ABSTRACT Diagnostic electrical services provide the electrical infrastructure to serve diagnostic... more ABSTRACT Diagnostic electrical services provide the electrical infrastructure to serve diagnostic components installed on the ITER tokamak. This infrastructure is composed of cables, connectors, cable tails, looms, conduits and feedthroughs. The diagnostic services offer as well a shelter for various instrumentations – vacuum vessel (VV), blanket and divertor. The diagnostic sensors are located on the inner and outer VV wall, on blanket shield modules, divertor cassettes and in port plugs. They require electrical cabling to extract the measurement and, in some cases, to supply electrical power to the sensors. These cables run from the sensors to feedthroughs on the VV and the port interspace or cryostat. The design and integration of all components that are part of diagnostic electrical services is an important engineering activity that is being challenged by the multiple requirements and constraints which have to be satisfied while at the same time delivering the required diagnostic performance. The positioning of the components must correlate not only with their functional specifications but also with the design of the major ITER components. This is a particular challenge because not all systems have reached the same level of design maturity. This paper outlines the engineering challenges of ITER diagnostics electrical services. The environmental conditions inside the VV will have an important impact. Leading risks to these components include poor electrical contact at connectors, the effects of exposure to nuclear irradiation, such as material transmutation, heating, and generation of spurious electrical signals etc., failure due to electromagnetic forces and electrical interference due to the noisy environment. Last but not least are the challenges for confinement and vacuum requirements set up on electrical feedthroughs. It will focus as well on the design and structural assessment of all components, and their requirements. Besides the integration limitations, the loads are the main design driver.
Presently many of the experimental systems are designed using Computer Aided Design (CAD) softwar... more Presently many of the experimental systems are designed using Computer Aided Design (CAD) software. But the physics and mathematical modelling with traditional computational codes require geometrical information in conventional manner. Extracting the geometrical information from a complicated CAD model is non-trivial, tedious and time consuming process. A computer code has been developed to reconstruct the geometrical information from Computer Aided Design (CAD) models. CAD models generally occupy the geometric class called Boundary representation (Brep), thus the present code converts boundary representations (Brep) into Constructive Solid Geometries (CSG). The present code extracts geometric information from CAD models and converts it to primitive mathematical form which can then be readily used in other codes like fluid codes, radiation transport codes. This code can also be used for engineering applications like geometric recognition. The present code acts as a bridge between the modern CAD representation and primitive geometrical representation required by physicists or mathematicians. The code can be made available freely for academic use upon request.
In order to study the neutronics of fusion reactor blankets, a program is underway at the Institu... more In order to study the neutronics of fusion reactor blankets, a program is underway at the Institute for Plasma Research (IPR) using 14-MeV neutron source. An accelerator based neutron generator is under development in which 1 mA deuterium beam is accelerated up to 300 keV. It then impinges on a 20 Curie tritiated target and would produce 14-MeV neutrons. The expected neutron yield is ~ 1011 n/s. This neutron generator consists of an ECR ion source, beam extraction system, acceleration column, vacuum system, beam steerer, beam profile monitor, faraday cup, high voltage power supply and isolation transformer. The extraction system which consist of puller electrode and focusing electrodes, were designed using SIMION-8.0 code. This paper describes the modeling of extraction system. The result of ion beam current measurement as function of the focusing voltage is also given.
The proposed intense 14 MeV neutron source at IPR is accelerator based using the T(d,n) reaction.... more The proposed intense 14 MeV neutron source at IPR is accelerator based using the T(d,n) reaction. This facility will be indigenously built and used for the fusion Neutronics studies. Deuterium ions will be accelerated up to 300 keV in an electrostatic acceleration column delivering a maximum beam current of 20 mA. The beam will be made to impinge a water cooled, rotating tritium target. The expected neutron yield will be ~1012 neutron per second. This paper describes the preliminary design of the neutron generator and the MCNP model results of the shielding calculations. The calculation of dose rate has been carried out for the optimum thickness of concrete shield.
In a Burning Plasma Experiment (BPE) like ITER, fusion power is continuously monitored by measuri... more In a Burning Plasma Experiment (BPE) like ITER, fusion power is continuously monitored by measuring the neutron flux Neutron activation method using the conventional solid metal foils results in poor time resolution. The activation of water by 14-MeV neutrons where 16O (n, p) N16 nuclear reaction takes place is the most promising candidate for this purpose. The short half-life of N16 radio nuclide produced in this reaction (T1/2 ~7.13sec) and the threshold energy being high enough (~ 10.4 MeV) makes it a preferred technique. In order to check the feasibility of this technique, an experimental set-up was designed. The experimental set-up consisted of a water pipeline running between the neutron generator and a detector. The detector was a fully shielded and collimated NaI(Tl) spectrometer. The water column was irradiated with the 14-MeV neutrons produced in a sealed neutron generator. Water when irradiated with 14-MeV neutrons produces gamma photons of energies 6.128 MeV (67.06%) and...
The Radial Neutron Camera (RNC) is a multichannel neutron collimator intended to characterize fus... more The Radial Neutron Camera (RNC) is a multichannel neutron collimator intended to characterize fusion plasma neutron sources. The ITER RNC diagnostic will measure the time-resolved neutron emission profile, providing the evaluation of the fusion power density and α-source emissivity profile, ion temperature profile and others parameters. Knowledge of the spatial and energy distribution of the fast ions is also important for optimizing fusion burn control, Alfvén eigenmode control, and the auxiliary fusion plasma heating systems like Neutral Beam and ICRF. The RNC consists of two fan-shaped arrays of collimators that view the plasma through a vertical slot in the blanket shield module of Equatorial Port plug#1. The sight lines intersect at a common aperture defined by the port plug and penetrate the vacuum vessel through stainless steel windows, cryostat, and biological shield. Each flight tube culminates in a set of neutron detectors chosen to provide the required range of sensitivit...
ITER will have a set of 45 diagnostics to ensure controlled operation. Many of them are integrate... more ITER will have a set of 45 diagnostics to ensure controlled operation. Many of them are integrated in the ITER ports. This paper addresses the integration process of the diagnostic systems and the approach taken to enable coordinated progress. An overview of the Port Integration hardware introduces the various structures needed for hosting tenant systems inside ITER diagnostics ports. The responsibilities of the different parties involved (ITER Organization and the Domestic Agencies) are outlined. The main challenges for diagnostic port integration engineering are summarised. The plan for a common approach to design and manufacture of the supporting structures, in particular the Port Plug is detailed. A coordinated design including common components and a common approach for neutronic analyses is proposed. One particular port, the equatorial port 11, is used to illustrate the approach.
In-Port detectors: Two types of candidate neutron detectors were evaluated : fission chamber (FC)... more In-Port detectors: Two types of candidate neutron detectors were evaluated : fission chamber (FC) with 238 U as fissile material and diamond detector.
ITER is an experimental nuclear reactor, aiming to demonstrate the feasibility of nuclear fusion ... more ITER is an experimental nuclear reactor, aiming to demonstrate the feasibility of nuclear fusion realization in order to use it as a new source of energy. ITER is a plasma device (tokamak type) which will be equipped with a set of plasma diagnostic tools to satisfy three key requirements: machine protection, plasma control and physics studies by measuring about 100 different parameters. ITER diagnostic equipment is integrated in several ports at upper, equatorial and divertor levels as well internally in many vacuum vessel locations. The Diagnostic Systems will be procured from ITER Members (Japan,
ABSTRACT –The radionuclide 55Fe (t1/2 5 2.73 years) is one of the radionuclides produced in large... more ABSTRACT –The radionuclide 55Fe (t1/2 5 2.73 years) is one of the radionuclides produced in large quantities inside a fusion reactor. The excitation function of the (n,p) reaction from threshold to 20 MeV and proton emission spectra from the 55Fe target at 14-MeV neutron energy are calculated using optimized input parameters in the nuclear reaction modular codes EMPIRE-3.1 and TALYS-1.4. The codes account for the major nuclear reaction mechanisms, including direct, preequilibrium, and compound nucleus contributions. The present results of 55Fe(n,p)55Mn are compared with the existing evaluated nuclear data libraries ROSFOND-2010, JEFF-3.1, and EAF-2010 along with systematics around 14-MeV neutron energy. The prediction accuracy of the present calculation is considered to satisfy the requirementfor fusion reactor applications. The theoretical nuclear model calculations with a reliable parameter set up to 20 MeV are recommended to estimate the cross section of radionuclides or unstable targets in the mass region A * 50 to 60. The present work is an important step to study the cross section of the 55Fe(n,p)55Mn reaction by a surrogate method.
Fusion power output of ITER is measured by a group of neutron flux monitors combined with a neutr... more Fusion power output of ITER is measured by a group of neutron flux monitors combined with a neutron activation system and neutron profile monitors. These systems should be absolutely calibrated by use of DD/DT generators moving inside the ITER vacuum vessel (in-situ calibration). Each neutron monitor has a limited measurement range of emission rate, but the ranges are connected by cross-calibration using the ITER plasma with at least one decade overlapping. The over all dynamic range covered by the group of neutron flux monitors is 10 14 n/sec to 10 21 n/sec. Effects of vertical/radial movement of plasma on the measurement accuracy were reviewed. It was found that cross-calibration using specially planned jog shots, and a vertical neutron camera is important to minimize the inaccuracy caused by the plasma movement.
Flux measurement of an accelerator based D-T neutron generator was achieved by the activation tec... more Flux measurement of an accelerator based D-T neutron generator was achieved by the activation technique. The neutron generator can produce maximum neutron yield of 1.9x 10 10 n1sec at the Tritium-target For the measurement of 14 MeV neutron Dux, 63Cu(n, 2n) 62 Cu and 27AI(n, p)27Mg reactions are most suitable because of their higher threshold energies 11.03 MeV and 3.25 MeV respectively. Measurement ofy-ray activities from 62CU and 27Mg is used to measure 14 MeV neutron Dux. NaI(TI) scintillation and High Purity Germanium (HPGe) detectors were used for the y-radiation measurement from 62CU and 27Mg respectively. In this paper the 14 MeV neutron Dux measurement by 63CU and 27AI activation is discussed. The method could also serve as a diagnostics tool for measurement of high-energy neutron Dux.
Neutron field parameter measurements on the JET tokamak by means of super-heated fluid detectors ... more Neutron field parameter measurements on the JET tokamak by means of super-heated fluid detectors Rev. Sci. Instrum. 83, 10E124 (2012) HELIOS: A helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR Rev. Sci. Instrum. 83, 10D722 δf Monte Carlo calculation of neoclassical transport in perturbed tokamaks Phys. Plasmas 19, 082503 Active spectroscopic measurements of the bulk deuterium properties in the DIII-D tokamak (invited) Rev. Sci. Instrum. 83, 10D529 A novel local equilibrium model for shaped tokamak plasmas Phys. Plasmas 19, 072520 Additional information on Rev. Sci. Instrum.
ABSTRACT Diagnostic electrical services provide the electrical infrastructure to serve diagnostic... more ABSTRACT Diagnostic electrical services provide the electrical infrastructure to serve diagnostic components installed on the ITER tokamak. This infrastructure is composed of cables, connectors, cable tails, looms, conduits and feedthroughs. The diagnostic services offer as well a shelter for various instrumentations – vacuum vessel (VV), blanket and divertor. The diagnostic sensors are located on the inner and outer VV wall, on blanket shield modules, divertor cassettes and in port plugs. They require electrical cabling to extract the measurement and, in some cases, to supply electrical power to the sensors. These cables run from the sensors to feedthroughs on the VV and the port interspace or cryostat. The design and integration of all components that are part of diagnostic electrical services is an important engineering activity that is being challenged by the multiple requirements and constraints which have to be satisfied while at the same time delivering the required diagnostic performance. The positioning of the components must correlate not only with their functional specifications but also with the design of the major ITER components. This is a particular challenge because not all systems have reached the same level of design maturity. This paper outlines the engineering challenges of ITER diagnostics electrical services. The environmental conditions inside the VV will have an important impact. Leading risks to these components include poor electrical contact at connectors, the effects of exposure to nuclear irradiation, such as material transmutation, heating, and generation of spurious electrical signals etc., failure due to electromagnetic forces and electrical interference due to the noisy environment. Last but not least are the challenges for confinement and vacuum requirements set up on electrical feedthroughs. It will focus as well on the design and structural assessment of all components, and their requirements. Besides the integration limitations, the loads are the main design driver.
Presently many of the experimental systems are designed using Computer Aided Design (CAD) softwar... more Presently many of the experimental systems are designed using Computer Aided Design (CAD) software. But the physics and mathematical modelling with traditional computational codes require geometrical information in conventional manner. Extracting the geometrical information from a complicated CAD model is non-trivial, tedious and time consuming process. A computer code has been developed to reconstruct the geometrical information from Computer Aided Design (CAD) models. CAD models generally occupy the geometric class called Boundary representation (Brep), thus the present code converts boundary representations (Brep) into Constructive Solid Geometries (CSG). The present code extracts geometric information from CAD models and converts it to primitive mathematical form which can then be readily used in other codes like fluid codes, radiation transport codes. This code can also be used for engineering applications like geometric recognition. The present code acts as a bridge between the modern CAD representation and primitive geometrical representation required by physicists or mathematicians. The code can be made available freely for academic use upon request.
In order to study the neutronics of fusion reactor blankets, a program is underway at the Institu... more In order to study the neutronics of fusion reactor blankets, a program is underway at the Institute for Plasma Research (IPR) using 14-MeV neutron source. An accelerator based neutron generator is under development in which 1 mA deuterium beam is accelerated up to 300 keV. It then impinges on a 20 Curie tritiated target and would produce 14-MeV neutrons. The expected neutron yield is ~ 1011 n/s. This neutron generator consists of an ECR ion source, beam extraction system, acceleration column, vacuum system, beam steerer, beam profile monitor, faraday cup, high voltage power supply and isolation transformer. The extraction system which consist of puller electrode and focusing electrodes, were designed using SIMION-8.0 code. This paper describes the modeling of extraction system. The result of ion beam current measurement as function of the focusing voltage is also given.
The proposed intense 14 MeV neutron source at IPR is accelerator based using the T(d,n) reaction.... more The proposed intense 14 MeV neutron source at IPR is accelerator based using the T(d,n) reaction. This facility will be indigenously built and used for the fusion Neutronics studies. Deuterium ions will be accelerated up to 300 keV in an electrostatic acceleration column delivering a maximum beam current of 20 mA. The beam will be made to impinge a water cooled, rotating tritium target. The expected neutron yield will be ~1012 neutron per second. This paper describes the preliminary design of the neutron generator and the MCNP model results of the shielding calculations. The calculation of dose rate has been carried out for the optimum thickness of concrete shield.
In a Burning Plasma Experiment (BPE) like ITER, fusion power is continuously monitored by measuri... more In a Burning Plasma Experiment (BPE) like ITER, fusion power is continuously monitored by measuring the neutron flux Neutron activation method using the conventional solid metal foils results in poor time resolution. The activation of water by 14-MeV neutrons where 16O (n, p) N16 nuclear reaction takes place is the most promising candidate for this purpose. The short half-life of N16 radio nuclide produced in this reaction (T1/2 ~7.13sec) and the threshold energy being high enough (~ 10.4 MeV) makes it a preferred technique. In order to check the feasibility of this technique, an experimental set-up was designed. The experimental set-up consisted of a water pipeline running between the neutron generator and a detector. The detector was a fully shielded and collimated NaI(Tl) spectrometer. The water column was irradiated with the 14-MeV neutrons produced in a sealed neutron generator. Water when irradiated with 14-MeV neutrons produces gamma photons of energies 6.128 MeV (67.06%) and...
The Radial Neutron Camera (RNC) is a multichannel neutron collimator intended to characterize fus... more The Radial Neutron Camera (RNC) is a multichannel neutron collimator intended to characterize fusion plasma neutron sources. The ITER RNC diagnostic will measure the time-resolved neutron emission profile, providing the evaluation of the fusion power density and α-source emissivity profile, ion temperature profile and others parameters. Knowledge of the spatial and energy distribution of the fast ions is also important for optimizing fusion burn control, Alfvén eigenmode control, and the auxiliary fusion plasma heating systems like Neutral Beam and ICRF. The RNC consists of two fan-shaped arrays of collimators that view the plasma through a vertical slot in the blanket shield module of Equatorial Port plug#1. The sight lines intersect at a common aperture defined by the port plug and penetrate the vacuum vessel through stainless steel windows, cryostat, and biological shield. Each flight tube culminates in a set of neutron detectors chosen to provide the required range of sensitivit...
ITER will have a set of 45 diagnostics to ensure controlled operation. Many of them are integrate... more ITER will have a set of 45 diagnostics to ensure controlled operation. Many of them are integrated in the ITER ports. This paper addresses the integration process of the diagnostic systems and the approach taken to enable coordinated progress. An overview of the Port Integration hardware introduces the various structures needed for hosting tenant systems inside ITER diagnostics ports. The responsibilities of the different parties involved (ITER Organization and the Domestic Agencies) are outlined. The main challenges for diagnostic port integration engineering are summarised. The plan for a common approach to design and manufacture of the supporting structures, in particular the Port Plug is detailed. A coordinated design including common components and a common approach for neutronic analyses is proposed. One particular port, the equatorial port 11, is used to illustrate the approach.
In-Port detectors: Two types of candidate neutron detectors were evaluated : fission chamber (FC)... more In-Port detectors: Two types of candidate neutron detectors were evaluated : fission chamber (FC) with 238 U as fissile material and diamond detector.
ITER is an experimental nuclear reactor, aiming to demonstrate the feasibility of nuclear fusion ... more ITER is an experimental nuclear reactor, aiming to demonstrate the feasibility of nuclear fusion realization in order to use it as a new source of energy. ITER is a plasma device (tokamak type) which will be equipped with a set of plasma diagnostic tools to satisfy three key requirements: machine protection, plasma control and physics studies by measuring about 100 different parameters. ITER diagnostic equipment is integrated in several ports at upper, equatorial and divertor levels as well internally in many vacuum vessel locations. The Diagnostic Systems will be procured from ITER Members (Japan,
ABSTRACT –The radionuclide 55Fe (t1/2 5 2.73 years) is one of the radionuclides produced in large... more ABSTRACT –The radionuclide 55Fe (t1/2 5 2.73 years) is one of the radionuclides produced in large quantities inside a fusion reactor. The excitation function of the (n,p) reaction from threshold to 20 MeV and proton emission spectra from the 55Fe target at 14-MeV neutron energy are calculated using optimized input parameters in the nuclear reaction modular codes EMPIRE-3.1 and TALYS-1.4. The codes account for the major nuclear reaction mechanisms, including direct, preequilibrium, and compound nucleus contributions. The present results of 55Fe(n,p)55Mn are compared with the existing evaluated nuclear data libraries ROSFOND-2010, JEFF-3.1, and EAF-2010 along with systematics around 14-MeV neutron energy. The prediction accuracy of the present calculation is considered to satisfy the requirementfor fusion reactor applications. The theoretical nuclear model calculations with a reliable parameter set up to 20 MeV are recommended to estimate the cross section of radionuclides or unstable targets in the mass region A * 50 to 60. The present work is an important step to study the cross section of the 55Fe(n,p)55Mn reaction by a surrogate method.
Fusion power output of ITER is measured by a group of neutron flux monitors combined with a neutr... more Fusion power output of ITER is measured by a group of neutron flux monitors combined with a neutron activation system and neutron profile monitors. These systems should be absolutely calibrated by use of DD/DT generators moving inside the ITER vacuum vessel (in-situ calibration). Each neutron monitor has a limited measurement range of emission rate, but the ranges are connected by cross-calibration using the ITER plasma with at least one decade overlapping. The over all dynamic range covered by the group of neutron flux monitors is 10 14 n/sec to 10 21 n/sec. Effects of vertical/radial movement of plasma on the measurement accuracy were reviewed. It was found that cross-calibration using specially planned jog shots, and a vertical neutron camera is important to minimize the inaccuracy caused by the plasma movement.
Flux measurement of an accelerator based D-T neutron generator was achieved by the activation tec... more Flux measurement of an accelerator based D-T neutron generator was achieved by the activation technique. The neutron generator can produce maximum neutron yield of 1.9x 10 10 n1sec at the Tritium-target For the measurement of 14 MeV neutron Dux, 63Cu(n, 2n) 62 Cu and 27AI(n, p)27Mg reactions are most suitable because of their higher threshold energies 11.03 MeV and 3.25 MeV respectively. Measurement ofy-ray activities from 62CU and 27Mg is used to measure 14 MeV neutron Dux. NaI(TI) scintillation and High Purity Germanium (HPGe) detectors were used for the y-radiation measurement from 62CU and 27Mg respectively. In this paper the 14 MeV neutron Dux measurement by 63CU and 27AI activation is discussed. The method could also serve as a diagnostics tool for measurement of high-energy neutron Dux.
Neutron field parameter measurements on the JET tokamak by means of super-heated fluid detectors ... more Neutron field parameter measurements on the JET tokamak by means of super-heated fluid detectors Rev. Sci. Instrum. 83, 10E124 (2012) HELIOS: A helium line-ratio spectral-monitoring diagnostic used to generate high resolution profiles near the ion cyclotron resonant heating antenna on TEXTOR Rev. Sci. Instrum. 83, 10D722 δf Monte Carlo calculation of neoclassical transport in perturbed tokamaks Phys. Plasmas 19, 082503 Active spectroscopic measurements of the bulk deuterium properties in the DIII-D tokamak (invited) Rev. Sci. Instrum. 83, 10D529 A novel local equilibrium model for shaped tokamak plasmas Phys. Plasmas 19, 072520 Additional information on Rev. Sci. Instrum.
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Papers by Shrichand Jakhar