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Project of submillimeter free electron laser (FEL) is developed at BINP in collaboration with IAP [1] . The FEL scheme is based on a high current electron beam (E e = 5−20 MeV, I b = 1−2 kA, τ= 160−200 ns) generated at the new linear induction accelerator (LIA) [2] , [3] . According to our theoretical analysis, such beam allows us to generate coherent pulses of submm-radiation in the frequency range 0.3-1 THz. The radiation power in such scheme can reach a sub-megawatt level and the energy content up to ~100 J.

A new method for SQL query implementation in a parallel execution environment Apache Spark in a package mode was developed on the basis of Bloom Filter Cascade Application (BFCA). It includes representation of the original query in a form of a few subqueries and intermediate tables, where the Bloom filters are created and applied. Then the representation is transformed into Scala code. Theoretical justification of the developed method is provided. The theoretical estimation of the network data transmission volume reduction (shuffle) is shown on an example. The efficiency of the method is demonstrated on the example of Q3 (three tables join) and Q17 (correlated subquery) queries from the TPC-H test. The developed BFCA method is more than 2 times faster and more than 10 times better on shuffle volume (as compared to Spark SQL) on Q3 at a Scale Factor SF=500. The BFCA is 8 times faster on Q17 than Hive (Spark SQL cannot implement Q17).

This article reviews record versions processing (reconciliation). It provides an algorithm for NoSQL database record versions management. It develops a record versions reconciliation model that is simultaneously updated by multiple users. The model estimates record versions reconciliation time and the number of versions simultaneously stored in a database. Based on the modeling results a designer can provide recommendations on the maximum number of users (or applications) simultaneously working with one document (database record). This is important in case there are limitations imposed on the document reconciliation time. It describes preparation and execution of experiments in a cloud, for model adequacy analysis.

This article considers NoSQL database replication problems. It analyzes the influence of the N, W, R replication parameters on the consistency characteristics of database record replicas (N -- the total number of one record's replicas, W -- number of replicas for write operation execution into a database, R -- number of replicas for record read operation execution from a database). It describes a developed model for eventual consistency (W+R=N), obtaining probability estimate that during the process of N-W replica updates there will be at least one read request out of non-updated replicas. It also proposes a model for strong consistency of the replicas in NoSQL databases, which allows for estimation of random wait time of the read request for the record update completion. It describes the process for preparation and execution of experiments in the cloud for model calibration and its validation.

Analysis of the existing techniques for approximate query processing of Big Data, based on sampling, histograms and wavelets, demonstrates that wavelet-based methods can be effectively utilized for OLAP purposes due to their advantages in terms of handling multidimensional data and querying single cells as well as aggregate values from a data warehouse. At the same time the current wavelet-based methods for approximate query processing have certain deficiencies making difficult to implement them in practice. In particular, most of the techniques struggle with arbitrarily size data either imposing a restriction on a dimension length to be a multiple of a power of two, or complicating decomposition algorithms what leads to the construction time increase and difficulties with error estimations. Also, there is a lack of methods for approximate processing based on wavelets with a bounded error and a confidence interval for both single and aggregate values. Our contribution in this paper is introduction of a new wavelet method for approximate query processing which handles arbitrarily sized multidimensional datasets with minor extra calculations and provides a bounded error of the single or aggregate value reconstruction. It is demonstrated that the new method allows evaluating a confidence interval of the query error depending on a given compression ratio of a data warehouse or performing an inverse task, i.e. evaluating the required data warehouse compression ratio for a given allowable error. The introduced method was applied and verified over real epidemiological datasets to support research in finding correlations and patterns in disease spread and clinical signs correlations. It was demonstrated that the accuracy of the estimated error is acceptable for retrieving single and aggregate value, query time processing advantage depends on compression ratio and volume of the processed data.

A source of epithermal neutrons based on a tandem accelerator with vacuum insulation and a lithium neutron producing target was proposed and created to develop boron neutron capture therapy of malignant tumors. A laboratory was created in 2014 to be prepared for practical implementation of the therapy using the accelerator neutron source. To achieve this goal it is necessary to increase the current and the energy of the proton beam, to create a new neutron producing target, neutron beam shaping assembly and so on. The article provides a description of the created source of epithermal neutrons, presents and discusses the results of experiments and declares future plans.

Electromagnetic emission from plasma in the vicinity of the fundamental plasma frequency and at its double value during a relativistic electron beam (REB) relaxation is studied at the GOL-3 facility [1]. In our paper we will present results of experiments carried out on the specialized GOL-PET device for the emission of terahertz radiation from plasma at its density ∼ 1015 cm−3 and the magnetic field strength 2–4 T. The plasma column created by a high-voltage discharge in the GOL-PET device has its diameter 6 cm and the length about of 250 cm. The injected electron beam has the following parameters: ∼0.8 MeV, ∼20 kA, ∼10 μs. The beam current density in the plasma is up to 3kA/cm2. The radiation in the frequency interval from 0.1 up to 0.8 THz is analyzed by fast eight-channel polychromator and polarimeter based on frequency selection quasioptical elements.

Summary form only given. Fast plasma heating in a multi-mirror magnetic trap by a high-current beam of relativistic electrons is a promising way to achieve fusion-grade plasma parameters. A high-level Langmuir turbulence develops during the beam-plasma interaction. These high-energy-density plasma oscillations can generate electromagnetic (EM) radiation in a wide frequency range extending from the plasma frequency to its 2nd harmonic. Thus the spectrum of EM emission can achieve 1 THz at 3·1015 cm−3 plasma density. The first experiments on the generation of sub-mm waves by a beam-heated plasma carried out at the GOL-3 facility were presented in [1]. Here we present results on sub-mm wave generation for plasma densities 1014–1015 cm−3 during injection of a relativistic electron beam (≤ 0.8 MeV, 30 kA, ∼10 ms).

One of possible ways to generate submillimeter wave and THz radiation is to use transformation of plasma waves into electromagnetic radiation at strong Langmuir turbulence [1]. We had already described some implementation of such method at the GOL-3 experiments [2–4], wherein the mechanism of plasma heating was recognized as the excitation of strong Langmuir turbulence (LT) via a two-stream instability induced by the propagating high current beam. The detailed theoretical consideration of LT-induced electromagnetic emission from turbulent plasmas distinguishes two main processes responsible for electromagnetic radiation emission during the beam-plasma interaction at GOL-3. First, plasmon scattering on plasma density fluctuations yields electromagnetic emission at the plasma frequency ω p (“ω p -process”). Second, plasmon-plasmon merging results in production of photons in the vicinity of the double plasma frequency 2ω p (“2ω p -process”). For plasma densities of 1014–1015 cm−3, corresponding output radiation frequencies are located in the range from mm to sub-mm waves, ω P /2π ≌ 90–283 GHz, 2ω P /2π ≌ 180–566 GHz.

Paper presents results of investigations of electromagnetic radiation emission in a submillimeter range at strong Langmuir turbulence pumped by a relativistic electron beam. Radiation at double plasma frequency is generated due to plasmon-plasmon merging. Results of radiation power measurements are compared with theoretical estimations.

Study of Langmuir turbulence (LT) in plasma and LT-induced nonlinear phenomena remains an important topic of the fundamental plasma science. A distinctive LT's feature is possibility of electromagnetic radiation emission on plasma frequency (ν p ) and dual plasma frequency (2ν p ) due to processes of plasmon conversion on plasma density fluctuations and plasmon-plasmon merging respectively. Well-identified in solar radio-flares, these processes remained weakly studied in laboratory plasmas.

Essential progress was achieved in experiments on heating the dense plasma in the multimirror trap GOL-3 by high power relativistic electron beam in last few years. The beam parameters at the experiments were the following: electron energy ∼1 MeV, beam current ∼25 kA, beam current density in plasma ∼2 kA/cm2, pulse duration about 10 ms, total energy of the beam pulse ∼150 kJ [1]. Due to the high level of the current density and effect of a novel mechanism of ion heating the temperature of ions reached 2−3 keV at the electron temperature about 3 keV for the plasma density ∼1015 cm−3 [1]. Energy confinement time of the plasma in these experiments has reached the level of 1 ms. The basic condition of such parameters achievement is anomalously low electron thermal conductivity along the trap axis which is provided by small scale Longmuir turbulence developing as a result of two-stream instability [2]. In order to analyze a prospect of further increase of plasma parameters for reaching a fusion area, to elongate the beam pulse duration was decided. As the first step on solving this task we are performing the experiments at the accelerator U-2 on 1.5 fold increase of the E-beam duration. To investigate in more details the process beam-plasma interaction we carry out measurements on temporal dynamics of the plasma electron distribution function in the range of 0–5 keV and on evolution of energy distribution functions of the beam electrons as well. We also measure an electromagnetic radiation gone out from the plasma column as result of transformation of two Langmuir waves in electromagnetic one in strong turbulent plasma. This electromagnetic radiation is measured in the frequency band 210−550 GHz. Results of the pointed experiments and their discussion are presented in this paper.

Essential progress was achieved in experiments on heating the dense plasma in the multimirror trap GOL-3 by high-power relativistic electron beam in last few years. The beam parameters at the experiments were the following: electron energy ~1 MeV, beam current ~25 kA, beam current density in plasma ~2 kA/cm2, pulse duration 9 mus, total energy of the beam pulse ~150 kJ. Due to the high level of the current density and effect of a novel mechanism of ion heating the temperature of ions reached 2-3 keV at the electron temperature about 3 keV for the plasma density ~1015 cm-3. Energy confinement time of the plasma in these experiments has reached the level of 1 ms. The mechanism of fast ion heating is based on the collective ion acceleration along the magnetic field lines produced by high-gradients of the electron pressure in the plasma due to enhanced heating in the mirrors. The basic condition for such mechanism realization is anomalously low electron thermal conductivity along the trap axis which is provided by small scale Langmuir turbulence developing as result of two-stream instability. In order to analyze fusion prospects of such way of plasma heating in the long solenoid trap it is necessary to investigate experimentally the possibility of further increase of plasma parameters by the elongation of the beam pulse. As the first step on solving this task we have performed the experiments at the accelerator U-2 on 1.5 fold increase of the e-beam duration. Results of these experiments are presented in this paper. Conditions for durable generation in magnetically insulated diode, stable transportation and compression in the magnetic field of intense REB found in the experiments, permit us to increase the beam pulse duration from 9 mus to 14 mus with somewhat less energy of the electrons but with the same level of the energy content in the pulse. In the paper we describe the experiments on the diode voltage shaping for better matching of pulse generator with the accelerator diode as well as the results of measurements of the beam cross section by means of X-ray obscure and sectional calorimeter. Also we discuss the directions of future investigations aimed to the increase of the beam parameters in order to obtain (5-10) keV temperature of the plasma confined in multimirror trap.

Summary form only given. Essential progress has been achieved on GOL-3 experimental facility (Novosibirsk) in recent years. Deuterium plasma with density 1015 cm-3 is heated by relativistic electron beam up to temperatures in order of 2 keV, both for electron and ion plasma components. Neutron output has been obtained for the plasma. The paper presents one possible way to increase neutron output. It can be done if small condensed matter target with density about 1 containing deuterium would be placed into the plasma. Estimations of neutron output for different targets are presented in the paper, obtained by means of numerical simulation. The basis of the calculation model is physico-mathematical model of hot plasma interaction with solid target. Equations of gas dynamics, kinetics of level population of multi-charged ions and radiation transfer in lines and continuum, kinetics of chemical decomposition of target matter or its evaporation are solved self-consistently. Calculations of neutron output for targets of frozen deuterium, lithium deuteride and deuteration polyethylene have been done. Estimation of tritium accumulation in reaction Li3 6 + n0 1 = H1 3 + He2 4 for lithium deuteride target is presented. Neutron output has been calculated for targets with deuterium-tritium mixture as well. Size of target with maximum neutron output has been obtained

Collective interactions of a microsecond electron beam with a plasma and its fast heating is being investigated at the GOL-3-II facility. This activity is mainly directed for production of a hot dense (10/sup 15/-10/sup 17/ cm/sup -3/) plasma in long open trap in order to study the multimirror and "wall" confinement of such a plasma. The plasma that is already obtained and can in principle be obtained in this facility is of interest for a broad spectrum of applications, like controlled fusion, a pulsed neutron source, X-ray flash lamps, UV laser etc. Recent results performed at the GOL-3-II facility are presented. These are beam energy losses, plasma heating and electron and ion temperature measurements.

Summary form only given, as follows. Varying the pulse duration and amplitude of a pressure wave in solids can provide a unique possibility to control solid-state transformations and composition of new products. Realization of such a control by varying temperature pulses is already well known. As to the influence of the pressure variation, the importance of the duration of pressure pulses was claimed in a number of publications in the field of mechanochemistry, but real experiments are hard to come by. The aim of our work is to find a way for the control of the time profile of the pressure wave in solids by using a high-power microsecond REB for surface irradiation of a solid target. Generally speaking, high-power particle beams with short pulse duration are widely used as one of methods to generate high pressure pulses in solids, for example, for nuclear fusion application. Our presentation deals with the results of experimental and theoretical studies of application of microsecond REB to induce solid-state transformations under special conditions. Several typical examples belonging to different classes of pressure-induced solid-state transformations are considered, including structural transformations with and without significant contribution of an electronic component, with model systems ranging from simple inorganic salts and oxides to complex oxides and organic molecular solids. The evolution of pressure inside a solid target induced by the irradiation of its surface by microsecond REB with variable current density (equal to the one generated by U-2 accelerator) is simulated. The results of the simulations are used to optimize the geometry and the material of the target comprising the sample, in which a solid-state transformation is to be induced. The experimental diagnostics is discussed, which can be used to measure the conditions of the experiment (in particular, pressure dynamics), to follow the transformation and to characterize its product.