An experiment has been performed at the Joint European Torus (JET) which has demonstratedclear self-heating of a deuterium-tritium plasma by alpha particles produced in fusion reactions. Since the alpha power was approximately 10% of the total power absorbed by the plasma, the heating was distinguished from other changes, due to isotopic effects, by scanning the plasma and neutral beam mixtures together from pure D to nearly pure T in a hot ion H-mode with 10.5MW neutral beam power. At an optimum mixture of 60±20% T, the fusion gain (=P fusion / P absorbed ) was 0.65 and the alpha heating showed clearly as a maximum in electron temperature.

High power combined NB+ICRF (H)D heating experiments have been carried out in the JET MKIIa divertor configuration, both in deuterium (DD) and in deuterium-tritium (DT) plasmas. Results from a wide range of RF injected power, up to 9.5 MW, NB power up to 22 MW, plasma currents, up to 4.2 MA, and toroidal field values, up to 3.6 T, show a clear improvement in electron temperature, DD reactivity and stored energy with respect to NB only discharges. High energy Neutral Particle Analyser (NPA) data show that acceleration of the NB injected Deuterons takes place at the second harmonic deuterium resonance. This is confirmed by numerical simulations with the PION code. Experiments have also been carried out in the (He 3 )D heating scenario. ICRF heating has been an essential ingredient in the DT experiments in the ELM-free Hot-Ion regime, contributing to the achievement of a record fusion power of 16.1 MW and a record stored energy of 17 MJ.

Seismic and electromagnetic properties are generally anisotropic, depending on the microscale rock fabric and the macroscale stress field. We have assessed the stress-dependent anisotropy of poorly consolidated (porosity of approximately 0.35) sandstones (broadly representative of shallow reservoirs) experimentally, combining ultrasonic (0.6 MHz P-wave velocity, VP, and attenuation 1/QP) and electrical resistivity measurements. We used three cores from an outcrop sandstone sample extracted at 0°, 45°, and 90° angles with respect to the visible geologic bedding plane and subjected them to unloading/loading cycles with variations of the confining (20–35 MPa) and pore (2–17 MPa) pressures. Our results indicate that stress field orientation, loading history, rock fabric, and the measurement scale, all affect the elastic and electrical anisotropies. Strong linear correlations (R2 > 0.9) between VP, 1/QP, and resistivity in the three considered directions suggest that the stress orientation similarly affects the elastic and electrical properties of poorly consolidated, high-porosity (shallow) sandstone reservoirs. However, resistivity is more sensitive to pore pressure changes (effective stress coefficients n > 1), whereas P-wave properties provide simultaneous information about the confining (from VP, with n slightly less than 1) and pore pressure (from 1/QP, with n slightly greater than 1) variations. We found n is also anisotropic for the three measured properties because a more intense and rapid grain rearrangement occurs when the stress field changes result from oblique stress orientations with respect to rock layering. Altogether, our results highlighted the potential of joint elastic-electrical stress-dependent anisotropy assessments to enhance the geomechanical interpretation of reservoirs during production or injection activities.

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