Summary Session 02-03: Shutdown 2012
Explore the source record for details and available documents.
CHAMONIX↗
SEARCH · Search NASA
Results for “CRYO MAINTENANCE”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Architecture of the chromatin remodeler RSC and insights into its nucleosome engagement
Eukaryotic DNA is packaged into nucleosome arrays, which are repositioned by chromatin remodeling complexes to control DNA accessibility. The Saccharomyces cerevisiae RSC (Remodeling the Structure of Chromatin) complex, a member of the SWI/SNF chromatin remodeler family, plays critical roles in genome maintenance, transcription, and DNA repair. Here, we report cryo-electron microscopy (cryo-EM) and crosslinking mass spectrometry (CLMS) studies of yeast RSC complex and show that RSC is composed of a rigid tripartite core and two flexible lobes. The core structure is scaffolded by an asymmetric Rsc8 dimer and built with the evolutionarily conserved subunits Sfh1, Rsc6, Rsc9 and Sth1. The flexible ATPase lobe, composed of helicase subunit Sth1, Arp7, Arp9 and Rtt102, is anchored to this core by the N-terminus of Sth1. Our cryo-EM analysis of RSC bound to a nucleosome core particle shows that in addition to the expected nucleosome-Sth1 interactions, RSC engages histones and nucleosomal DNA through one arm of the core structure, composed of the Rsc8 SWIRM domains, Sfh1 and Npl6. Our findings provide structural insights into the conserved assembly process for all members of the SWI/SNF family of remodelers, and illustrate how RSC selects, engages, and remodels nucleosomes.
59 BASIC BIOLOGICAL SCIENCES↗
25+2 poles, 4.3 T wiggler at BMIT – 7 years operational experience
The research program at the Biomedical Imaging and Therapy (BMIT) Facility at the Canadian Light Source (CLS) required a unique radiation source that would provide a wide beam fan with high critical energy and high dose rates. A superconductive wiggler was the only practical solution that could be installed inside the CLS ring. Design requirements were defined in 2005 [1-2]. The wiggler, optimized for a 3 GeV ring, was to match operating parameters of an equivalent hard X-ray source on a 6 GeV ring. Manufacturing started in 2006 and the wiggler was installed in November of 2007 [3-5]. Several modifications to external hardware and to the power supplies’ controls were implemented to address the air leaks into the He space and to provide the ability to change the field of the wiggler during normal operation without affecting other research groups. The original burst disk and pressure relief valves were replaced with commercial units. Most of the buna O-rings were replaced with metal O-rings, helping to provide air-tightness of external connections. Over the years, the nominal, no-load temperatures went up by 0.3 K at the LHe space and up by 4 K at the 50 K shield space due to deterioration of thermal links and insulation, resulting from thermal cycling and vibrations generated by cryo-coolers. In October of 2014 the wiggler went through major maintenance to improve the thermal links operation, to improve the LHe transfer line connection, to install additional heaters to mitigate potential ice growth, and to provide a separate exhaust path for the rupture disk port.
43 PARTICLE ACCELERATORS↗
Lunar Superconducting Magnetic Energy Storage (LSMES)
Superconducting Magnetic Energy Storage (SMES) is an energy storage system that stores electrical energy in the form of a magnetic field by passing direct current through a superconducting coil. The conductor for carrying the current operates at cryogenic temperatures where it becomes a superconductor and thus has virtually no resistive losses as it produces the magnetic field. [1]. The energy can be stored in a persistent mode until required [2]. The main terrestrial challenge for SMES is the need for a cryo-cooling system and the cost associated with its deployment, operation and maintenance. For lunar and planetary exploration, this challenge is totally mitigated using the cold environment of the mission to sustain superconductivity temperatures. The permanently shadowed craters on the moon have regolith temperatures between 50-60K (3), which is the operating temperature for High Temperature Superconducting (HTS) wire. SMES provides several ad-vantages over traditional chemical batteries that: 1) incur much energy loss in extremely cold environments due to power needed for heaters, 2) are inefficient due to their inherent redox and side reactions, and 3) fail over time due to charge/discharge cycling changes in their chemical processes.
Evans, M. E.↗
Pantechnik new superconducting ion source: PantechniK Indian Superconducting Ion Source
The new ECR ion source PantechniK Indian Superconducting Ion Source (PKISIS) was recently commissioned at Pantechnik. Three superconducting coils generate the axial magnetic field configuration, while the radial magnetic field is done with the multi-layer permanent magnets. Special care was devoted to the design of the hexapolar structure, allowing a maximum magnetic field of 1.32 T at the wall of the 82 mm diameter plasma chamber. The three superconducting coils using low temperature superconducting wires are cooled by a single double stage cryo-cooler (4.2 K). Cryogen-free technology is used, providing reliability and easy maintenance at low cost. The maximum installed RF power (18.0 GHz) is of 2 kW. Metallic beams can be produced with an oven (T{sub max}= 1400 deg. C) installed with an angle of 5 deg. with respect to the source axis or a sputtering system, mounted on the axis of the source. The beam extraction system is constituted of three electrodes in accel-decel configuration. The new source of Pantechnik is conceived for reaching optimum performances at 18 GHz RF frequencies. PKISIS magnetic fields are 2.1 T axial B{sub inj} and 1.32 T radial field in the wall, variable B{sub min} with an independent coil and a large and opened extraction region. Moreover, PKISIS integrates modern design concepts, like RF direct injection (2 kW availability), dc-bias moving disk, out-of-axis oven and axial sputtering facility for metal beams. Finally, PKISIS is also conceived in order to operate in a high-voltage platform with minor power consumption.
43 PARTICLE ACCELERATORS↗
Polymer–inorganic solid–electrolyte interphase for stable lithium metal batteries under lean electrolyte conditions
The solid-electrolyte interphase (SEI) is pivotal in stabilizing lithium metal anodes for rechargeable batteries. However, the SEI is constantly reforming and consuming electrolyte with cycling. The rational design of a stable SEI is plagued by the failure to control its structure and stability. In this article, we report a molecular-level SEI design using a reactive polymer composite, which effectively suppresses electrolyte consumption in the formation and maintenance of the SEI. The SEI layer consists of a polymeric lithium salt, lithium fluoride nanoparticles, and graphene oxide sheets, as evidenced by cryo-TEM, AFM, and surface-sensitive spectroscopies. This structure is different from that of a conventional electrolyte-derived SEI and has excellent passivation properties, homogeneity, and mechanical strength. The use of the polymer-inorganic SEI enables high-efficiency Li deposition and stable cycling of 4V Li|LiNi 0.5 Co 0.2 Mn 0.3 O 2 cells under lean electrolyte, limited Li excess, and high capacity conditions. The same approach was also applied to design stable SEI layers for sodium and zinc anodes.
25 ENERGY STORAGE↗
Katanin spiral and ring structures shed light on power stroke for microtubule severing
Microtubule-severing enzymes katanin, spastin and fidgetin are AAA ATPases critical for the biogenesis and maintenance of complex microtubule arrays in axons, spindles and cilia. Because of a lack of 3D structures, their mechanism has remained poorly understood. We report the first X-ray structure of the monomeric AAA katanin module and cryo-EM reconstructions of the hexamer in two conformations. These reveal an unexpected asymmetric arrangement of the AAA domains mediated by structural elements unique to severing enzymes and critical for their function. Our reconstructions show that katanin cycles between open spiral and closed ring conformations, depending on the ATP occupancy of a gating protomer that tenses or relaxes inter-protomer interfaces. Cycling of the hexamer between these conformations would provide the power stroke for microtubule severing.
59 BASIC BIOLOGICAL SCIENCES↗
FRIB Cryogenic Distribution System and Status
The MSU-FRIB cryogenic distribution system supports the 2 K primary, 4 K primary, and 35 - 55 K shield operation of more than 70 loads in the accelerator and the experimental areas. It is based on JLab and SNS experience with bayonet-type disconnects between the loads and the distribution system for phased commissioning and maintenance. The linac transfer line, which features three separate transfer line segments for additional independence during phased commissioning at 4 K and 2 K, connects the folded arrangement of 49 cryomodules and 4 superconducting dipole magnets and a fourth transfer line supports the separator area cryo loads. The pressure reliefs for the transfer line process lines, located in the refrigeration room outside the tunnel/accelerator area, are piped to be vented outdoors. The transfer line designs integrate supply and return flow paths into a combined vacuum space. The main linac distribution segments are produced in a small number of standard configurations; a prototype of one such configuration has been fabricated at Jefferson Lab and has been installed at MSU to support testing of a prototype FRIB cryomodule.
Ganni, Venkatarao↗
Liquid hydrogen pump performance and durability testing through repeated cryogenic vessel filling to 700 bar
Here, this paper reports the results of a comprehensive test of liquid hydrogen (LH 2 ) pump performance and durability conducted while cycle testing a prototype thin-lined cryogenic pressure vessel 456 times to 700 bar. This extensive LH2 pump experimental data set provides a wealth of information vital for a complete evaluation of the future potential of this promising technology for ambient temperature and cryo-compressed vessel refueling. The experiment was conducted at Lawrence Livermore National Laboratory (Livermore, CA)'s hydrogen test facility, specifically built for this experiment and including a containment vessel for safe testing of the prototype vessel and a control room for efficient monitoring. Original pump and storage instrumentation was complemented with an electric power analyzer and a boil-off mass flow meter for more complete pump characterization. The results of the experiment confirm most of the expected virtues of the LH 2 pump: rapid (3 min) refueling of the 65-liter prototype vessel at high flow rate (1.55 kgH 2 per minute on average), unlimited back to back refueling, low electricity consumption (1.1 kWh/kg H 2 ), no measurable degradation, and low maintenance. High cryogenic vessel fill density is another key performance metric that was demonstrated in an earlier publication. These virtues derive from the high density of LH 2 enabling pressurization to high density with relatively little energy consumption and high throughput from a small displacement pump. Boil-off losses as high as 27.7% of dispensed hydrogen were measured, at experimental conditions not representative of operation at a hydrogen refueling station. These losses drop to 15.4% for operation that may be representative of a small station (332 kg/day), while we anticipate less than 6% boil-off with the existing pump and Dewar with improved LH 2 delivery truck operations and a more favorable arrangement of the LH 2 pump relative to the Dewar.
08 HYDROGEN↗
Integrated Insulation System for Cryogenic Automotive Tanks (iCAT)
The objective of this project was to develop a state-of-the-art Integrated Insulation System for Cryogenic Automotive Tanks (iCAT) using new lightweight, commercially available materials applied with innovative methods that could demonstrate the DOE heat leak targets (< 5-7 W) for a 100 liter (L) cryogenic hydrogen storage tank and require little to no periodic maintenance. The project team focused on developing an integrated system based on a degraded vacuum (from 0.001 torr up to 0.1 torr) environment [Moderate Vacuum], and compared this system to the standard multi-layer insulation (MLI) high vacuum (HV) environment (< 10E-4 torr).
08 HYDROGEN↗