The results of design, simulation, and experimental testing of an electron-optical system with three elliptic electron beams are presented. Total beam current is 93 mA. The beams are focused by a PPM system with 0.55 T magnitude of the magnetic field. Beam transmission in a rectangular tunnel at over 25 mm distance is demonstrated. The developed electron optical system is assumed to be used in sub-THz-band vacuum-tube devices such as O-type traveling-wave tube or backward-wave oscillator. Electromagnetic parameters of a double-grating staggered slow-wave structure are calculated.
The report presents synthesis method of modeling the electron-focusing systems that formed compressed sheet electron beam with supporting the beam magnetic field and field-emission cathode. Results of calculating by synthesis and analysis method of the electron gun with linear compression of the beam 10, micro-perveance of Pμ = 0.035 and 100 mA current are performed. The electron gun forms a sheet beam with a 0.125mm thickness, and 0.7 mm width.
The results of simulation of electron-optical systems with sheet electron beam with compression are presented. Electron gun is considered with thermionic and field emission cathodes with 2.1 0.8 mm 2 . The result of modeling the electron gun at linear compression of 14, the beam of current 0.1 A has dimension of 0.15 0.8 mm 2 are performed. The electric field on the cold cathode is 0.16· 10 5 V/cm at anode voltage 20000 V.
For modern software systems, performance analysis can be a challenging task. The software stack can be a complex, multi-layer, multi-component, concurrent, and parallel environment with multiple contexts of execution and multiple sources of performance data. Although much performance data is available, because modern systems incorporate many mature data-collection mechanisms, analysis algorithms suffer from the lack of a unifying programming environment for processing the collected performance data, potentially from multiple sources, in a convenient and script-like manner.
This report presents the results of calculation of electron-optical system consisting of a sheet CNT field emission cathode with a microgrid spaced from the surface of the emitter at 100 microns. On the basis of experimental data, it has been designed electron-optical system with a sheet CNT cathode with linear convergence of 6,25, and with the beam current density of 4,46 A/cm 2 . The thickness of the beam in the interaction space is 0,16 mm. In this case, the simulation of the sheet electron beam, generated by electron gun has shown feasibility of obtaining of low-perveance flow with a small deformation in beam tunnel 0,3×0,8 at 25 mm slow-wave system length.
This article presents the results of a design study of an electron-optic system (EOS) for a sheet-beam G-band traveling-wave tube. An electron gun providing a 0.1-A, 20-kV sheet beam emitted by a 0.8 mm × 0.8 mm curved cylindrical cathode is designed. The beam dimensions at waist position are 0.05 mm × 0.8 mm with a compression ratio of 16 in the vertical direction. A magnetic system providing 1.1 T magnetic field, which is nearly seven times higher than the Brillouin field, is designed, and beam transmission in the 0.1 mm × 0.85 mm beam tunnel is studied by 3-D particle-in-cell (PIC) simulation. It is demonstrated that the beam has a complex structure of particle distribution, i.e., a high-density central part (core) and a peripheral low-density part (halo). The effect of assembly tolerance on beam transmission is studied. The prototype gun is fabricated, which compresses the beam to 0.1 mm by electrostatic field only. The 135-mA current with 95% transmission through the 0.2-mm anode aperture is measured.
A modern software system is a composition of parts that are themselves highly complex: operating systems, middleware, libraries, servers, and so on. In principle, compositionality of interfaces means that we can understand any given module independently of the internal workings of other parts. In practice, however, abstractions are leaky, and with every generation, modern software systems grow in complexity. Traditional ways of understanding failures, explaining anomalous executions, and analyzing performance are reaching their limits in the face of emergent behavior, unrepeatability, cross-component execution, software aging, and adversarial changes to the system at run time.
Deterministic systems analysis has a potential to change the way we analyze and debug software systems. Recorded once, the execution of the system becomes an independent artifact, which can be analyzed offline. The availability of the complete system state, the guaranteed behavior of re-execution, and the absence of limitations on the run-time complexity of analysis collectively enable the deep, iterative, and automatic exploration of the dynamic properties of the system.
This work creates a foundation for making deterministic replay a ubiquitous system analysis tool. It defines design and engineering principles for building fast and practical replay machines capable of capturing complete execution of the entire operating system with an overhead of several percents, on a realistic workload, and with minimal installation costs. To enable an intuitive interface of constructing replay analysis tools, this work implements a powerful virtual machine introspection layer that enables an analysis algorithm to be programmed against the state of the recorded system through familiar terms of source-level variable and type names. To support performance analysis, the replay engine provides a faithful performance model of the original execution during replay.
Efficient deterministic replay of whole operating systems is feasible and useful, so why isn't replay a default part of the software stack? While implementing deterministic replay is hard, we argue that the main reason is the lack of general abstractions for understanding and addressing the significant engineering challenges involved in the development of a replay engine for a modern VMM. We present a design blueprint---a set of abstractions, general principles, and low-level implementation details---for efficient deterministic replay in a modern hypervisor. We build and evaluate our architecture in Xen, a full-featured hypervisor. Our architecture can be readily followed and adopted, enabling replay as a ubiquitous part of a modern virtualization stack.
