[en] Cavity loss factor calculation is an important part of the total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the addition of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.

[en] The test IFA-503.2 is carried out against the background of the first loading (IFA-503.1) where the behaviour of standard WWER-440 fuel in comparison with PWR type fuel was investigated [1,2,3]. The results obtained in the first loading prompted a test with state-of-the-art WWER-440 fuel pellets produced by MSZ Elemash (Russia) with an improved technology. The main goal of this test is to generate representative data for different types of modified WWER-440 fuel with emphasis on densification as well as thermal performance, swelling and fission gas release. Three types of the modified UO₂ WWER-440 fuel pellets, selected from tentative produced lots, were loaded into 10 fuel rods. Two reference rods were fuelled with fresh PWR type pellets similar to those used in the previous loading. The lower cluster of IFA-503.2 comprises two PWR type fuel rods instrumented with ET and EF detectors, two WWER2 fuel type rods and two WWER1 fuel type rods fitted with ET, EF and PF sensors. The upper cluster consists of 4 WWER1 fuel rods equipped with 2 ET, 2 PF and 2 EF detectors, and 2 WWERO fuel (modified standard WWER-440 fuel) rods instrumented with ET, EF and PF detectors. The preliminary analysis of the measurements for the first irradiation period is presented in this report in comparison with some results obtained from the first loading (author) (ml)

[en] The main objective of the test in IFA-503.2 is to study the thermal mechanical behaviour of different types of modified WWER-440 fuel, with emphasis on densification at the beginning of irradiation and subsequent swelling as well as thermal performance and fission gas release with burnup. Three types of modified WWER-440 UO₂ fuel pellets, selected from tentative batches produced by MSZ Electrostal, were loaded into 10 fuel rods. Two reference rods were fuelled with fresh PWR specification pellets produced by IFE (Kjeller) similar to those tested in IFA-503.1. The test assembly, comprising two clusters, has been irradiated since March 1999. A re-calibration test carried out in July 2000 allowed a precise rod power determination. The test rods have been operated at an ALHR of about 20-26 kW/m in the lower cluster and 15-18 kW/m in the upper cluster. The average burnup achieved in the lower and upper clusters as of November 2000 were around 15 and 11 MWd/kg UO₂, respectively. The fuel rods are instrumented with ET, EF and PF detectors; most of them are working satisfactorily and providing information on thermal and mechanical behaviour. The measurements indicated that all three types of the modified WWER fuels exhibit improved densification properties. Since the beginning of irradiation the WWER-1 type fuel has shown better thermal and mechanical performance than the other types of WWER fuel. Analysis also proved that the behaviour of this WWER fuel type was close to the PWR fuel tested in IFA-503.1 and IFA-503.2. Some differences concerning the behaviour of solid PWR and hollow WWER fuel pellets have also been explored in the test. (Author)

[en] Details of wake potential simulation in the acceleration structure of ILC, including the RF cavities and input/HOM couplers are presented. Transverse wake potential dependence is described versus the bunch length. Beam emittance dilution caused by main and HOM couplers is estimated, followed by a discussion of possible structural modifications allowing a reduction of transverse wake potential

[en] IFA-503.2 has been irradiated since March 1999 with main objective to study the thermal and mechanical behaviour of different types of modified WWER-440 fuel compared with PWR reference fuel. 10 rods with three types of WWER-440 UO₂ fuel pellets produced by MSZ (Electrostal, Russia) and 2 reference rods with PWR pellets produced by IFE (Kjeller) are instrumented with ET, EF and PF detectors providing comparative information on irradiation performance of these fuel types. The results obtained during first stage of the test have indicated that all types of the modified WWER fuels exhibit improved densification properties compared to earlier tested WWER fuel. One of these fuels (denominated WWER-1) has shown best thermal and mechanical performance which is similar PWR reference fuel. As of February 2002 the average burnup achieved in the higher power rating rods was around 20 MWd/kg UO₂ .The updated results from the in-pile measurements and analysis are presented together with some fuel microstructural examinations carried out to increase the existent data base on fuel porosity distribution (in particular for WWER fuel) associated with irradiation-induced densification. Quantitative analysis of these data confirmed the effect of sub-micron porosity on in-pile fuel densification. (Author)

[en] Superconducting cavities with high operating Q will be installed in the Project-X, a superconducting linac, which is under development at Fermilab. Possibility of cavity design without HOM couplers considered. Rich spectrum of the beam and large number of cavities in ProjectX linac can result to resonance excitation of some high order modes with high shunt impedance. Under scope of study of High order modes damping the manipulation with HOM spectrum in cold linac is considered. Results of detuning HOM spectrum of 1.3 GHz cavities at 2K in Horizontal Test Station of Fermilab are presented. Possible explanation of the phenomena is discussed.

[en] The comparative WWER/PWR test in IFA-503.1 was commenced in July 1995 and successfully finished at the end of November 1998. The main objective of the test was generation of representative and comparative data of standard WWER-440 fuel fabricated at the 'MSZ' Electrostal (Russia) and PWR type fuel manufactured at IFE Kjeller (Norway). The test assembly comprised two clusters, each with 3 WWER rods and 3 PWR type rods. Eight rods with two types of fuel were instrumented with expansion thermometers, four rods were equipped with both fuel stack elongation detectors and pressure transducers. All sensors worked satisfactorily during the test. The average burnups achieved in the lower and upper clusters were around 25 and 20 MWd/kgUO₂, respectively. Some difference in densification of the two types of fuel was revealed during the first irradiation period. However, the fuel temperatures and commencement of fuel stack swelling were similar despite this fact. At the end of the test the rig was moved to a higher flux position in the HBWR core with the aim of promoting FGR and to compare the behaviour of the two types of fuel under higher power. Pressure measurements indicated a comparable low FGR (around 1 percent) in both types of rods. The centreline temperatures measured in the PWR rods were very close to the Halden FGR threshold whilst the WWER fuel temperatures were slightly lower. Despite the differences found in the behaviour of the two types of fuel during the test, the analysis of the in-pile data showed that these differences would not affect the fuel efficiency, at least, up to the burnup achieved in the test. It is supposed that these differences can be related to the fuel microstructure, in particular to the fuel grain and pore sizes (author) (ml)

[en] High intensity nanosecond laser pulses of different wavelengths are used to remove thin film silicon dioxide coatings from the silicon surface. Films as thick as 0.7 μm can be removed from the surface in one shot with very minor or no damage to the bare silicon surface. The accumulated effect of multiple-pulse irradiation is studied. It is found that multiple-pulse irradiation results in some reduction of the threshold for coating removal. However, the surface quality gets significantly worse with the increasing number of shots

[en] In the ILC project the required accelerating gradient is higher than 30 MeV/m. For current technology the maximum acceleration gradient in SC structures is determined mainly by the value of the surface RF magnetic field. In order to increase the gradient, the RF magnetic field is distributed homogeneously over the cavity surface (low-loss structure), and coupling to the beam is improved by introducing aperture 'noses' (reentrant structure). These features allow gradients in excess of 50 MeV/m to be obtained for a singe-cell cavity. Further improvement of the coupling to the beam may be achieved by using a TW SC structure with small phase advance per cell. We have demonstrated that an additional gradient increase by up to 46% may be possible if a π/2 TW SC structure is employed. However, a TW SC structure requires a SC feedback waveguide to return the few GW of circulating RF power from the structure output back to the structure input. The test cavity with the feedback is designed to demonstrate the possibility of achieving a significantly higher gradient than existing SC structures

[en] Scanning electron microscope Philips XL 30 ESEM - TMP with X-ray microanalysis system INCA has been installed at SSC RF RIAR. The microscope is placed in the hot cell. Monitoring and control system is installed in the operator's room. Irradiated specimens are supplied to the hot cell through the transport terminal and installed into the microscope by manipulators. Direct contact of the personnel with radioactive materials is impossible. In addition it is developed the system of remote placement of the irradiated specimens into the specimen chamber of microscope. The system includes a stage with three seats, holders for different types of specimens and equipment for their remote loading in the holders. (Author)