Abstract-Since 1993, when the European Space Agency (ESA) proposed the use of GNSS reflected signals for sea mesoscale altimetry, a wide range of applications have appeared. This work focuses on the retrieval of Significant Wave Height (SWH) and the Mean Sea Surface Level (MSSL) from a ground-based experiment using the Interference Pattern Technique (IPT). Two different observables on the IPT are analyzed: the oscillation frequency, and the angle where coherency is lost. The point where coherency in the reflection process is lost can be related to the Rayleigh criterion for smooth surfaces and helps to determine the SWH. Spectral analysis on the interference pattern helps to determine the MSSL. A three-month field campaign was performed on the "Pont del Petroli" pier, Badalona, Spain, to see how the reflected GNSS signals were affected by coastal sea state, and check previous assumptions. Results from this field experiment are shown confirming that the SWH can be retrieved with an accuracy of 6 cm and the MSSL with 4 cm. Estimations of both parameters are obtained every 30 minutes approximately.

This paper presents the latest results on confinement studies in the TJ-II stellarator. The inherently strong plasma–wall interaction of TJ-II has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z, Li was chosen because there exists a reactor-oriented interest in this element, thus giving special relevance to the investigation of its properties. The Li-coating has led to important changes in plasma performance. Particularly, the effective density limit in NBI plasmas has been extended reaching central values of 8 × 1019 m−3 and T e ≈ 250–300 eV, with peaked density, rather flat T e profiles and higher ion temperatures. Due to the achieved density control, a second type of transition has been added to the low density ones previously observed in ECRH plasmas: higher density transitions characterized by the fall in Hα emission, the onset of steep density gradient and the reduction in the turbulence; which are characteristics of transition to the H mode. Confinement studies in ECH plasmas indicate that lowest order magnetic resonances, even in a low shear environment, locally reduce the effective electron heat diffusivities, while Alfven eigenmodes destabilized in NBI plasmas can influence fast ion confinement.

Reflectometry using Global Navigation Satellite System's signals (GNSS-R) of opportunity was originally conceived in the early 1990 s for mesoscale altimetry, and since then, many studies have shown its applicability to other remote sensing applications such as sea state determination, soil moisture, vegetation, snow monitoring, etc. In December 2012, the Phase A studies of ESA's PAssive Reflectometry and Interferometry System In-orbit Demonstration (PARIS IoD) mission concluded. In conventional GNSS-R (cGNSS-R), the satellite navigation signals scattered over the Earth's surface are cross-correlated with a locally generated replica of the transmitted ones shifted in frequency ( ), and in delay ( τ). However, in PARIS, a different technique called interferometric GNSS-R (iGNSS-R) is used, which allows the use of the whole signal's bandwidth, and improve the altimetry precision, despite the large bandwidth signals' codes being not publically available. This is achieved by using the direct signal collected by a directive antenna, instead of the locally generated replica. This study presents a methodology to optimize the configuration of a generic iGNSS-R altimeter, and evaluate its performance. The methodology presented is then particularized to a PARIS IoD-like case.

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