A particle-in-cell calculation code was made to simulate the operation of an inertial electrostatic confinement (IEC) fusion device. The computation includes the effects of ionization by electron impact. Several techniques to save computational time are introduced in this program code. One of them is time-dependent fine space meshes used in the regions where the particles concentrate. Several superparticles that have similar radial position as well as similar energy are merged, while one superparticle is divided into several particles with a somewhat different velocity when the total number of superparticles decreases. The methods enable more precise determination of the characteristics of an IEC device in a shorter time than by previous methods.

“Double-well” potential structure (virtual cathode formation) is studied in a spherical inertial electrostatic confinement (SIEC) device using non-linear Poisson's equation. Particle densities are derived from a kinetic equation equivalent to Vlasov's equation. Velocities of collision-free electrons and ions at the edge of the configuration will be almost aligned towards the center, however, they have small divergences. Analyses show appearance of a virtual cathode potential well relevant to bum fusion fuels near the center of SIEC.

Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion.Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m2 and reached a maximum surface temperature of 593 °C for uniform power loading of 3 kW absorbed on a 2-cm2 area. An impressive 10 kW of power was absorbed on an area of 24 cm2.Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum resistance temperature devices (RTDs) for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels.The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m2 using 50 °C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented.

As part of the Electron Cyclotron Heating (ECH) Facility upgrade at DIII–D an 8.4 MW Modulator/Regulator Power System was designed and constructed using acquired hardware from the Mirror Fusion Test Facility (MFTF) at Lawrence Livermore National Laboratory (LLNL) program as a foundation.1 Design changes in the feedback control of the modulator/regulator (M/R) was motivated by the need for improved output voltage regulation and improved capability to modulate the output voltage consistent with reference command signals containing modulation patterns (typically square wave). The regulation characteristics of the old ECH M/R power system had previously constrained gyrotron operation due to marginal voltage control loop stability and slow response to voltage step changes. The technical approach was to develop models of the circuit functions of the M/R controller from the circuit diagrams, and then examine the control characteristics using circuit analysis software. MATLAB® Simulink® and Intusoft IsSPICE4® (SPICE) codes were used to examine the control issues. These analysis software tools were used to simulate the controller functions and yielded identical results. The SPICE circuit model was selected as a baseline for future maintenance by the engineering staff. The analysis of the controller model blocks provided the needed information to modify the controller circuits. Changes made to the controller included addition of a voltage feedback loop around the grid driver amplifier for the power tetrode control grid in the M/R, and changes to the feedback loop compensation of the main error amplifier. The implemented revised controller performance matches the model performance predictions remarkably well. This paper describes the circuit models, implementation of the revisions to the controller, and recent operational results.

(2001). 14th Topical Meeting on the Technology of Fusion Energy. Fusion Technology: Vol. 39, Proceedings of the Fourteenth Tropical Meeting on The Technology of Fusion Energy. October 15-19, 2000. Park City, Utah, pp. xvi-xvi.

The optimized design of one-side-heated plasma-facing components (PFC) is dependent on knowing the local distribution of inside wall heat flux in the flow channels. The local inside wall heat flux can be obtained from selectively chosen local PFC wall temperatures close to the inside boundary of the flow channel. To this end, three-dimensional thermal measurements for a one-side-heated monoblock were made and show: (1) the three-dimensional variation of the wall temperature close to both the heated and fluid-solid surface boundaries, (2) the resultant effects of local subcooled flow boiling on the 3-D wall temperature/outside heat flux relationship – one of which is the 3-D wall temperature profile is almost unchanged in the vicinity for incident heat flux levels between the onset to fully developed boiling and CHF, and (3) the occurrence of local CHF and local post-CHF. The monoblock has a 180.0 mm heated length, has a 10.0 mm inside diameter, and has a circular-like cross-section with a 30.0 mm nominal outside diameter.

In some experiments, intense electron fluxes were made to encounter high proton concentrations to achieve p + e fusions. Anomalies were observed: The electron energies were often below the threshold energy, and the cross-section results were unexpectedly high. A twofold mechanism consisting of hydrogen squeezed atom formation and of virtual neutron absorption is suggested to justify the observed anomalous nuclear events. The hypothesis is extended to the d + e reaction.

A preliminary study on the direct-contact condensation in the ITER pressure suppression tank during the ICE event was performed experimentally and analytically. The water-vapor two phase flow behavior in the depressurized water tank was investigated by the flow visualization experiment and it was found that the present numerical approach is very effective to predict the condensation effect in the ITER suppression tank during the ICE event.

ARIES-AT is a 1000 MWe conceptual fusion power plant design with a very low projected cost of electricity. The design contains many innovative features to improve both the physics and engineering performance of the system. From the safety and environmental perspective, there is greater depth to the overall analysis than in past ARIES studies. For ARIES-AT, the overall spectrum of off-normal events to be examined has been broadened. They include conventional loss of coolant and loss of flow events, an ex-vessel loss of coolant, and in-vessel off-normal events that mobilize in-vessel inventories (e.g. tritium and tokamak dust) and bypass primary confinement such as a Loss of Vacuum and an in-vessel loss of coolant with bypass. This broader examination of accidents improves the robustness of the design from the safety perspective and gives additional confidence that the facility can meet the no-evacuation requirement. We also provide a systematic assessment of the design to address key safety functions such as confinement, decay heat removal, and chemical energy control. In the area of waste management, waste is classified by both the volume of the component and its hazard. In comparison to previous ARIES designs, the overall waste volume is less because of the compact design.