Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Plasma waves excited by intense laser beams can be harnessed to produce femtosecond duration bunches of electrons with relativistic energies. The very large electrostatic forces of plasma density wakes trailing behind an intense laser pulse provide field potentials capable of accelerating charged particles to high energies over very short distances, as high as 1 GeV in a few millimetres. The short length scale of plasma waves provides a means of developing very compact high-energy accelerators, which could form the basis of compact next-generation light sources with unique properties. Tuneable X-ray radiation and particle pulses with durations of the order of or less than 5 fs should be possible and would be useful for probing matter on unprecedented time and spatial scales. If developed to fruition this revolutionary technology could reduce the size and cost of light sources by three orders of magnitude and, therefore, provide powerful new tools to a large scientific community. We will discuss how a laser-driven plasma wakefield accelerator can be used to produce radiation with unique characteristics over a very large spectral range.

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Electron bunch lengthening due to space-charge forces in state-of-the-art rf photoinjectors limits the minimum bunch length attainable to several hundreds of femtoseconds. Although this can be alleviated by increasing the transverse dimension of the electron bunch, a larger initial radius causes path-length differences in both the rf cavity and in downstream focusing elements. In this paper we show that a curved cathode virtually eliminates these undesired effects. Detailed numerical simulations confirm that significantly shorter bunches are produced by an rf photogun with a curved cathode compared to a flat cathode device. The proposed novel method will be used to provide 100 fs duration electron bunches for injection into a laser-driven plasma wakefield accelerator.

The article proposes a solution of a problem of polarization error compensation for radar object direction finding by means of conical scan method. The solution is considered at signal processing level that makes possible to avoid polarization limitations in antennas engineering. The purpose of the article is to substantiate a model for polarization-induced errors by conical scan direction finding method and to develop an algorithmic technique for the considered method correction with regard to arbitrary polarization conditions of radar interaction. The results are presented by analytical model along with quantitative estimates of polarization-induced errors of direction finding and the computational procedure of the error compensation as well as by analysis of imperfectness factors for the proposed procedure exposing its practical applicability.

For the last few years in INRP RFNC-VNIIEF the works on development of a multi-module «Gamma» facility have been conducted. An important part of each module is a pulse transmission system (PTS), providing transportation of a high-volt electromagnetic pulse (~2.3 MV, ~60 ns) to a diode load, positioned at an angle of ~80° to the axis of a module's forming system. Basic PTS units: a water-insulated transmission line (WTL), having a bended section, a vacuum insulator stack and a magnetically-insulated transmission line (MITL). At the first stage an experimental sample of PTS with diameter 0.65 m was studied. Performed studies allowed a conclusion that the given experimental PTS sample did not possess enough electric strength, what was a reason for electric breakdowns in the bended section of WTL. Reasons for breakdown occurrence were analyzed; conclusions were made on the necessity for increasing PTS diameter. As a result a PTS version with diameter ~1 m was developed. This paper presents results of the experimental studies as a part of the facility module. Totally 200 shots of the module were performed with given PTS at different charge voltage of its forming lines. Reliable and steady operation of all PTS units, as well as correspondence between output module parameters and their calculated values were proved. When using PTS, without MITL in the module diode load, with impedance ~3 Ohm the pulses with power 1.5 TW and total electron energy in a pulse ~80 kJ were obtained. When using PTS with cylindrical MITL of 1.6 m length, the pulse power was ~1.4 TW.