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Characterization of Noise in CMOS Ring Oscillators at Cryogenic Temperatures
Allan deviation provides a means to characterize the time-dependence of noise in oscillators and potentially identify the source characteristics. Measurements on a 130 nm, 7-stage ring oscillator show that the Allan deviation declines from 300 K to 150 K as expected, but surprisingly increases from 150 K to 11 K. At low temperatures, the measured Allan deviation can be well fit using a few random telegraph noise (RTN) sources over the range of a few kilohertz to a few gigahertz. Further, the RTN characteristics evolve to reveal an enhanced role in low-frequency noise at lower temperatures.
Cryogenic Temperature Properties and Secondary Phase Characterization of CuCrZr Composites
Not provided.
Nb$_{3}$Sn SRF Photogun High Power Test at Cryogenic Temperatures
Superconducting RF (SRF) photoguns are emerging as promising candidates to produce highly stable electrons for Ultra fast Electron Diffraction/Microscopy (EUD/UEM) applications due to the ultrahigh shot-to-shot stability compared to room temperature RF photoguns. SRF technology was prohibitively expensive for industrial use until two recent advancements: Nb 3 Sn and conduction cooling. SRF gun can provide a CW operation capability while consuming only several Watts of RF power which eliminates the need of an expensive high power RF system and saves a facility footprint. Euclid is developing a continuous wave (CW), 1.5-cell, MeV-scale SRF conduction cooled photogun operating at 1.3 GHz. Here, in this paper, we present first high power results of the gun covered with Nb 3 Sn.
Localized exciton emission from monolayer WS 2 nanoribbon at cryogenic temperature
Abstract We conducted low-temperature photoluminescence (PL) spectroscopy experiments on individual WS 2 and MoSe 2 nanoribbons prepared by gold-assisted exfoliation from the slanted surface of bulk crystals with a vicinal and stepwise pattern. The nanoribbons are predominantly monolayer and have widths varying from hundreds of nanometers down to tens of nanometers. Most MoSe 2 NRs display an emission profile similar to 2D excitons of MoSe 2 monolayers. In contrast, WS 2 nanoribbons are characterized with sharp emission peaks that can be attributed to the emission from localized excitons or trions. Moreover a broad low energy emission peak can be also observed from some of the WS 2 nanoribbons, which originates from bilayer regions. In this manuscript, we analyze spectral diffusion behavior along with pump power and temperature dependence of the localized exciton emission peaks, shedding light on potential of TMDC nanoribbons in sensing and opto-electronic applications.
First High-Gradient Results of UED/UEM SRF Gun at Cryogenic Temperatures
Benefiting from the rapid progress on RF photogun technologies in the past two decades, the development of MeV range ultrafast electron diffraction/microscopy (UED and UEM) has been identified as an enabling instrumentation. UEM or UED use low power electron beams with modest energies of a few MeV to study ultrafast phenomena in a variety of novel and exotic materials. SRF photoguns become a promising candidate to produce highly stable electrons for UEM/UED applications because of the ultrahigh shot-to-shot stability compared to room temperature RF photoguns. SRF technology was prohibitively expensive for industrial use until two recent advancements: Nb₃Sn and conduction cooling. The use of Nb₃Sn allows to operate SRF cavities at higher temperatures (4K) with low power dissipation which is within the reach of commercially available closed-cycle cryocoolers. Euclid is developing a continuous wave (CW), 1.5-cell, MeV-scale SRF conduction cooled photogun operating at 1.3 GHz. In this paper, we present first high gradient results of the gun conducted in liquid helium.
Electrical and Thermal Properties of Cold-Sprayed Bulk Copper and Copper-Tungsten Samples at Cryogenic Temperatures
The development of high thermal conductivity coatings with pure copper or copper-tungsten alloy could be beneficial to improve the heat transfer of bulk Nb cavities for conduction cooling applications and to increase the stiffness of bulk Nb cavities cooled by liquid helium. Cold-spray is an additive manufacturing technique suitable to grow thick coatings of either Cu or CuW on a Nb substrate. Bulk (~5 mm thick) coatings of Cu and CuW were deposited on standard 3 mm thick, high-purity Nb samples and smaller samples with 2 mm x 2 mm cross section were cut for measuring the thermal conductivity and the residual resistivity ratio. The samples were subjected to annealing at different temperatures and a maximum RRR of ~130 and ~40 were measured for the Cu samples and CuW samples, respectively.
Mitigation of Dielectric Heating of Piezoelectric Actuators at Cryogenic Temperatures
The new generation of low beam intensity superconducting linacs will require high accelerating gradients for new scientific discoveries. The high accelerating gradient cavities in pulsed SRF linacs will experience large (~1000’s of Hz) detuning caused by Lorentz force detuning (LFD). The piezo actuators that will be used to compensate large LFD must operate at a nominal voltage of 120V to 150V to deliver the required stroke to the cavity. In this high voltage range, the piezo is expected to warm up drastically due to its location in an insulating vacuum environment. Overheating of the piezo will significantly decrease the longevity of the actuator. A collaboration between FNAL and Physik Instrumente (PI) developed a novel piezo actuator design that mitigates piezo overheating. The design consists of using a metal foam in contact with the piezoelectric ceramic stack for heat removal. The second solution used lithium niobite as an alternative material. A comparison of the temperature stability will be presented and discussed. This study characterizes the dielectric properties for both materials. The results obtained are in the temperature range of 10 K to 300 K.
Electrical and Thermal Properties of Cold-Sprayed Bulk Copper and Copper-Tungsten Samples at Cryogenic Temperatures
The development of high thermal conductivity coatings with pure copper or copper-tungsten alloy could be beneficial to improve the heat transfer of bulk Nb cavities for conduction cooling applications and to increase the stiffness of bulk Nb cavities cooled by liquid helium. Cold-spray is an additive manufacturing technique suitable to grow thick coatings of either Cu or CuW on a Nb substrate. Bulk (~5 mm thick) coatings of Cu and CuW were deposited on standard 3 mm thick, high-purity Nb samples and smaller samples with 2 mm x 2 mm cross section were cut for measuring the thermal conductivity and the residual resistivity ratio. The samples were subjected to annealing at different temperatures and a maximum RRR of ~130 and ~40 were measured for the Cu samples and CuW samples, respectively.
Focused Ion Beam Characterization of Low Melting Point Metals at Cryogenic Temperatures.
Abstract not provided.
Research investigations of bulkhead cylindri- cal junctions exposed to combined load, cryogenic temperature. part iii- theoretical analysis of the thermal loads
Thermal stress in thin walled shell joint of missile intertank
Research Investigations of Bulkhead Cylindrical Junctions Exposed to Combined Load, Cryogenic Temperatures and Pressure. Part I - Experimental Studies
Two-dimensional analog model and 1/6 reduced scale model to study bending stress concentrations, strains, and displacements in Y-ring of Saturn V S-IV liquid oxygen container
Sandwich flexure tests at cryogenic temperature
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Superconducting switch permits measurement of small voltages at cryogenic temperatures
Dual-coil, superconducting, on-off switch measures small, thermoelectrically generated voltages produced by thermocouples in a liquid helium bath. Placed in a shunt configuration between the thermocouple and the measuring device, the measuring device sees the sum of the voltage to be measured and the spurious thermoelectric voltages.
Silicon strain sensors enable pressure measurement at cryogenic temperatures
Miniature pressure transducers with diffused, heavily doped silicon strain-gage sensor elements, operates over a wide temperature range. Small thermal mass combined with close coupling between a metallic diaphragm and sensor elements minimizes sensitivity to temperature transients.
Total emittance measurements of thin metallic films at cryogenic temperatures
Calorimetric measurements determining total hemispheric emittance of thin gold films as function of temperature, demonstrating film thickness effect
Thermal conductivity of aerospace alloys at cryogenic temperatures
Thermal conductivity, electrical resistivity, Lorentz ratio and thermopower of aerospace alloys in 4-300 K range, separating electronic and lattice contributions
Experimental investigations of desorption cooling methods at cryogenic temperatures Final report, May 1968 - Jun. 1970
Performance tests of low temperature desorption refrigeration systems with helium 4 and zeolite