Using foraminifera in STEMSEAS Site 1 to understand the recent paleoceanographic and paleoclimatic history of Tanner Basin, California Borderland

In May of 2016, the STEMSEAS Educational Transit cruise OC1605-tranA collected the STEMSEAS Site 1 core from the Tanner Basin in the California Borderland. This research serves as the first formal survey of the foraminifera preserved within that core. The purpose of this research is to use foraminifera preserved within that core to understand the recent depositional and paleoenvironmental conditions at Site 1, and to place that information into a regional paleoceanographic and paleoclimatic context. In pursuing this purpose, this research aims to answer three questions: 1) Can biostratigraphic markers in the foraminiferal assemblages in STEMSEAS Site 1 core be used to test the hypothesis that a shift in elemental ratio concentrations at 120 cmbsf marks the Pleistocene/Holocene boundary? 2) Is there evidence of turbidity flow deposition at STEMSEAS Site 1? 3) Can the foraminiferal assemblages within STEMSEAS Site 1 core be used to study paleoenvironmental changes in the California Borderland through time? Thirty-four samples of the \u3e63 mm size sediment fraction from the core were analyzed throughout this study, and the data from those samples was compared with lithologic and elemental data collected by the STEMSEAS cruise shipboard party and with regional data. Additionally, radiocarbon dates were obtained to develop an age model for the core, which allowed cored data to be interpreted in a temporal context. In answering the proposed questions, the study found that: 1) The shift in elemental data at 120 cmbsf occurs very close to (~1 kyr following) the Pleistocene/Holocene boundary, and the Pleistocene/Holocene transition represents a period of low dissolved oxygen supply within the Tanner Basin and low surface productivity. 2) A small percentage of benthic foraminifera present at Site 1 were displaced to Site 1 from a shallower depth, suggesting that turbidity flows did impact sedimentation at this location, but were not the dominant sediment transport process. 3) The core records a paleoenvironmental history of semi-regular millennial scale variation in sea surface temperature, upwelling strength, and nutrient influx that may be driven by oscillating and increasing frequency of El Niño/Southern Oscillation events

The environment effect on operation of in-vessel mirrors for plasma diagnostics in fusion devices

First mirrors will be the plasma facing components of optical diagnostic systems in ITER. Mirror surfaces will undergo modification caused by erosion and re-deposition processes [1,2]. As a consequence, the mirror performance may be changed and may deteriorate [3,4]. In the divertor region it may also be obscured by deposition [5-7]. The limited access to in-vessel components of ITER calls for testing the mirror materials in present day devices in order to gather information on the material damage and degradation of the mirror performance, i.e. reflectivity. A dedicated experimental programme, First Mirror Test (FMT), has been initiated at the JET tokamak within the framework Tritium Retention Studies (TRS).Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France).Submitted by B. Schunke on behalf of V. Voytseny

On the Prospects of Using Metallic Glasses for In-vessel Mirrors for Plasma Diagnostics in ITER

This chapter reviews main results obtained on mirror-like samples made of several grades of bulk metallic glasses (BMG). Experiments were carried out under simulated conditions typical for the operation of plasma facing in-vessel mirrors of optical plasma diagnostics in fusion reactor ITER. Bombardment with D0 and T0 atoms radiated from burning plasma was predicted to be the main reason for the degradation of optical properties of such mirrors. Therefore, to simulate the behavior of mirrors in ITER, mirror-like samples were subjected to bombardment by ions of deuterium plasma with fixed or wide energy distribution. The effects of ion bombardment on optical properties, development of roughness, uptake of deuterium, appearance of blisters, and manifestation of some chemical processes are presented and discussed