CERN SPS electron cloud heat load measurements and simulations

A calorimeter, WAMPAC, operating at room temperature has been designed and installed into the SPS to measure directly the electron cloud induced heat load due to the Large Hadron Collider (LHC)-type proton beam. Theoretical behavior, calibrations, measurement protocols, preliminary results, and simulation benchmarking are presented. Scaling of the results to the LHC indicated a linear heating power in a LHC dipole of about 500  mW m^{-1} for 5×10^{10}   protons/bunch^{-1} for a copper surface which is not fully conditioned (maximum of secondary electron yield ∼1.9)

Industrial Surfaces Behaviour Related to the Adsorption and Desorption of Hydrogen at Cryogenic Temperature

The determination of the hydrogen adsorption capacity on different industrial surfaces has been carried out by measuring isothermal adsorption. First results show that the adsorption capacity is mainly determined by surface porosity. Therefore, the samples may be classified in two categories: smooth surfaces and porous surfaces. Thermal desorption spectra reveal two adsorption energy levels for hydrogen physisorbed on porous materials, but only a single one on smooth samples. The value of the lowest energy level seems to be independent on the substrate nature. The physisorption process studied at low coverage, well below a monolayer, shows that these two levels are not well defined but an energy distribution exists for each of them.The influences of the isotherm temperature and an annealing at 7 K of an adsorbed monolayer on hydrogen adsorption capacity have been studied

Characterisation of net type thermal insulators at 1.8 K low boundary temperature

The Large Hadron Collider's superconducting magnets are cooled by superfluid helium at 1.8 K and housed in cryostats that minimise the heat inleak to this temperature level by extracting heat at 70 and 5 K. In the first generation of prototype cryostats, the radiative heat to the 1.8 K temperature level accounted for 70 % of the total heat inleak. An alternative to enhance the cryostat thermal performance incorporates a thermalised radiation screen at 5 K. In order to avoid contact between the 5 K radiation screen and the cold mass, insulators are placed between both surfaces. Sets of commercial fibre glass nets are insulator candidates to minimise the heat inleak caused by a accidental contact between the two temperature levels. A model to estimate their performance is presented. A set-up to thermally characterise them has been designed and is also described in the paper. Finally, results as a function of the number of the spacer nets, the boundary temperatures and the compressive force in the spacer are presented

Precise wide range heatmeters for 1.5 K up to 80 K

Two heatmeters were designed at CERN for applications below 20 K with the option to work also at temperatures up to 80 K. The new calibration principle and design permits the construction of wide rang e heatmeters with precision in the range of milliwatts. The calibration function takes into account the temperature dependence of the thermal conductivity of the heatmeter material. The heat flow meas urement is, therefore, independent of the base temperature, i.e. it is also independent on the temperature drop across thermal contact between heatmeter and the cold source. The simple calibration fun ction makes the heatmeter a user-friendly portable diagnostic device. It is possible to quantify parasitic heat flow without a previous calibration, or to calibrate the heatmeter during a measurement with a specimen

Cryosorber Studies for the LHC Long Straight Section Beam Screens with COLDEX

The cold bore experiment (COLDEX), that can be cooled below 3 K, has been fitted with a ~ 2 m long actively cooled beam screen equipped with cryosorber to simulate the LHC Long Straight Section (LSS) beam screens. Effects of both synchrotron radiation at grazing incidence with 194 eV critical energy and gas injections have been studied. Results as a function of temperature, gas species and gas coverage are presented. Possible implications to LHC LSS design and operation are discussed

First Results from COLDEX Applicable to the LHC Cryogenic Vacuum System

A cold bore experiment (COLDEX) has been installed in the electron-positron accumulator (EPA) at CERN. The ~2 m long COLDEX cryostat, that may be cooled to below 3 K, is fitted with an actively cooled perforated beam screen to simulate the conditions in the cold arcs of the LHC. Initially, gas desorption yields were obtained using an external synchrotron radiation beam line by exposing the beam screen to grazing incident radiation with a critical energy of 194 eV. In an extended period of EPA operation and during a dedicated period for LHC studies, COLDEX was installed into the EPA ring to study more specifically the influence of the bunched positron and electron beams with the cold bore / beam screen vacuum system. The results from these experiments and some predictions applicable for the LHC will be presented

Synchrotron radiation studies of the LHC dipole beam screen with COLDEX

The cold bore experiment (COLDEX) installed in a beam line of the electron-positron accumulator (EPA) at CERN, has been used to study the effect of synchrotron radiation onto the LHC dipole beam screen. The ~ 2 m long cryostat, that can be cooled below 3 K, is fitted with an actively cooled beam screen. A 'sawtooth' copper co-laminated type beam screen has been submitted to grazing synchrotron radiation with 194 eV critical energy. Experiments studying the effect of photon dose, gas condensation onto beam screen or cold bore and temperature oscillations is presented. Implications to LHC operation is discussed

Comparison of floating and thermalized multilayer insulation systems at low boundary temperature

The Large Hadron Collider (LHC) is 26.7 km circumference particle collider using high-field superconducting magnets operating in superfluid helium. An efficient and robust thermal insulation system is therefore required to minimize the residual heat in leak to the large surface area at 1.9 K constituted by the stainless steel wall of the helium enclosure. The baseline solution uses "floating" multilayer reflective insulation. Moreover, an alternative consists of a combination of multilayer reflective films and a soft screen, partially thermalized to the 5 K level and supported away from the cold wall by net-type insulating spacers. This chapter establishes the improvement potential of the alternative over the baseline solution, and compares their insulation performance on the basis of measured characteristics of thermal contacts and spacers

Research on Benefit Evaluation of Advanced Manufacturing Technology

先进制造技术投资是一项关系到企业生存与发展的战略投资，其投资质量对企业的技术实力，管理水平，经济效益，竞争能力和长远发展都会产生重大的影响。先进制造技术投资决策的质量在很大程度上取决于人们对其所做的技术经济评价质量，正如国内外专家学者在相关研究中所指出：“影响先进制造技术推广应用的关键原因，并不在于技术而在于管理，而且其中‘如何评价先进制造技术’是影响其应用的最主要原因。”本文首先阐述了先进制造技术项目方面国内外的相关文献，然后分析了先进制造技术的含义、特征与其效益评价目标、原则和方法，构建了经济效益评价、无形效益评价和投资风险评价的综合评价体系，该体系的主要框架为：（1）应用作业成本法思路，...Applying advanced manufacturing technology (AMT) to the enterprise is a really significant strategic investment for the continuous operation and development of company, and the quality of decision-making greatly impacts the technical strength, management quality level, economic efficiency, competitiveness and long-term development of a company. Moreover, the quality of AMT investment decision-maki...学位：管理学硕士院系专业：管理学院会计系_会计学学号：1752006115128