Novel attitude control devices for CubeSat satellites

In recent years a very modern trend of space exploration activities – constructing, launching and operating nano-satellites, became very popular. One of the main problems in implementation and control of nano-satellite is ensuring accurate yet simple and small-sized attitude control equipment. Most of the equipment implemented for that task in the past was large, bulky and could be hardly used on extremely small CubeSat standard nano-satellites. The equipment under development for attitude control of the satellites is described in this paper. The equipment relies on implementation of piezoelectric transducers for rotation of spherical body – reaction sphere, thus ensuring precise three-axis attitude control of the satellite by means of single device. Description of the device under development with some calculations and examples of implementation of such instrumentation is further described in the paper

Antrinės spinduliuotės žadinimas aukšto intensyvumo lazeriniais laukais ir jos taikymas medžiagotyroje

In this thesis, the properties of electron beams and secondary X-ray radiation using high-intensity Laser Plasma Wakefield Accelerators (LWFA) and structured plasma concentration profiles in wiggler and injector geometry were studied. The energy and divergence of LWFA electron beams using Particle-in-Cell FBPIC code were numerically simulated. The results were post-processed for the estimation of the parameters of secondary betatron X-ray radiation. The supersonic gas jets of micronozzle arrays required the formation of plasma concentration profiles were modelled using OpenFOAM software of computational fluid dynamics. The micronozzle arrays were manufactured from fused silica using hybrid nanosecond laser rear-side machining and femtosecond laser-assisted selective etching (FLSE) technique. The experimental work was done using the 40 TW, 35 fs laser at the Lund Laser Centre. Using nozzle arrays in injector geometry and combined density down-ramp and ionization injection, quasi-monoenergetic electron bunches of 4-5 pC and 50±10 MeV were generated. The implementation of the betatron source with structured plasma concentration profiles in wiggler geometry raised the efficiency of X-ray generation and increased the number of photons per shot by a factor of 2 - 3 compared to a single-jet gas target. Electron energies of 30-150 MeV and 1.0×108 -5.5×108 photons per shot of betatron radiation have been measured

Laser wakefield accelerated electron beams and betatron radiation from multijet gas targets

Laser Plasma Wakefield Accelerated (LWFA) electron beams and efficiency of betatron X-ray sources is studied using laser micromachined supersonic gas jet nozzle arrays. Separate sections of the target are used for the injection, acceleration and enhancement of electron oscillation. In this report, we present the results of LWFA and X-ray generation using dynamic gas density grid built by shock-waves of colliding jets. The experiment was done with the 40 TW, 35 fs laser at the Lund Laser Centre. Electron energies of 30–150 MeV and 1.0 × 108–5.5 × 108 photons per shot of betatron radiation have been measured. The implementation of the betatron source with separate regions of LWFA and plasma density grid raised the efficiency of X-ray generation and increased the number of photons per shot by a factor of 2–3 relative to a single-jet gas target source

Carrier-envelope phase controlled dynamics of relativistic electron beams in a laser-wakefield accelerator

International audienceIn laser-wakefield acceleration, an ultra-intense laser pulse is focused into an underdense plasma to accelerate electrons to relativistic velocities. In most cases, the pulses consist of multiple optical cycles and the interaction is well described in the framework of the ponderomotive force where only the envelope of the laser has to be considered. But when using single-cycle pulses, the ponderomotive approximation breaks down, and the actual waveform of the laser has to be taken into account. In this paper, we use nearsingle-cycle laser pulses to drive a laser-wakefield accelerator. We observe variations of the electron beam pointing on the order of 10 mrad in the polarization direction, as well as 30% variations of the beam charge, locked to the value of the controlled laser carrier-envelope phase, in both nitrogen and helium plasma. Those findings are explained through particle-in-cell simulations indicating that low-emittance, ultrashort electron bunches are periodically injected off-axis by the transversally oscillating bubble associated with the slipping carrier-envelope phase