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High-Z impurities released from plasma-material interactions have been shown to limit the performance of fusion plasmas, and understanding these impurity transport mechanisms throughout the...

The next generation nuclear facilities like Gen-IV fission reactors and fusion plasma will have a huge amount of activated waste production and resulting harmful consequences in terms of radioactive responses such as activity, decay heat, and dose. It is imperative to understand and quantify the impact of individual parent elements or isotopes in the material on major radiological responses. Such quantification serves as an impact indicator. This paper attempts to develop a method to aid this quantification that would eventually offer a complete material activation analysis. Here, we begin by presenting the mathematical formulation to account for the contribution of the parent constituents of any irradiated material toward the radiological responses directly, defined as the contributing factor (CF). The method is easily adaptable to other activation solvers and provides the user with CFs of parents that highlight the individual importance of the constituents. These factors can be used to determine...

ITER will use a Pellet Injection System (PIS) for supplying deuterium-tritium (D-T) fuel to the fusion plasma and a Shattered Pellet Injection (SPI) system for rapidly injecting impurities (argon or neon mixed with deuterium) as solidified pellets into the plasma for the purpose of mitigating the harmful effects of plasma disruptions as part of a Disruption Mitigation System (DMS). Both systems are being designed to handle significant amounts of tritium in the process streams and are exposed to similar environmental conditions during operation, including exposure to gamma and neutron radiation and significant magnetic fields. Multiple barriers to prevent the potential release of the tritium inventory into the environment are included in the designs. The unique environmental conditions present some challenges and are currently being addressed during the design phase.

Thomson scattering (TS) is one of the most reliable diagnostics to measure the electron temperature and electron density radial profiles in fusion plasmas. In GAMMA 10, a yttrium-aluminum-garnet (Y...

Due to the variety of different kinds of plasmas and the multitude of effects, occurrences and possible applications, plasma physics is a broad field of research with numerous text books and monogr...

Validation of physics models using the newly uncovered physics with a 2-D electron cyclotron emission imaging (ECEi) system for magnetic fusion plasmas has either enhanced the confidence or substantially improved the modeling capability. The discarded “full reconnection model” in sawtooth instability is vindicated and established that symmetry and magnetic shear of the 1/1 kink mode are critical parameters in sawtooth instability. For the 2/1 instability, it is demonstrated that the 2-D data can determine critical physics parameters with a high confidence and the measured anisotropic distribution of the turbulence and its flow in presence of the 2/1 island is validated by the modelled potential and gyro-kinetic calculation. The validation process of the measured reversed-shear Alfvéneigenmode (RSAE) structures has improved deficiencies of prior models. The 2-D images of internal structure of the ELMs and turbulence induced by the resonant magnetic perturbation (RMP) have provided an opportunity to establish firm physics basis of the ELM instability and role of RMPs. The importance of symmetry in determining the reconnection time scale and role of magnetic shear of the 1/1 kink mode in sawtooth instability may be relevant to the underlying physics of the violent kink instability of the filament ropes in a solar flare.

Magnetic fusion energy (MFE) research requires ultrahigh-vacuum (UHV) conditions, primarily to reduce plasma contamination by impurities. For radiofrequency (RF)-heated plasmas, a great benefit may accrue from a non-conducting vacuum vessel, allowing external RF antennas which avoids the complications and cost of internal antennas and high-voltage high-current feedthroughs. In this paper we describe these and other criteria, e.g., safety, availability, design flexibility, structural integrity, access, outgassing, transparency, and fabrication techniques that led to the selection and use of 25.4-cm OD, 1.6-cm wall polycarbonate pipe as the main vacuum vessel for an MFE research device whose plasmas are expected to reach keV energies for durations exceeding 0.1 s

Development of a new linear device for confinement of fusion plasmas is under way in the Budker Institute of Nuclear Physics, Novosibirsk. The new device combines features of existing GOL-3 and GDT...

A high-enthalpy plasma facility with 0.4 MW power level has been constructed at Chonbuk National University in Korea. A segmented arc plasma torch was adopted as a plasma source for this facility. ...

To achieve real-time control of fusion plasmas, the flux distribution and derived quantities have to be calculated within the time of the machine control cycle, which in the case of the ASDEX-Upgra...

The buildup of the energetic particle population in fusion plasmas is typically slow compared to the growth times of energetic-particle driven instabilities. This feature draws special attention to...

Interaction between shear flows and plasma instabilities in axially symmetric mirrors can lead to improved confinement, observed both in experiments on the gas dynamic trap and in simulations. Shear flows, driven via biased end plates and limiters, in combination with finite-larmor-radius effects are shown to be efficient in confining high-beta plasmas even with a magnetic hill on axis. Interpretation of observed effects such as vortex confinement, i.e., confinement of the plasma core in the dead-flow zone of the driven vortex, is shown to agree well with simulations. Theoretical scaling laws predict such a confinement scheme to be useful even in fusion plasmas.

The magnetohydrodynamic model for fusion plasma dynamics governs the large-scale equilibrium properties, and sets the most stringent constraints on the parameter space accessible without violent di...

The control of wall loads in fusion devices, in particular with respect to the life time limitations of wall components due to material erosion and migration, will be decisive for the realisation o...

For future burning plasma experiments, all diagnostics must be re-evaluated in terms of their measurement capabilities and robustness in the harsh, high-temperature environment. This is certainly true for interferometry measurements where conventional approaches may not be ideal and interpretation may require modification due to high plasma temperatures. Optimizing these systems to provide maximum information is crucial to understanding burning plasma dynamics. This paper explores a variety of phase measurement techniques for the main body and divertor regions that can be utilized on fusion plasma experiments like ITER and beyond.

A study of fluctuation is one of main issues in fusion plasma researches. In the tandem mirror GAMMA10, a potential fluctuation changes during the formation of confinement potential with the application of electron cyclotron heating (ECH). Potential fluctuation induces radial particle transports. We have studied the radial profiles of the potential fluctuation during the application of ECH. The potential in the central cell of GAMMA10 is measured by a gold neutral beam probe (GNBP) system. GNBP is a useful tool for the study of radial potential and its fluctuation directly in the fusion plasmas. It was confirmed that the stronger radial potential was formed during the application of plug ECH than that without plug-ECH.

The effect of the plasma flow on stability and transport has attracted much interest on fusion plasma research. In the GAMMA 10 tandem mirror, plasmas are mainly produced and heated with Ion Cyclotron Range of Frequency (ICRF) waves. High temperature plasmas are confined in the central cell. Two Mach probes, which have four tips facing direction of every 90 degrees, are installed on east and west sides of the central cell. It is found that the plasma flows from west to east directions with the pitch angle of around 60 degrees. The averaged Mach number of near 0.3 is detected on both sides of the central cell. The driven mechanism of the plasma flow is now under investigation.

Principal techniques and trends in the validation and analysis of data in magnetic fusion research are described and examples of applications are given. Well-established methods to obtain key physical quantities are outlined, as well as newer techniques employing integrated analysis of multiple diagnostics to improve quality and extract additional information from the data. Plasma control, confinement scaling, and transport studies, including model validation and development, are presented as important examples of applications of validated data. Finally, aspects essential to successful operation of future devices, which bring challenges due to a harsher environment for diagnostics, increased real-time requirements, and a geographically more distributed user community, are highlighted.

Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically confined fusion plasmas, both in determining the effects of impurities on ...

An overview of erosion and deposition processes in fusion machines is presented. The underlying physical and chemical mechanisms are explained. The impact of erosion and deposition on wall lifetime...

Quantitative predictions of propagation, emission, and absorption of electron cyclotron (EC) waves rely on a solid theoretical background and are routinely employed in the analysis and preparation ...

Recent progress on the worldwide development of gyrotrons for fusion application is presented. After breakthroughs of gyrotron technologies in the 1990s, significant progress has been made in the 2000s, in particular, on a long-pulse gyrotron for a wide range of frequencies from 84 to 170 GHz. And, activities for advanced gyrotrons, for example, a high-power gyrotron using a coaxial resonator, a multifrequency gyrotron, etc., have proceeded. With this progress have come improvements of gyrotron components such as a high-efficiency mode converter, a wide-band window, etc. The gyrotrons have been applied to major fusion devices for heating and magnetohydrodynamics controls. At present, the development of a 1-MW-class continuous-wave gyrotron is in the scope, which is applicable for the self-ignition experiment of fusion plasma and its confinement at the International Thermonuclear Experimental Reactor (ITER).

The statistical description of a hot, magnetized, and classical plasma is reviewed. The latter represents the appropriate model for a fusion plasma in magnetic confinement. Approaches for (reduced)...

In the core of a burning fusion plasma, the contamination by impurities has to be kept below a critical level. Understanding and control of impurity transport and accumulation are thus an essential...

Diagnostic development is an important and vital part of the fusion program. There is close coupling between the physics needs for measurements and the diagnostic development that receives funding. This paper gives brief technical descriptions of ongoing developments in a few areas currently receiving attention. These areas include T{sub e} diagnostics, j(R) diagnostics applicable to new regimes, and diagnostics to probe edge and core turbulence. The underlying physics motivation and enabling technologies involved in these developments are also mentioned. A brief status of diagnostic work in support of a burning plasma experiment (BPX) is also described, since this effort may become more significant worldwide. Several diagnostic R and D topics, identified as crucial for a BPX, are discussed.

Significant advances in microwave and millimeter wave technology have enabled the development of a new generation of imaging diagnostics as a visualization tool in this frequency region. Millimeter...

Fusion plasma performance and confinement studies on JT-60 and JT-60U are reviewed. With the main aim of providing a physics basis for ITER and the steady-state tokamak reactors, JT-60/JT-60U has b...

A GAMMACELL system has been designed for measurement of high-energy gamma rays generated in fusion plasma nuclear reactions. A compact gamma-ray spectrometry system providing high efficiency, low background count-rate, low neutron sensitivity, and high radiation resistance was the object of the present work. The paper describes design of the system and results of in-beam test experiments.

Liquids may be used between the magnetic confined fusion plasma and the first wall of the plasma chamber to reduce the material damage through displacements per atom (dpa) and helium gas production. This could extend the lifetime of the first wall in a magnetic fusion energy (MFE) reactor to a plant lifetime of similar to 30 yr.

Research in plasma physics and in controlled thermonuclear fusion (CTF) is an interdisciplinary field that involves the understanding and the solution of a new type of physical problem. Efforts to find scientific proof of the feasibility of CTF in the laboratory have led to the development of innovative ideas about the behavior of collective nonequilibrium systems that are of relevance in other areas of physics. 17 refs., 1 tab.

A novel diagnostic f or ion temperature and density is discussed. The diagnostic, based on the detection of the 24-MeV gamma photon from the D(d,γ)4He fusion reaction, appears feasible in reactor-o...

A Monte Carlo program for simulating plasma ions incident on a surface with a floating potential is presented. This program is used for calculating sputtering, backscattering, and implantation valu...

The primary objectives of control are somewhat different from those of much of fusion plasma physics. Magnetic fusion physics has historically focused on understanding the physics of plasmas in magnetic confinement devices, whereas fusion plasma control seeks to capitalize on the understanding already gained to cause the system (fusion device plus plasma) to behave in certain desirable ways. For example, early uses of plasma control in fusion devices had simple goals such as extending the survival of discharges by minimizing plasma-wall interaction or by regulating density. Present applications are primarily aimed at achieving conditions with better potential fusion performance or conditions under which fusion plasmas can be more easily studied. The demanding performance requirements and significant constraints expected on control of future fusion reactors suggest that plasma control is a critical enabling technology for progress toward commercial fusion power. A greater understanding of control t...

Many authors have investigated stability characteristics and performance of various burn control schemes. The work presented here represents the first application of optimal control theory to the problem of fusion plasma thermal stabilization. The objectives of this initial investigation were to develop analysis methods, demonstrate tractability, and present some preliminary results of optimal control theory in burn control research.

Teaching in fusion at the University of Illinois is an integrated part of the nuclear engineering curriculum. Through the use of two key courses, ''Introduction to Fusion'' and ''Fusion Systems,'' basic preparation for those wishing to specialize in fusion is provided. These courses are primarily directed to plasma aspects of fusion, but materials and other engineering aspects have been integrated into the curriculum through a broadened coverage in such existing courses as nuclear materials, shielding, and reactor physics. Research is primarily focused at the PhD level, although some MS studies are in progress. While current theses involve a wide variety of topics, one major area being pursued is the study of advanced fuel (non-deuterium-tritium) reactors based on two-component fusion and other concepts. This effort consists of a series of loosely knit subtasks related to such problems as cyclotron emission and direct energy conversion. Also, various research involving charge-exchange losses during neutral-beam injection, vacuum-wall sputtering, and related topics has developed as a direct outgrowth of the PROMETHEUS project, which involved the conceptual design of a power-consuming mirror-type reactor for materials and engineering tests. (auth)

Experimental work on the dense-plasma focus device Julich I is presented. The main objective of this program was the development of a neutron source for controlled thermonuclear reactor application...

A computer code has been developed that solves the transport equation for cyclotron radiation in an arbitrary axisymmetric system. The physics underlying the transport is discussed and the method o...

Studies of atomic structure are being extended into highly ionised regimes in which relativistic and quantum electrodynamic interactions and effects due to the finite size of the nucleus may dominate the dynamical structure of the ions. These highly ionised atoms have important applications in astrophysics, fusion plasma and X-ray laser technology, and provide new tests of computational atomic theory.

A method to determine the contributions to plasma contamination and to surface erosion arising from synergistic effects under multiple-component irradiation is discussed. Some examples of situations that are likely to give rise to synergistic phenomena are given. (MOW)

The need of the fusion energy program for high power mm-wave sources for use in plasma heating experiments has resulted in the rapid development of gyrotron oscillators.

Alpha particles will interact with the ablation cloud surrounding an injected pellet via charge-exchange (CX) and nuclear reactions. The use of these interactions to diagnose fast confined alphas in a fusion plasma is discussed. Measurement of helium neutrals from multiple CX interactions should allow determination of the incident alpha-energy distribution.