Examinando por Autor "Jain, Jalaj"

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    Experimental measurements of high-energy photons in X-rays pulses emitted from a hundred joules plasma focus device and its interpretations
    (Elsevier B.V., 2020-03) Jain, Jalaj; Moreno, Jose; Davis, Sergio; Boraa, Biswajit; Paveza, Cristian; Avaria, Gonzalo; Soto, Leopoldo
    In the present work, efforts are made to identify the presence of high energy photons in X-rays pulses, emitted from a hundred joules plasma focus device, PF-400J. Two different experiments were carried out, with the insertion of a lead piece inside the hollow anode of PF-400J and without insertion of the lead piece. A pair of two photomultiplier tubes (PMTs) was mounted in the axial direction and a similar pair of PMTs was mounted in the radial direction, simultaneously. After establishing a correlation between two PMTs in each pair, one of the PMTs in both directions was blocked by a rectangular slab of the lead of thickness ~17 mm. Linear attenuation coefficient (LAC) of lead was estimated using the PMTs signals. Later, the X-rays energies were interpolated for the estimated LAC values in both cases, with and without insertion of lead piece inside the hollow anode. Interpolated energies reveal the presence of 0.55–0.85 MeV photons in the X-rays pulses in the axial direction, while, in radial direction ranges 0.4–0.9 MeV, for the case without lead inserted inside the hollow anode. Insertion of the lead inside the hollow anode does not change the X-rays energies significantly, nonetheless, it increases X-rays repetition rate per hundred discharges. The presence of high energy photons in the X-rays pulses indicates the existence of relativistic electrons. To explain it, induced electric and magnetic fields were estimated using generalized Ohm’s law. We conclude that the electron acceleration mechanisms might not be the same in the axial and radial directions.
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    Ítem
    Kappa distribution from particle correlations in nonequilibrium, steady-state plasmas
    (American Physical Society, 2023-12) Davis, Sergio; Avaria, Gonzalo; Bora, Biswajit; Jain, Jalaj; Moreno, José; Pavez, Cristian; Soto, Leopoldo
    Kappa-distributed velocities in plasmas are common in a wide variety of settings, from low-density to high-density plasmas. To date, they have been found mainly in space plasmas, but are recently being considered also in the modeling of laboratory plasmas. Despite being routinely employed, the origin of the kappa distribution remains, to this day, unclear. For instance, deviations from the Maxwell-Boltzmann distribution are sometimes regarded as a signature of the nonadditivity of the thermodynamic entropy, although there are alternative frameworks such as superstatistics where such an assumption is not needed. In this work we recover the kappa distribution for particle velocities from the formalism of nonequilibrium steady-states, assuming only a single requirement on the dependence between the kinetic energy of a test particle and that of its immediate environment. Our results go beyond the standard derivation based on superstatistics, as we do not require any assumption about the existence of temperature or its statistical distribution, instead obtaining them from the requirement on kinetic energies. All of this suggests that this family of distributions may be more common than usually assumed, widening its domain of application in particular to the description of plasmas from fusion experiments. Furthermore, we show that a description of kappa-distributed plasma is simpler in terms of features of the superstatistical inverse temperature distribution rather than the traditional parameters κ and the thermal velocity vth.