe Gorini and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book of proceedings collects the papers presented at the Workshop on Diagnostics for ITER, held at Villa Monastero, Varenna (Italy), from August 28 to September 1, 1995. The Workshop was organised by the International School of Plasma Physics "Piero Caldirola. " Established in 1971, the ISPP has organised over fifty advanced courses and workshops on topics mainly related to plasma physics. In particular, courses and workshops on plasma diagnostics (previously held in 1975, 1978, 1982, 1986, and 1991) can be considered milestones in the history of this institution. Looking back at the proceedings of the previous meetings in Varenna, one can appreciate the rapid progress in the field of plasma diagnostics over the past 20 years. The 1995 workshop was co-organised by the Istituto di Fisica del Plasma of the National Research Council (CNR). In contrast to previous Varenna meetings on diagnostics, which have covered diagnostics in present-day tokamaks and which have had a substantial tutorial component, the 1995 workshop concentrated specifically on the problems and challenges of ITER diagnostics. ITER (the International Thennonuclear Experimental Reactor, a joint venture of Europe, Japan, Russia, and the United States, presently under design) will need to measure a wide range of plasma parameters in order to reach and sustain high levels of fusion power. A list of the measurement requirements together with the parameter ranges, target measurement resolutions, and accuracies provides the starting point for selecting a list of candidate diagnostic systems.
Download or read book Absolute Calibration of a Ra Be Neutron Source written by Robert Lee Walker and published by . This book was released on 1946 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Method for in Situ Absolute DD Yield Calibration of Neutron Time of flight Detectors on OMEGA Using CR 39 based Proton Detectors written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.
Download or read book Calculations to Support JET Neutron Yield Calibration written by Snoj. L. and published by . This book was released on 2011* with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Neutron yield measurements are the basis for the determination of the absolute fusion reaction rate and the operational monitoring with respect to the neutron budget during any campaign for JET, the Joint European Torus. After the 2010 changes of the JET plasma-facing materials (Carbon wall to ITER-Like Wall transition), confirmation of the neutron yield calibration will be ensured by direct measurements using a calibrated 252Cf neutron source deployed inside the JET vacuum vessel. In order to thoroughly understand the transport of neutrons from the vacuum vessel to the fission chamber detectors mounted outside the vessel on the transformer limbs and thus to computationally support the JET neutron calibrations project, we developed a simple but quick-running computational model of the JET tokamak for performing Monte Carlo neutron transport calculations."--Abstract.
Download or read book Absolute Calibration of TFTR Neutron Detectors for D T Plasma Operation written by Cris W. Barnes and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Absolute Measurement of DT Neutron Yield on the National Ignition Facility written by and published by . This book was released on 2011 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Absolute Calibration of TFTR Neutron Detectors for D T Plasma Operation written by Cris W. Barnes and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Preliminary Calibration of Radial Neutron Time Of Flight Detectors on a Dense Plasma Focus written by Jacquelynne Vaughan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron time-of-flight (nTOF) detectors are commonly used for fast neutron detection on nuclear fusion plasma experiments in high energy density physics. The 4.6-kJ dense plasma focus (DPF) at UC San Diego can generate neutron yields of up to ~108. Two nTOF detectors radially situated at 1.3 m from the DPF are each composed of an EJ-204 plastic scintillator and an Hamamatsu R7724 photomultiplier tube. Several hundred experimental shots have been taken over the course of four different anode types. Of those, 203 shots with neutron data were selected to calibrate both nTOF detectors. A Be-activation detector generates absolute neutron yield data and has a lower detection limit of 1.1·106 neutrons. The latter is used to calibrate the signal areas in the nTOF data, and directly correlate those signal areas with the number of neutrons incident on the detector at its radius from the DPF. This preliminary analysis finds that the two nTOF detectors have approximate efficiencies of 8100 and 1700 photons per DD neutron, respectively. Further analysis can improve the correlation as well as investigate the cross-calibration between the two nTOF detectors more thoroughly.
Download or read book Calibration Methods for Neutron Diagnostics at Omega DOE NLUF Final Report written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of Calibration Methods for Neutron Diagnostics at Omega is still underway. The data shown here is a compilation of measurements taken at Omega during the time of the grant. The data set has been updated with additional information taken this year. The neutron yield from an ICF event was determined by measuring the activity of an aluminum sample activated by target-produced DT neutrons. The radioactive nuclei[sup 24]Na and[sup 27]Mg, which were produced via the[sup 27]Al(n, [alpha])[sup 24]Na and[sup 27]Al(n, p)[sup 27]Mg direct reactions, beta decay to excited states of[sup 24]Mg and[sup 27]Al respectively. These excited states then emitted gamma rays as the nuclei de-excite to their respective ground states. The gamma rays are detected and counted. From their numbers the neutron yield is determined.
Download or read book Numerical Simulations of In situ Neutron Detector Calibration Experiments on the Tokamak Fusion Test Reactor written by and published by . This book was released on 1990 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate determinations of fusion neutron yields on the TFTR require that the neutron detectors be absolutely calibrated in-situ, using neutron sources of known strengths. For such calibrations, numerical simulations of neutron transport can be powerful tools in the design of experiments and the study of measurement results. On the TFTR, numerical calibration experiments' have been frequently used to complement actual detector calibrations. We present calculational approaches and transport models used in these numerical simulations, and summarize the results from simulating the calibration of 235U fission detectors carried out in December 1988. 12 refs., 9 figs., 6 tabs.
Download or read book DD Neutron Yield Measurements on Z Using Lead Probes written by and published by . This book was released on 2000 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of inertial confinement fusion (ICF) capsule experiments were run on the Z machine at Sandia's Pulsed Power directorate. These experiments were designed specifically to implode a 2 mm diameter hollow plastic capsule filled with deuterium gas. The implosion of the capsule should raise the temperature (kinetic energy) of the deuterium gas ions, which will interact with each other and produce 2.45 MeV fusion neutrons. The author is reporting on one diagnostic technique used to measure the yield of these fusion neutrons. The technique chosen to measure the DD neutron yield is the use of lead (Pb) probe detectors. The assignment was to calibrate two detectors for the 2.50-MeV neutrons produced by the deuterium-deuterium fusion reactions on Z. The author introduces ICF, and then describes the theory, the design, and the calibration of the lead probe. Finally, she presents the results of the ICF experiments and explain the difficulties inherent in analyzing the data.
