Evaluation of flux expulsion and flux trapping sensitivity of srf cavities fabricated from cold work Nb sheet with successive heat treatment

The main source of RF losses leading to lower quality factor of superconducting radio-frequency cavities is due to the residual magnetic flux trapped during cool-down. The loss due to flux trapping is more pronounced for cavities subjected to impurities doping. The flux trapping and its sensitivity to rf losses are related to several intrinsic and extrinsic phenomena. To elucidate the effect of re-crystallization by high temperature heat treatment on the flux trapping sensitivity, we have fabricated two 1.3 GHz single cell cavities from cold-worked Nb sheets and compared with cavities made from standard fine-grain Nb. Flux expulsion ratio and flux trapping sensitivity were measured after successive high temperature heat treatments. The cavity made from cold worked Nb showed better flux expulsion after 800 C/3h heat treatments and similar behavior when heat treated with additional 900 C/3h and 1000 C/3h. In this contribution, we present the summary of flux expulsion, trapping sensitivity, and RF results.Comment: 21st International Conference on Radio-Frequency Superconductivity (SRF 2023

Quench Detection in a Superconducting Radio Frequency Cavity with Combine Temperature and Magnetic Field Mapping

Local dissipation of RF power in superconducting radio frequency cavities create so called hot spots, primary precursors of cavity quench driven by either thermal or magnetic instability. These hot spots are detected by a temperature mapping system, and a large increase in temperature on the outer surface is detected during cavity quench events. Here, we have used combined magnetic and temperature mapping systems using anisotropic magnetoresistance (AMR) sensors and carbon resisters to locate the hot spots and areas with high trapped flux on a 3.0 GHz single-cell Nb cavity during the RF tests at 2.0 K. The quench location and hot spots were detected near the equator when the residual magnetic field in the Dewar is kept < 1 mG. The hot spots and quench locations moved when the magnetic field is trapped locally, as detected by T-mapping system. No significant dynamics of trapped flux is detected by AMR sensors, however, change in magnetic flux during cavity quench is detected by a flux gate magnetometer, close to the quench location. The result provides the direct evidence of hot spots and quench events due to localized trapped vortices.Comment: 21st International Conference on Radio-Frequency Superconductivity (SRF 2023

Productivity and Profitability Assessment of Drought Tolerant Rice Cultivars under Different Crop Management Practices in Central Terai of Nepal

Reduction in productivity has led to lower profitability of rice production in Nepal. Proper selections of resource conservation technologies and drought tolerant cultivars are being potential strategies determining productivity of rice in drought prone areas. Thus, a field experiment was accomplished in central-terai of Nepal during 2014 to assess the productivity and profitability of drought tolerant rice cultivars under different crop management practices. The experiment was carried out in strip-plot design with three replications consisting four drought tolerant rice cultivars and three crop management practices. The analyzed data revealed that SRI (System of Rice Intensification) produced significantly higher grain yield (5.28 t ha-1) than other management practices. The straw yield of SRI (5.12 t ha-1) was also significantly higher than other management practices. The cultivars had no influence on grain yield, but the straw yield was significantly influenced by cultivars, with the highest straw yield in Sukkha-3 (5.21 t ha-1). Similarly, SRI management practice also had significantly higher gross returns (NRs. 144652 ha-1), net return (NRs. 56647 ha-1) and B:C ratio (1.64:1). Thus, SRI management practice can be adopted as adaptation approach for obtaining higher productivity and profitability in central terai and similar agro-climatic regions of Nepal

Assessment of Yield and Yield Attributing Characters of Hybrid Maize using Nutrient Expert® Maize Model in Eastern Terai of Nepal

Indiscriminate use of fertilizer and lack of site specific nutrient management technology is the main cause of low maize productivity in Nepal. Thus, field experiments on farmer\u27s field were conducted on maize to assess the productivity at two sites of Jhapa district viz. Damak and Gauradaha using Nutrient Expert® Maize model from November 2015 to May 2016. The experiment was laid out in Randomized Completely Block Design consisting two treatments viz. NE (Nutrient Expert recommendation) and FFP (Farmer\u27s Fertilizer Practice) with twenty replications. The result revealed significant differences in terms of grain yield, stover yield, biological yield, and yield attributing characters. NE based practices produced higher grain yield (9.22 t ha-1), which was 86.6 percent higher than FFP (4.94 t ha-1). Similarly, higher average cob number m 2 (8.2), average kernel rows cob-1 (14.2), average kernels number row-1 (589.9) and test weight (361.4 g) were recorded in NE based practice. Thus, NE based practice can be adopted for obtaining higher productivity in eastern terai region of Nepal

Participatory research approaches rapidly improve household food security in Nepal and identify policy changes required for institutionalisation

The introduction, testing, promotion and release of a rice variety, BG 1442, in Nepal were examined in relation to existing policies governing these procedures and to how more participatory approaches could benefit food security. From 1998 to 2006, participatory varietal selection (PVS) was used to test BG 1442 and other candidate rice varieties in the spring (Chaite) rice-growing season (February to June) and in the main season (June to November). The testing of BG 1442 commenced 11 years after it was first introduced into Nepal in 1987 by the national rice research programme (NRRP). Following its initial acceptance by farmers, it was widely disseminated from 1998 by non-governmental organisations (NGOs) in the low altitude region of Nepal called the terai in projects funded by the Department for International Development (DFID), UK. This dissemination was done using a method termed informal research and development (IRD) where many small packets of seed were distributed without fertiliser or pesticides, the only additional input being a description of varietal characteristics on an enclosed leaflet. From 2001 to 2008, various assessments were made of its extent of adoption and its impact on livelihoods. In a randomised survey of households in 10 districts, BG 1442 increased from not being used at all in 1997 to being grown by about 20% of the surveyed rice farmers by 2008. It was grown both in the Chaite and the main season and was well adapted to the rainfed-upland and medium-land rice ecosystems. The variety was grown from the far west to the far east of low-altitude Nepal by resource-poor farmers. IRD was important in accelerating adoption and improving food security as it was by far the most important external source of seed for farmers. Prior to the adoption of BG 1442, farmers who did not harvest sufficient rice to last their households for 12 months increased rice self sufficiency by over 2 months (25% more). Those households that sold surplus grain and who grew BG 1442 increased grain sales by 600 kg (25% more) in the Chaite season and by 370 kg (24% more) from main season cultivation

Quasi-normal modes of Schwarzschild-de Sitter black holes

The low-laying frequencies of characteristic quasi-normal modes (QNM) of Schwarzschild-de Sitter (SdS) black holes have been calculated for fields of different spin using the 6th-order WKB approximation and the approximation by the P\"{o}shl-Teller potential. The well-known asymptotic formula for large $l$ is generalized here on a case of the Schwarzchild-de Sitter black hole. In the limit of the near extreme $\Lambda$ term the results given by both methods are in a very good agreement, and in this limit fields of different spin decay with the same rate.Comment: 9 pages, 1 ancillary Mathematica(R) noteboo

Complex-valued Burgers and KdV-Burgers equations

Spatially periodic complex-valued solutions of the Burgers and KdV-Burgers equations are studied in this paper. It is shown that for any sufficiently large time T, there exists an explicit initial data such that its corresponding solution of the Burgers equation blows up at T. In addition, the global convergence and regularity of series solutions is established for initial data satisfying mild conditions

Building Strong Primary Health Care to Tackle the Growing Burden of Non-Communicable Diseases in Nepal

Nepal is currently facing a double burden of non-communicable diseases (NCDs) and communicable diseases, with rising trends of NCDs. This situation will add great pressure to already fragile health systems and pose a major challenge to the country’s development unless urgent action is taken. While the primary health care approach offers a common platform to effectively address NCDs through preventive and curative interventions, yet its potential is not fully tapped in Nepal. In line with the Alma-Ata and Astana declarations, we propose an integrated approach for Nepal, and other low-and middle-income countries, including six key reforms to enhance the primary care response to the increasing burden of NCD

Temperature, RF Field, and Frequency Dependence Performance Evaluation of Superconducting Niobium Half-Wave Coaxial Cavity

Recent advancement in superconducting radio frequency cavity processing techniques, with diffusion of impurities within the RF penetration depth, resulted in high quality factor with increase in quality factor with increasing accelerating gradient. The increase in quality factor is the result of a decrease in the surface resistance as a result of nonmagnetic impurities doping and change in electronic density of states. The fundamental understanding of the dependence of surface resistance on frequency and surface preparation is still an active area of research. Here, we present the result of RF measurements of the TEM modes in a coaxial half-wave niobium cavity resonating at frequencies between 0.3 - 1.3 GHz. The temperature dependence of the surface resistance was measured between 4.2 K and 1.6 K. The field dependence of the surface resistance was measured at 2.0 K. The baseline measurements were made after standard surface preparation by buffered chemical polishing