Measurement of (n,γ) reaction cross section of 186W-isotope at neutron energy of 20.02±0.58 MeV

The cross-section of 186W(n,γ)187W reaction has been measured at an average neutron energy of 20.02±0.58 MeV by using activation technique. The 27Al(n,α)24Na and 115In(n,n´)115mIn reactions have been used for absolute neutron flux measurement. Theoretically the reaction cross-sections have been calculated by using the TALYS-1.9 code. The results from the present work and the EXFOR based literature data have been compared with the evaluated data and calculated data from TALYS-1.9 code

Measurement of (n,) reaction cross section of W-186-isotope at neutron energy of 20.02±0.58 MeV

The cross-section of 186W(n,)187W reaction has been measured at an average neutron energy of 20.02±0.58 MeV by using activation technique. The 27Al(n,)24Na and 115In(n,n´)115mIn reactions have been used for absolute neutron flux measurement. Theoretically the reaction cross-sections have been calculated by using the TALYS-1.9 code. The results from the present work and the EXFOR based literature data have been compared with the evaluated data and calculated data from TALYS-1.9 code

Measurement of (n,γ) reaction cross section of 186W-isotope at neutron energy of 20.02±0.58 MeV

392-396The cross-section of 186W(n,γ)187W reaction has been measured at an average neutron energy of 20.02±0.58 MeV by using activation technique. The 27Al(n,α)24Na and 115In(n,n´)115mIn reactions have been used for absolute neutron flux measurement. Theoretically the reaction cross-sections have been calculated by using the TALYS-1.9 code. The results from the present work and the EXFOR based literature data have been compared with the evaluated data and calculated data from TALYS-1.9 code

Defense against network attacks using game theory

As Internet has become ubiquitous, the risk posed by network attacks has greatly increased. Network attacks have been used to achieve a wide gamut of objectives ranging from overloading a website to accessing classified data. Effective defense against such attacks is a critical research area. In this thesis, we demonstrate how game theory can be used to devise effective defense systems. We utilize game theory for defense systems in two scenarios in this thesis. The first scenario is that of the attacker carrying out a Distributed Denial of Service (DDoS) attack. The second scenario involves the attacker possessing the ability to carry out a number of different attacks such as Denial of Service (DoS), Dictionary attacks and Portscans. An important restriction imposed in repeated complete-information games is that each player has complete knowledge of the adversary???s payoffs. This assumption is unrealistic when the adversaries are the defense system and the attacker. We employ a Fictitious-Play approach in order to remove this restriction

Steady state formation of a toroidal electron cloud

A novel scheme of injection and confinement of electrons is reported for the formation of a toroidal electron cloud in the presence of a static toroidal magnetic field. The scheme is based on the use of a combination of externally applied electric field and the self-consistent space charge field for the electron trapping and confinement. The time development of electron cloud potentials measured in the poloidal plane of the torus is presented. A potential well depth exceeding the initial kinetic energy of the electrons is observed, indicating collective effects. The effect of external field on the total charge and capacitance of the electron cloud is also presented

R&D on divertor plasma facing components at the Institute for Plasma Research

This paper is focused on various aspects of the development and testing of water cooled divertor PFCs. Divertor PFCs are mainly designed to absorb the heat and particle fluxes out flowing from the core plasma of fusion devices like ITER. The Divertor and First Wall Technology Development Division at the Institute for Plasma Research (IPR), India, is extensively working on development and testing of divertor plasma facing components (PFCs). Tungsten and graphite macro-brush type test mock-ups were produced using vacuum brazing furnace technique and tungsten monoblock type of test mock-ups were obtained by hot radial pressing (HRP) technique. Heat transfer performance of the developed test mock-ups was tested using high heat flux tests with different heat load conditions as well as the surface temperature monitoring using transient infrared thermography technique. Recently we have established the High Heat Flux Test Facility (HHFTF) at IPR with an electron gun EH300V (M/s Von Ardenne Anlagentechnik GmbH, Germany) having maximum power 200 kW. Two tungsten monoblock type test mock-ups were probed using HHFTF. Both of the test mock-ups successfully sustained 316 thermal cycles during high heat fl ux (HHF) tests. The test mock-ups were non- -destructively tested using infrared thermography before and after the HHF tests. In this note we describe the detailed procedure used for testing macro-brush and monoblock type test mock-ups using in-house transient infrared thermography set-up. An acceptance criteria limit was defined for small scale macro-brush type of mock-ups using DTrefmax value and the surface temperature measured during the HHF tests. It is concluded that the heat transfer behavior of a plasma facing component was checked by the HHF tests followed by transient IR thermography. The acceptance criteria DTrefmax limit for a graphite macro-brush mock-up was found to be ~3centi grade while for a tungsten macro-brush mock-up it was ~5centi grade

Fabrication and characterization of W-Cu functionally graded material by spark plasma sintering process

In this study, seven-layered W/Cu functionally graded material (FGM) (100 W, 80W-20Cu, 60W-40Cu, 50W-50Cu, 40W-60Cu, 20W-80Cu, 100Cu, by wt %) were fabricated by a spark plasma sintering process (SPS). The influences of sintering temperature on microstructure, physical and mechanical properties of the sintered bulk FGM were investigated. Results indicated that the graded structure of the composite densified after the SPS process and interfaces of the layers are clearly visible. All of the layers had a very high relative density, thereby indicating their densification and excellent sintering behavior. SEM and EDX study of the bulk sample crosssection reveal that the graded structure can be retained up to sintering temperature of 1050 degrees C. In addition fine microstructure within each layer with good interface bonding was also observed. Sample sintered at 1050 degrees C exhibited excellent mechanical and physical properties (hardness 239 +/- 5 Hv and relative density of 90.5%). The result demonstrates that SPS is a promising and more suitable process for fabrication of W-Cu functionally graded materials

Fabrication and characterization of tungsten and graphite based PFC for divertor target elements of ITER like tokamak application

The development of the fabrication technology of macro-brush configuration of tungsten (W) and carbon (graphite and CFC) plasma facing components (PFCs) for ITER like tokamak application is presented. The fabrication of qualified joint of PFC is a requirement for fusion tokamak. Vacuum brazing method has been employed for joining of W/CuCrZr and C/CuCrZr. Oxygen free high conductivity (OFHC) copper casting onWtiles was performed followed by machining, polishing and ultrasonic cleaning of the samples prior to vacuum brazing. The W/CuCrZr and graphite/CuCrZr based test mockups were vacuum brazed using silver free alloys. The mechanical shear and tensile strengths were evaluated for the W/CuCrZr and graphite/CuCrZr brazed joint samples. The micro-structural examination of the joints showed smooth interface. The details of fabrication and characterization procedure for macro-brush tungsten and carbon based PFC test mockups are presented

Pre-qualification of brazed plasma facing components of divertor target elements for ITER like tokamak application

Qualification of tungsten (W) and graphite (C) based brazed plasma facing components (PFCs) is an important R&D area in fusion research. Pre-qualification tests for brazed joints between W–CuCrZr and C–CuCrZr using NDT (IR thermography and ultrasonic test) and thermal fatigue test are attempted. Mockups having good quality brazed joints of W and C based PFCs were identified using NDT. Subsequently, thermal fatigue test was performed on the identified mockups. All brazed tiles ofWbased PFC mockups could withstand thermal fatigue test, however, few tiles of C based PFC mockup were found detached. Thermal analyses of mockups are performed using finite element analysis (ANSYS) software to simulate the thermal hydraulic condition with 10MW/m2 uniform heat flux. Details about experimental and computational work are presented here