X-shooter is a new high-efficiency spectrograph observing the complete spectral range of 300-2500 nm in a single exposure, with a spectral resolving power R>5000. The instrument will be located at the Cassegrain focus of one of the VLT UTs and consists of three spectrographs: UV, VIS and Near-IR. This paper addresses the design, hardware realization and performance of the Near-IR spectrograph o...

Joule-Thomson cooling systems are used in refrigeration processes such as cryogenic gas liquefaction. Although extensive studies have been carried out by researchers, most of them include cryogenic heat exchangers and their associated fields. In the current study, an attempt was made to indicate the effect of using inappropriate operational conditions in a cryogenic Joule-Thomson cooling system...

Heat exchangers are the most important equipment in refrigeration processes. Design and modeling of heat exchangers operating at low temperatures are different from other regular heat exchangers. This study includes two sections. In the first section, design and modeling considerations needed for evaluating the real thermal behavior of heat exchangers at low temperatures were discussed. The...

The deep cryogenic treatment is a complementary operation that is done on a variety of tool steels aimed at improving their abrasion resistance and hardness. In the case of the H13 hot-work steel, which is widely used at high temperatures as a hot-deformation tool, we need to determine the efficiency of subzero treatment on it at the working temperature. In this regard, this paper is focu...

Short channel MOSFET devices have been fabricated using a commercial 0.25 μm CMOS process and characterized at cryogenic temperatures for further application in hybrid superconductor-CMOS circuits. A 4 K device model has been established through modifying the room temperature CMOS model by taking into account the parameter variation of the discrete MOS devices at cryogenic temperature. We have ...

The ATLAS magnet system, comprising a superconducting central solenoid and three superconducting toroids, has been successfully ramped up for the first time to the nominal operational current of 20.4 kA on 4 th August 2008. Since then, new cryogenic operational challenges have been raised, like the smoothing of steady-state parameters, the enhancing of transient procedures to minimize thermal s...

An experimental evaluation of the structural health monitoring capability of piezoelectric wafer active sensors on composite structures at cryogenic temperatures is presented. The piezoelectric wafer active sensor–based electromechanical impedance and the pitch–catch methods were first qualified for cryogenic temperatures using piezoelectric wafer active sensor–instrumented composite specimens ...

The superconducting Tevatron accelerator at Fermi National Accelerator Laboratory (Fermilab) has surpassed twenty years of operation. The Tevatron is still the highest energy particle accelerator in the world and will remain so until the commissioning of the LHC in Europe later this decade. The Tevatron has operated in a Fixed Target mode, accelerating a proton beam into stationary targets/dete...

Preliminary note The industry is under increasing pressure of the financial crisis, global competition, stricter environmental legislation and supply-chain demand. To tackle these issues, a sustainable development trend has to be assured synergetically on all the levels/fields, including machining processes. This paper promotes sustainable production via an improvement of machining technologies...

Charging mechanism of dust particles in a nonuniform discharge plasma under cryogenic environment is studied theoretically. The plasma density and temperature effects on dust grain charging are investigated with characteristic time scales of density variation and temperature relaxation in consideration. The charge of a dust grain, initially placed in a discharge plasma and cooled to cryogenic t...