Institute Of Plasma Physics And Laser Microfusion Research Articles

Study of plasma dynamics in the HET relying on global thruster characteristics parameterized with discharge voltage

A prototype of krypton Hall-effect thruster (HET) of 0.5 kW nominal power and a dedicated diagnostic system for ion current collection were designed in the laboratory of plasma space propulsion (PlaNS) of the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw. The diagnostic system consisting of a collimated Faraday Cup (FC) and a Planar Probe with Guarding Ring, named also Faraday Probe (FP) was intended to capture both temporal and spatial ion current variation, allowing to analyze not only ion current dynamics locally but also to estimate the total ion current value and a plasma jet divergence. Reliable engine operation provided by stability of plasma in a discharge channel of the thruster is unambiguously reflected in the oscillations of the discharge current. The so-called breathing mode, categorized as ionization instability with frequencies in the range of 10–30 kHz, is commonly recognized in the HET’s discharge current. Rising of instabilities makes it difficult to increase the specific impulse effectively by just simply attempting to operate thruster in high-voltage regime because it may result in very irregular thruster functioning and often to ceasing of plasma. Discharge current oscillations should also be strongly reflected in the ion current. Indeed, a similar to discharge current behavior was observed in the recorded FC and FP ion current signals. By changing thruster operating conditions, like discharge voltage and magnitude of B-field, transitions between smooth and oscillating current regimes were examined. Studying the ion current dynamics seems particularly important, since it is predicted that the control of discharge instabilities may be crucial to improve the performance of HETs in the future.

Plasma beam structure diagnostics in krypton Hall thruster

AbstractKrypton Large Impulse Thruster (KLIMT) project was aimed at incremental development and optimization of a 0.5 kW-class plasma Hall Effect Thruster in which, as a propellant, krypton could be used. The final thermally stable version of the thruster (the third one) was tested in the Plasma Propulsion Satellites (PlaNS) laboratory in the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw as well as in the European Space Agency (ESA) propulsion laboratory in the European Space Research and Technology Centre (ESTEC).During final measurement campaign, a wide spectrum of parameters was tested. The plasma potential, electron temperature, electron concentration, and electron energy probability function in the far-field plume of the thruster were measured with a single cylindrical Langmuir probe. Faraday probes were used for recording local values of ion current. Using several collectors in different locations and moving them on the surface of a sphere, the angular distribution of the expelled particles was reconstructed which was a local measure of beam divergence. Angular distribution of ion flux as measured with a central Faraday probe was parameterized with krypton mass flow rate, voltage, coil current ratio, and the cathode mass flow rate. Beam divergence measurements with Faraday probes as well as plasma parameters derived from Langmuir probe seem to be consistent with our understanding of the operating envelope. Obtained results will serve as a baseline in the design of plasma beam structure diagnostics system for the PlaNS laboratory.

International Conferences on Research and Applications of Plasmas, PLASMA-2017

The International Conferences on Research and Applications of Plasmas (PLASMA) have been organized every two years since 1993. The scope of the PLASMA conference series, which idea was originally to facilitate the exchange of knowledge and to spread the collaboration between the scientists and engineers from the Eastern European Countries, covers most of issues of broadly understood plasma physics and technology.PLASMA-2017, organized by the Institute of Plasma Physics and Laser Microfusion (IPPLM), took place from 18th September to the 22nd September 2017 at the Central Agriculture Library in Warsaw, Poland. The conference covered scientific areas like:I. Elementary processes and general plasma physicsII. Plasmas in tokamaks and stellarators (MCF)III. Plasmas generated by laser beams and Inertial Confinement Fusion (ICF)IV. Plasma produced by Z-pinch and Plasma-Focus dischargesV. Low-temperature and dusty plasmaVI. Space plasmas and laboratory astrophysics

Thermal stability of the krypton Hall effect thruster

Abstract The Krypton Large IMpulse Thruster (KLIMT) ESA/PECS project, which has been implemented in the Institute of Plasma Physics and Laser Microfusion (IPPLM) and now is approaching its final phase, was aimed at incremental development of a ~500 W class Hall effect thruster (HET). Xenon, predominantly used as a propellant in the state-of-the-art HETs, is extremely expensive. Krypton has been considered as a cheaper alternative since more than fifteen years; however, to the best knowledge of the authors, there has not been a HET model especially designed for this noble gas. To address this issue, KLIMT has been geared towards operation primarily with krypton. During the project, three subsequent prototype versions of the thruster were designed, manufactured and tested, aimed at gradual improvement of each next exemplar. In the current paper, the heat loads in new engine have been discussed. It has been shown that thermal equilibrium of the thruster is gained within the safety limits of the materials used. Extensive testing with both gases was performed to compare KLIMT’s thermal behaviour when supplied with krypton and xenon propellants.

Comparison of silicon drift detectors made by Amptek and PNDetectors in application to the PHA system for W7-X

Abstract The paper presents comparison of two silicon drift detectors (SDD), one made by Amptek, USA, and the second one by PNDetector, Germany, which are considered for a soft X-ray diagnostic system for W7-X. The sensitive area of the first one is 7 mm2 × 450 μm and the second one is 10 mm2 × 450 μm. The first detector is cooled by a double-stage Peltier element, while the second detector is cooled by single-stage Peltier element. Each one is equipped with a field-effect transistor (FET). In the detector from Amptek, the FET is mounted separately, while in the detector from PNDetector, the FET is integrated on the chip. The nominal energy resolution given by the producers of the first and the second one is 136 eV@5.9 keV (at -50°C) and 132 eV@5.9 keV (at -20°C), respectively. Owing to many advantages, the investigated detectors are good candidates for soft X-ray measurements in magnetic confinement devices. They are suitable for soft X-ray diagnostics, like the pulse height analysis (PHA) system for the stellarator Wendelstein 7-X, which has been developed and manufactured at the Institute of Plasma Physics and Laser Microfusion (IPPLM), Warsaw, in collaboration with the Max Planck Institute for Plasma Physics (IPP), Greifswald. The diagnostic is important for the measurements of plasma electron temperature, impurities content, and possible suprathermal tails in the spectra. In order to choose the best type of detector, analysis of technical parameters and laboratory tests were done. Detailed studies show that the most suitable detector for the PHA diagnostics is the PNDetector.

Advanced laboratory for testing plasma thrusters and Hall thruster measurement campaign

Abstract Plasma engines are used for space propulsion as an alternative to chemical thrusters. Due to the high exhaust velocity of the propellant, they are more efficient for long-distance interplanetary space missions than their conventional counterparts. An advanced laboratory of plasma space propulsion (PlaNS) at the Institute of Plasma Physics and Laser Microfusion (IPPLM) specializes in designing and testing various electric propulsion devices. Inside of a special vacuum chamber with three performance pumps, an environment similar to the one that prevails in space is created. An innovative Micro Pulsed Plasma Thruster (LμPPT) with liquid propellant was built at the laboratory. Now it is used to test the second prototype of Hall effect thruster (HET) operating on krypton propellant. Meantime, an improved prototype of krypton Hall thruster is constructed.

Fusion related research with laser-induced-breakdown-spectroscopy on metallic samples at the ENEA-Frascati laboratory.

The study of plasma-wall interactions is of paramount importance for continuous and fault free operations in thermonuclear fusion research to monitor the damages of plasma facing components (PFCs), plasma pollution from impurities and wall retention of hydrogen isotopes, like tritium. These needs make laser-induced-breakdown-spectroscopy (LIBS) a suitable candidate for a real time monitoring of PFCs in the current and next generation fusion devices, like ITER. It is also worthwhile for the quantitative analysis of surfaces, with micro-destructivity of the sample and depth profiling capabilities with sub-micrometric sensitivity. In this paper LIBS spectroscopy is exploited as a valid diagnostic tool for PFCs at the ENEA Research Center in Frascati (Italy) and at the Institute of Plasma Physics and Laser Microfusion (IPPLM) of Warsaw (Poland). The activities have been focused on LIBS characterization of samples simulating PFCs surfaces eroded/redeposited or contaminated from nuclear fuel after or during the normal operation of the reactor.

High Power Laser Laboratory at the Institute of Plasma Physics and Laser Microfusion: equipment and preliminary research

Abstract The purpose of this paper is to present the newly-opened High Power Laser Laboratory (HPLL) at the Institute of Plasma Physics and Laser Microfusion (IPPLM). This article describes the laser, the main laboratory accessories and the diagnostic instruments. We also present preliminary results of the first experiment on ion and X-ray generation from laser-produced plasma that has been already performed at the HPLL.

Numerical investigation of the Krypton Large IMpulse Thruster

Although xenon has long remained the propellant of choice for Hall effect and ion thrusters, its very high price has motivated the investigation of other noble gases as cost-effective options. The development of a 500 W-class Hall thruster at the Institute of Plasma Physics and Laser Microfusion (IPPLM) aims at demonstrating the possibility of operating with krypton at efficiencies close to that obtained with xenon. However, krypton's lower ionization cross-sections need to be compensated by a significant increase of the mass flow rate in comparison with xenon. The subsequent increase of the thermal load has a large impact on the thermal design of the thruster. In order to assess the operating parameters and the thermal fluxes expected during krypton operation, an extensive parametric study of Krypton Large Impulse Thruster's performance was conducted with the one-dimensional time-dependent hydrodynamic HETMAn solver developed at IPPLM. Comparative computations for xenon and krypton confirm that high efficiencies with krypton are possible, with a predicted maximum efficiency only a few per cent below that of xenon, although at mass flow rates ∼50% higher.

Comparison of Biophysical and Radiological Responses of Bio-Test Objects to Pulsed and Continuous X-Ray and Neutron Irradiations

Aims: To correlate qualitatively and quantitatively biological effectiveness of irradiations of bio-test objects by neutrons, Xand gamma-rays within a wide range of doses, dose rates (dose powers), durations of action and spectral contents of the radiations. Study Design: These irradiations were done with the help of well-known and newly elaborated sources of the above radiations based on isotopes, fission reactors, X-ray tubes and Dense Plasma Focus (DPF) devices. Place and Duration of Study: Institute of Metallurgy and Material Science (IMET), Institute of Plasma Physics and Laser Microfusion (IPPLM), Moscow State University (MSU), and Medical Radiological Research Center (MRRC), between June 2007 and December 2011. Research Article International Research Journal of Pure & Applied Chemistry, 3(1): 32-47, 2013 33 Methodology: As biological test objects of different contents and complexity we used enzymes of various types, serum, seminal fluid, human lymphocytes. Enzymes activity prior to and after irradiation was measured using spectrophotometer (Hitachi) within the wavelength range Δ = 300÷750 nm according to up-to-date techniques. In the comparative researches the cytogenetic action of fission neutrons (generated by nuclear reactors) and of fusion 14-MeV neutrons (from DPF) were studied with the most widespread test-system – chromosomal aberrations in human lymphocytes. Results: The range of the variations of the coefficient of biological effectiveness for neutron radiation of dissimilar dose rates (dose powers) and neutron spectra as a rule does not go out from the limits of physiological oscillations at the neutron dose power that changes within 9 orders of magnitude (till the figure 10 Gy/min) and it coincides with the “classic” dose rate effect (a quadratic part of dose curves for cell survival or chromosomal aberrations). Yet in the field of radioenzymology the very powerful X-ray radiation results in activation or suppression of enzymes at doses differing by 4-5 orders of magnitude (to lesser doses) compared with analogous effects obtained with low power isotope and Xray tube sources. Conclusion: Resemblance of neutron action on dose powers within 9 orders of magnitude gives hope of applicability of the DPF neutron generators for the potential methods of neutron therapy instead of dangerous, expensive and cumbersome nuclear reactors. But the anomalously strong X-ray influence upon enzymes dictates careful application of super-high power X-ray pulses and demands further investigations of the nature of these effects.

Method of ions acceleration for laser-induced implantation of semiconductor materials

The application of electrostatic fields for the formation of laser-generated ions makes it possible to control the ion stream parameters in broad energy and current density ranges. It also permits to remove the useless ions from the ion stream designed for laser-induced implantation and deposition of layers of semiconductor materials. For acceleration of ions a special electrostatic system has been completed and tested at the Institute of Plasma Physics and Laser Microfusion (IPPLM). A repetitive Nd: glass laser with energy of ∼0.5 J in a 3.5 ns pulse, wavelength of 1.06 μm, repetition rate of up to 10 Hz and intensity on the target of up to 1011 W cm−2, has been recently employed to produce ions emitted from irradiated solid targets. The movable target holder was located inside the cylindrical box connected with a high-voltage source (up to 50 kV). The ions passing through the diaphragm in this box were accelerated in the system of electrodes in the electrostatic field formed in the gap between the box and a grid mounted at the end of the grounded cylindrical electrode. The parameters of the ion streams were measured with the use of several ion collectors and an electrostatic ion energy analyzer (IEA). The Ge ion stream attained energy of up to 30 keV and ion fluency 1011 ions/cm2 for one laser shot. The maximum ion charge state measured with the use of IEA was 3+.

Laser-produced plasmas interaction with high pulsed magnetic field

This work presents results of two experiments accomplished at the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw: (1) investigations of the influence of magnetic field on a laser-produced plasma in the presence or absence of the background plasma, (2) investigations of dynamics of laser-produced plasma in a strong magnetic field. The aim of experiment 1 (performed in collaboration with the Institute of Laser Physics (ILP) RAS, Novosibirsk, Russia) was laboratory simulation of depolarization and deflection of plasma streams drifting across magnetic field in geoplasma background. An Nd:glass laser (5 ns, 2 J) was used to produce the plasma inside Helmholtz coils . The diagnostics for studying the interaction processes were: ion collectors, Langmuir and magnetic probes and an image converter camera. We present a comparison of the effects investigated in that experiment with some phenomena occurring in the geoplasma. In experiment 2 the plasma was produced by means of a Nd:glass laser (1 ns, 10 J) focused on a solid target located in a single-turn coil . Plasma expansion was investigated with an automated interferometer along the magnetic field lines and perpendicular to these lines. From the interferograms, it has been revealed that the plasma stream has a clear asymmetry for caused by an unmagnetized ion Rayleigh-Taylor instability.

Optimized four-channel Nd: glass laser system for compression experiments

This paper presents the design of the four-channel Nd: glass high power laser system in the Kaliski Institute of Plasma Physics and Laser Microfusion (IPPLM) in its optimized version, based on a theoretical analysis of propagation of radiation in the real laser channel.