Particle accelerators represent an indispensable tool in science and industry. However, the size and cost of conventional radio-frequency accelerators limit the utility and reach of this technology. Dielectric laser accelerators (DLAs) provide a compact and cost-effective solution to this problem by driving accelerator nanostructures with visible or near-infrared pulsed lasers, resulting in a 104 reduction of scale. Current implementations of DLAs rely on free-space lasers directly incident on the accelerating structures, limiting the scalability and integrability of this technology. We present an experimental demonstration of a waveguide-integrated DLA that was designed using a photonic inverse-design approach. By comparing the measured electron energy spectra with particle-tracking simulations, we infer a maximum energy gain of 0.915 kilo–electron volts over 30 micrometers, corresponding to an acceleration gradient of 30.5 mega–electron volts per meter. On-chip acceleration provides the possibility for a completely integrated mega–electron volt-scale DLA.
Net acceleration of attosecond-scale electron pulses is critical to the development of on-chip accelerators. We demonstrate a silicon-based, laser-driven, two-stage accelerator as an injector stage prototype for a Dielectric Laser Accelerator (DLA). The first stage converts a 57 keV, 500 ± 100 fs (FWHM) electron pulse into a pulse train of 700 ± 200 as (FWHM) microbunches. The second stage harnesses the tunability of dual-drive DLA to perform both a net acceleration and a streaking measurement. In the acceleration mode, the second stage increases the net energy of the electron pulse by 200 eV over 12.25 µm. In the deflection mode, the microbunch temporal profile is analyzed by a direct streaking measurement with 200 as resolution. This work provides a demonstration of a novel, on-chip method to access the attosecond regime, opening new paths towards attosecond science using DLA.
We propose an on-chip optical power delivery system for dielectric laser accelerators based on a fractal 'tree-branch' dielectric waveguide network. This system replaces experimentally demanding free-space manipulations of the driving laser beam with chip-integrated techniques based on precise nano-fabrication, enabling access to orders of magnitude increases in the interaction length and total energy gain for these miniature accelerators. Based on computational modeling, in the relativistic regime, our laser delivery system is estimated to provide 21 keV of energy gain over an acceleration length of 192 µm with a single laser input, corresponding to a 108 MV/m acceleration gradient. The system may achieve 1 MeV of energy gain over a distance less than 1 cm by sequentially illuminating 49 identical structures. These findings are verified by detailed numerical simulation and modeling of the subcomponents and we provide a discussion of the main constraints, challenges, and relevant parameters in regards to on-chip laser coupling for dielectric laser accelerators.
Integration reforms have been piloted as key policies to address the fragmented health insurance system in China. They are also regarded as a better choice for realizing a Universal Basic Medical Insurance System (UBMIS). This study has attempted to explore the determinants that may affect respondents' dissatisfaction with the reforms. The aim is to provide evidence for more effective policy adjustment during the next round of nationwide integration reforms in China. A cross-sectional questionnaire survey was conducted in Ningbo, Chongqing and Heilongjiang from 2014 to 2015. A stratified cluster sampling method was adopted. A total of 1644 respondents, working in units related to health insurance, were selected. A multivariate logistic regression model was employed to identify any association between dissatisfaction and the features of the ongoing integration reforms of health insurance schemes. Overall, about 47.6% of the respondents reported dissatisfaction with the ongoing integration reforms. This high level of dissatisfaction was found to be associated with ineffective outcomes of the integration reforms in achieving management system improvement [odds ratio (OR) = 1.846], inequity reduction (OR = 1.464) and actual coverage expansion (OR = 1.350), as perceived by the respondents. Those who were satisfied with the previously separated health insurance schemes (OR = 0.643), and those who preferred other policy options for achieving a UBMIS (OR = 1.471) were more likely to report dissatisfaction with the current reforms. Higher expectations of the risk-pooling level (with ORs ranging from 1.361 to 1.661) also significantly contributed to dissatisfaction. Health insurance managers in China have conflicting opinions about the performance of piloted integration reforms. Many believe that these reforms have failed significantly to improve the management systems, narrow inequity and expand actual benefit coverage. Various strategies should be undertaken in order to address these issues, such as clarifying the administrative institution behind the merged schemes at the central level, unifying the insurance information network, developing consistent policies and bridging the differences in benefits among schemes and regions.
19The electrical and electronic equipment (EEE) industry has increased its mass production; 20 however, the EEE life span has similarly diminished. Owing to the rapid expansion of 21 manufacturing, innovation and consumer demand, there has been a vast improvement in 22 various electronic equipment, so the amount of waste electrical and electronic equipment 23 (WEEE, or e-waste) generated has also increased proportionally to production. The main 24 objective of this article is to evaluate the remanufacturing concept which can be adopt by the 25 electronic manufacturing industry. The article reveals differential steps debated by industry as 26 well as academia in assets to reduce the amount of e-waste. The concept of e-waste 27 remanufacturing is quite dissimilar from case studies among developing and developed 28 countries and regions. The findings can assist the academic research and leads to industry 29 regardless remanufacturing of used EEE or WEEE by exemplifying different methods and 30 ideologies of remanufacturing implementation plus the main issues in this field. 31
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