High-performance and long-pulse operation is a crucial goal of current magnetic fusion research. Here, we demonstrate a high-connement plasma regime known as an H-mode with a record pulse length of ...over 30 s in the Experimental Advanced Superconducting Tokamak sustained by lower hybrid wave current drive (LHCD) with advanced lithium wall conditioning. We nd that LHCD provides a exible boundary control for a ubiquitous edge instability in H-mode plasmas known as an edge-localized mode, which leads to a marked reduction in the heat load on the vessel wall compared with standard edge-localized modes. LHCD also induces edge plasma ergodization that broadens the heat deposition footprint. The heat transport caused by this ergodization can be actively controlled by regulating the edge plasma conditions. This potentially offers a new means for heat-ux control, which is a key issue for next-step fusion development. PUBLICATION ABSTRACT
This article aims to provide deep insight into the physics of substrates for RF applications under large-amplitude signal excitations. The impact of physical parameters on substrate-induced harmonic ...distortion is modeled and well understood, from a theoretical and quantitative standpoint. This article formulates the interplay between applied voltage signal (dc or RF), interface fixed charge, and trapped charge in a charge-balance analysis for high-resistivity and trap-rich (TR) substrates. A TCAD approach gives strong insight into the impact of such semiconductor material and interface properties on the RF substrate's effective resistivity and linearity. First, a static analysis reveals how TR interface passivation overcomes the parasitic surface conduction effect using the concept of deep Fermi-level pinning. Next, substrates are analyzed in response to dynamic excitation signals. Using step functions to pulse an MOS structure from strong negative to strong positive applied charge sheds light on carrier dynamics. The characteristic time constants associated with variations in trap occupancy and in free carrier densities are discussed. Finally, sinusoidal large-amplitude signals are considered to analyze harmonic distortion from several types of substrates at various RF frequencies.
This article presents the accurate modeling results of the nonlinear behavior of a wide range of silicon-based substrates at RF. The TCAD-based model includes carrier inertia effects and captures the ...transient nonequilibrium phenomena in the semiconductor substrate regions in response to a large-amplitude RF signal. The model is applied to coplanar waveguide (CPW) lines measured on 19 different silicon-based samples that have key differences in their material and interface parameters, such as different values for nominal doping, interface oxide charge, the presence or not of a trap-rich passivation layer, and characteristic dimensions. Furthermore, the CPW line's distortion levels are measured from 25 °C up to 175 °C and at five fundamental frequencies under large-signal excitation from 50 MHz to 5.4 GHz. An excellent model to experiment correlation is achieved under all of these conditions, and the impact of the material and excitation parameters are discussed with strong physical insight provided by the simulation tool.
A novel method for increasing the effective resistivity in low-doped silicon substrates is presented. By creating a chain series of p-n depletion junctions beneath the insulator, the parasitic ...surface conduction channel is interrupted, significantly lowering substrate losses and reducing harmonic distortion in the simulated and measured CPW lines achieving performance close to the widely used trap-rich silicon substrate at RF frequencies.
This paper proposes an original approach to separately characterize self-heating and substrate effects in Fully-Depleted Silicon-on-Insulator (FD-SOI) devices. As both dynamic self-heating and drain ...to source coupling through the back-gate and substrate of an FD-SOI MOSFET induce a frequency transition in the Y-parameters in a common frequency range, it is crucial to properly separate them for further modeling. The proposed novel method is based on the extraction of the back-gate and substrate networks from the S-parameters measured at the zero-temperature coefficient bias. It enables the accurate and unambiguous extraction of thermal impedance for different biases, thus providing the extraction of the device thermal resistance and capacitance for different power levels from S-parameters measurements.
An experimental database of the power spreading into the target private flux region (S-factor) from ASDEX Upgrade and JET outer target data has been gathered and analysed. The power spreading, ...combined with the Scrape-Off Layer heat flux decay length λq, determines the power exhaust channel width at the divertor target. In terms of main plasma parameters, we find that the poloidal magnetic field plays a major role S∼Bpol-1 in both L-mode and H-mode plasmas, similarly to λq. Combining JET and AUG data in H-mode with open divertor we obtain a strong and beneficial major radius dependency and no plasma density influence is found. For closed AUG divII configurations in L-mode, however, larger upstream ne clearly broadens S. Interestingly, the scaling of S with divertor parameters, reveals that only target Te is needed to account for its variation. SOLPS simulations with fixed perpendicular transport reproduce most of the observed phenomenology, suggesting that the observed larger S in closed versus open divertor configuration is simply due to different target Te generated by larger parallel gradients.
This paper focuses on the comparison of various advanced substrates such as trap-rich (TR), porous silicon (PSi), gold-doped (Au-Si) and smart-implants PN-junction (DP) in terms of RF performances. ...Both small- and large-signal measurements were performed, including the study of the influence of temperature and DC bias voltage. The purpose of this paper is to provide an overview, and a more in-depth analysis of DP substrate, of the characteristics of these multiple substrates to facilitate design choices for RF-IC applications.
A solid-phase methodology to synthesize oligopeptides, specifically incorporating serine residues linked to ADP-ribose (ADPr), is presented. Through the synthesis of both α- and β-anomers of the ...phosphoribosylated Fmoc-Ser building block and their usage in our modified solid-phase peptide synthesis protocol, both α- and β-ADPr peptides from a naturally Ser-ADPr containing H2B sequence were obtained. With these, and by digestion studies using the human glycohydrolase, ARH3 (hARH3), compelling evidence is obtained that the α-Ser-ADPr linkage comprises the naturally occurring configuration.
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