Impact of minority concentration on fundamental (H)D ICRF heating performance in JET-ILW

ITER will start its operation with non-activated hydrogen and helium plasmas at a reduced magnetic field of B-0 = 2.65 T. In hydrogen plasmas, the two ion cyclotron resonance frequency (ICRF) heating schemes available for central plasma heating (fundamental H majority and 2nd harmonic He-3 minority ICRF heating) are likely to suffer from relatively low RF wave absorption, as suggested by numerical modelling and confirmed by previous JET experiments conducted in conditions similar to those expected in ITER's initial phase. With He-4 plasmas, the commonly adopted fundamental H minority heating scheme will be used and its performance is expected to be much better. However, one important question that remains to be answered is whether increased levels of hydrogen (due to e. g. H pellet injection) jeopardize the high performance usually observed with this heating scheme, in particular in a full-metal environment. Recent JET experiments performed with the ITER-likewall shed some light onto this question and the main results concerning ICRF heating performance in L-mode discharges are summarized here

Mapping decision-making and opportunities for improving energy efficiency across the mid-tier HVAC maintenance lifecycle

This report looks at the HVAC maintenance lifecycle to outline the decision-making processes that characterise the procurement of HVAC management and maintenance services in mid-tier commercial buildings. It maps a range of policy options against key issues identified across the HVAC maintenance lifecycle

Understanding the barriers to skills development for energy efficiency in commercial building HVAC

Decarbonising Australia’s building stock is critical to meeting commitments to global climate agreements and creating more liveable built environments. This report addresses the potential for capacity-building for energy efficiency in the workforce responsible for managing and maintaining commercial buildings

Identifying common issues in mid-tier HVAC maintenance: Commercial Offices, Aged Care, Hotels and Shopping Centre

This report outlines to what extent the issues identified in the Better Ways to Work Report extend to sectors beyond mid-tier commercial office buildings. This report considers common issues across commercial office buildings, aged care, hotels and shopping centres

Fundamental cyclotron 3He minority ICRF heating experiments in H plasmas in JET in presence of the ILW

Efficient plasma heating schemes are a prerequisite for reaching fusion relevant temperatures in fusion machines. On the road to reaching ignition, non-activated scenarios - such as (3He

Asymmetric emission of high energy electrons in the two-dimensional hydrodynamic expansion of large xenon clusters irradiated by intense laser fields

Energy spectra and angular distributions have been measured of electrons that are emitted upon disassembly of $Xe_{150000}$ following irradiation by intense (10$^{15}-10^{16}$ W cm$^{-2}$) laser pulses whose durations are varied over the 100-2200 fs range. The cluster explosion dynamics occur in the hydrodynamic regime. Electron emission is found to be unexpectedly asymmetric and exhibits a resonance when the laser pulse duration is $\sim$1 ps. These results are rationalized by extending the hydrodynamic model to also take into account the force that the light field exerts on the polarization charge that is induced on surface of the cluster. We show that the magnitude of this electrostrictive force is comparable to those of Coulombic and the hydrodynamic forces, and it exhibits resonance behavior. Contrary to earlier understanding, we find that low-energy electrons are connected to the resonance in energy absorption by the cluster. The high-energy electrons seem to be produced by a mechanism that is not so strongly influenced by the resonance.Comment: 1 Revtex file, 8 figs. in eps forma

N=2 ICRH of H majority plasmas in JET-ILW

Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = w(ci)) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w =2w(ci)) typically requires pre-heating of the plasma ions to become efficient. Recently, w =2wci ICRF heating was tested in JET-ILW hydrogen plasmas in the absence of neutral beam injection (L-mode). Despite the lack of pre-heating, up to 6MW of ICRF power were coupled to the plasma leading to a transition to H-mode for P-ICRH>5MW in most discharges. Heating efficiencies between 0.65-0.85 were achieved as a combination of the low magnetic field adopted (enhanced finite Larmor radius effects) and the deliberate slow rise of the ICRF power, allowing time for a fast ion population to gradually build-up leading to a systematic increase of the wave absorptivity. Although fast ion tails are a common feature of harmonic ICRF heating, the N=2 majority heating features moderate tail energies (<500keV) except at very low plasma densities (n(e0)<3x10(19)/m(3)), where fast H tails in the MeV range developed and fast ion losses became significant, leading to enhanced plasma wall interaction. The main results of these experiments will be reported