scholarly journals Two Design Options for Compact Linear Accelerators for High Flux Neutron Source

2021 ◽  
Vol 12 (1) ◽  
pp. 386
Author(s):  
Xiaowen Zhu ◽  
Claude Marchand ◽  
Olivier Piquet ◽  
Michel Desmons
Keyword(s):  
Neutron Source ◽  
Materials Science ◽  
Optimized Design ◽  
Linear Accelerators ◽  
Fundamental Physics ◽  
Design Studies ◽  
Societal Challenges ◽  
Initial Stage ◽  
Design Options ◽  
Better Than

We describe and compare two optimized design options of RF linear accelerators with different resonant frequencies at 162.5 MHz (f0) and 325 MHz (2∙f0). The RFQ + DTL linacs have been designed to provide 13 MeV acceleration to a proton beam for achieving a fast neutron yield of not lower than 1013 n/s via 9Be(p, n)9B reaction in pulsed-mode operation. Our design studies show that none of the two options is better than the other, but that the choice of operating frequency will mainly be determined by the accelerator length and RF cost consideration. This study can serve as a basis for the design of an initial stage of a new high brilliance Compact Accelerator-driven Neutron Source (CANS), aiming to use neutron scattering techniques for studying material properties in fundamental physics, materials science, nuclear energy, as well as for industries and societal challenges.

Development of 200kV ultrahigh-resolution analytical electron microscope

1989 ◽  
Vol 47 ◽  
pp. 108-109
Author(s):  
T. Kaneyama ◽  
M. Naruse ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
Electron Microscope ◽  
Optical Constants ◽  
Materials Science ◽  
Objective Lens ◽  
The Finite Element Method ◽  
Ultrahigh Resolution ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Characteristic Features ◽  
Better Than

In the field of materials science, the importance of the ultrahigh resolution analytical electron microscope (UHRAEM) is increasing. A new UHRAEM which provides a resolution of better than 0.2 nm and allows analysis of a few nm areas has been developed. [Fig. 1 shows the external view] The followings are some characteristic features of the UHRAEM.Objective lens (OL)Two types of OL polepieces (URP for ±10' specimen tilt and ARP for ±30' tilt) have been developed. The optical constants shown in the table on the next page are figures calculated by the finite element method. However, Cs was experimentally confirmed by two methods (namely, Beam Tilt method and Krivanek method) as 0.45 ∼ 0.50 mm for URP and as 0.9 ∼ 1.0 mm for ARP, respectively. Fig. 2 shows an optical diffractogram obtained from a micrograph of amorphous carbon with URP under the Scherzer defocus condition. It demonstrates a resolution of 0.19 nm and a Cs smaller than 0.5 mm.

Optimising the Transfer Alignment of Weapon INS

2003 ◽  
Vol 56 (2) ◽  
pp. 323-335 ◽  
Author(s):  
Paul D. Groves
Keyword(s):  
Inertial Sensor ◽  
Integrated Navigation ◽  
Velocity Measurements ◽  
Transfer Alignment ◽  
Navigation Solution ◽  
Alignment Technique ◽  
Alignment Process ◽  
Using Data ◽  
Design Options ◽  
Better Than

Transfer alignment is the process of initialising and calibrating a weapon INS using data from the host aircraft's navigation system. To determine which transfer alignment technique performs best, different design options have been assessed, supported by simulation work. The dependence of transfer alignment performance on environmental factors, such as manoeuvres, alignment duration, lever arm and inertial sensor quality has also been studied. ‘Rapid’ alignment, using attitude as well as velocity measurements was found to perform better than ‘conventional’ techniques using only velocity. Innovative developments include the estimation of additional acceleration and gyro states and estimation of force dependent relative orientation, which has enabled robust alignment using wing rock manoeuvres, which do not require the pilot to change trajectory. Transfer alignment has been verified in real-time by flight trials on a Tornado aircraft. In addition, techniques have been developed to prevent transients in the aircraft integrated navigation solution following GPS re-acquisition after an outage of several minutes from disrupting the transfer alignment process.

scholarly journals Defect-Tolerant Architectures for Nanoelectronic Crossbar Memories

2007 ◽  
Vol 7 (1) ◽  
pp. 151-167 ◽  
Author(s):  
Dmitri B. Strukov ◽  
Konstantin K. Likharev
Keyword(s):  
Upper Bound ◽  
Memory Cell ◽  
Error Correcting Codes ◽  
Cell Fraction ◽  
Access Time ◽  
Initial Stage ◽  
Order Of Magnitude ◽  
Pitch Ratio ◽  
Better Than

We have calculated the maximum useful bit density that may be achieved by the synergy of bad bit exclusion and advanced (BCH) error correcting codes in prospective crossbar nanoelectronic memories, as a function of defective memory cell fraction. While our calculations are based on a particular ("CMOL") memory topology, with naturally segmented nanowires and an area-distributed nano/CMOS interface, for realistic parameters our results are also applicable to "global" crossbar memories with peripheral interfaces. The results indicate that the crossbar memories with a nano/CMOS pitch ratio close to 1/3 (which is typical for the current, initial stage of the nanoelectronics development) may overcome purely semiconductor memories in useful bit density if the fraction of nanodevice defects (stuck-on-faults) is below ∼15%, even under rather tough, 30 ns upper bound on the total access time. Moreover, as the technology matures, and the pitch ratio approaches an order of magnitude, the crossbar memories may be far superior to the densest semiconductor memories by providing, e.g., a 1 Tbit/cm2 density even for a plausible defect fraction of 2%. These highly encouraging results are much better than those reported in literature earlier, including our own early work, mostly due to more advanced error correcting codes.

scholarly journals DESIGN STUDIES OF PROTON LINEAR ACCELERATORS

1963 ◽  
Author(s):  
D E Young ◽  
R S Christian ◽  
C D Curtis ◽  
T W Edwards ◽  
F J Kriegler ◽  
...  
Keyword(s):  
Linear Accelerators ◽  
Design Studies

Conceptual design studies of GDT-based neutron source

2002 ◽  
Author(s):  
A.A. Ivanov ◽  
E.P. Kruglyakov ◽  
Yu.A. Tsidulko ◽  
V.G. Krasnoperov ◽  
V.V. Korshakov
Keyword(s):  
Conceptual Design ◽  
Neutron Source ◽  
Design Studies

scholarly journals Relativistic Models for a GAIA-Like Astrometry Mission

2000 ◽  
Vol 180 ◽  
pp. 314-319 ◽  
Author(s):  
F. de Felice ◽  
A. Vecchiato ◽  
B. Bucciarelli ◽  
M.G. Lattanzi ◽  
M. Crosta
Keyword(s):  
Reference Frame ◽  
Fundamental Physics ◽  
Accurate Knowledge ◽  
Adopted Model ◽  
Relativistic Approach ◽  
General Relativistic ◽  
Relativistic Models ◽  
Relativistic Parameter ◽  
Relativistic Framework ◽  
Better Than

A non-perturbative general relativistic approach to global astrometry was developed by de Felice et al. (1998) to handle satellite astrometry data in a genuine relativistic framework. In this contribution, the framework above has been further exploited to account for stellar motions and parallax. Because of the relevance that accurate knowledge (to 10−5 or better) of the relativistic parameter γ has to fundamental physics, a Parametrized Post-Newtonian (PPN) model has also been implemented, which allows the direct estimation of γ along with the astrometric parameters. These models have been tested on end-to-end simulations of the mission GAIA. The results show that, within the limitation of the simulation and the assumptions of the adopted model, measurements accurate to 100 μarcsec of large arcs among stars repeated over a few years can be modelled to establish a dense reference frame with a precision of a few tens of μarcseconds. Moreover, our experiments indicate that γ can be estimated to better than 10−6.

scholarly journals The slow combustion of ethane

1930 ◽  
Vol 129 (811) ◽  
pp. 434-457 ◽  
Keyword(s):  
Point Of View ◽  
Decomposition Products ◽  
Chain Reactions ◽  
Hydrocarbon Combustion ◽  
Initial Stage ◽  
Slow Combustion ◽  
Direct Collision ◽  
The Subject ◽  
Direct Incorporation ◽  
Better Than

The slow combustion of ethane was experimentally studied by W. A. Bone and W. E. Stockings more than 25 years ago, and shown to proceed in successive stages of hydroxylation, thus :─ Interest in the subject has recently been revived, chiefly because of the conception of “ chain reactions, “ which (to quote a leading exponent) “ are now generally supposed to occur whenever many molecules are transformed per quantum in a photochemical change, “ and of the supposition that “ in the combustion of hydrocarbons bodies of a peroxide character are formed and that these act as a centres from which chains are propagated.” The mechanism of hydrocarbon combustion was fully discussed in Chapters XXVIII to XXX (pp. 354 to 400) of Bone and Townend’s “Flame and Combustion in Gases “ (1927), especially in relation to H. L. Callendar’s conclusion (from experiments on hexane and higher hydrocarbons) that the initial stage involves the formation of an alkyl peroxide (rather than of an alcohol) “ by the direct incorporation of the oxygen molecules in the hydrocarbon molecule and after direct collision, “ such peroxide subsequently giving rise to aldehydes and water as decomposition products. It was shown that while the two views are not as decomposition products. It was shown that while the two views are not mutually exclusive, and many perhaps even be supplementary, “ hydroxylation “ explains most of the known facts better than “ peroxidation. “ This conclusion was strenghtened by the results of Dr. D. T. A. Townend’s experiments on the partial combustion of methane at high initial pressures which, while quite understandable from the point of view of “ hydroxylation, ” seem incompatible with the idea of a primary peroxide formation. Also, it may be mentioned that in 1928 M. Stanislas Landa, in describing the results of his experimental study of the slow combustion of higher paraffins at 280 to 300°C., reported having isolated alcohols as well as aldehydes from the products in accordance with the “ hydroxylation ” theory.

Advanced Laser Diode Cooling Concepts

2008 ◽  
Vol 1076 ◽  
Author(s):  
Ryan Feeler ◽  
Jeremy Junghans ◽  
Edward Stephens ◽  
Greg Kemner ◽  
Fred Barlow ◽  
...  
Keyword(s):  
Laser Diode ◽  
Thermal Performance ◽  
Materials Science ◽  
State Of The Art ◽  
Power Laser ◽  
Current State ◽  
Laser Diode Arrays ◽  
High Power Laser Diode ◽  
Better Than

ABSTRACTA new, patent-pending method of cooling high-power laser diode arrays has been developed which leverages advances in several areas of materials science and manufacturing. This method utilizes multi-layer ceramic microchannel coolers with small (100's of microns) integral water channels to cool the laser diode bar. This approach is similar to the current state-of-the-art method of cooling laser diode bars with copper microchannel coolers. However, the multi-layer ceramic coolers offer many advantages over the copper coolers, including reliability and manufacturing flexibility. The ceramic coolers do not require the use of deionized water as is mandatory of high-thermal-performance copper coolers.Experimental and modeled data is presented that demonstrates thermal performance equal to or better than copper microchannel coolers that are commercially available. Results of long-term, high-flow tests are also presented to demonstrate the resistance of the ceramic coolers to erosion. The materials selected for these coolers allow for the laser diode bars to be mounted using eutectic AuSn solder. This approach allows for maximum solder bond integrity over the life of the part.

Sign in / Sign up

Export Citation Format

Share Document