共查询到20条相似文献,搜索用时 578 毫秒
1.
A. E. Shikanov E. D. Vovchenko K. I. Kozlovskii V. I. Rashchikov V. L. Shatokhin 《Technical Physics》2018,63(4):511-518
A model for acceleration of deuterons and generation of neutrons in a compact laser-plasma diode with electron isolation using magnetic field generated by a hollow cylindrical permanent magnet is presented. Experimental and computer-simulated neutron yields are compared for the diode structure under study. An accelerating neutron tube with a relatively high neutron generation efficiency can be constructed using suppression of electron conduction with the aid of a magnet placed in the vacuum volume. 相似文献
2.
Ryzhkov V. A. Pyatkov I. N. Kibler E. V. Zhuravlev M. V. Remnev G. E. 《Russian Physics Journal》2021,64(1):151-155
Russian Physics Journal - Collective acceleration of protons and deuterons is compared in the same geometry of a Luce diode with a polyethylene anode at an accelerating diode voltage of 250 kV,... 相似文献
3.
S. A. Barengol’ts G. A. Mesyats É. A. Perel’shtein 《Journal of Experimental and Theoretical Physics》2000,91(6):1176-1182
An ecton mechanism for the operation of the cathode spot and the concept of a deep nonstationary potential well are used as the basis to propose a model of collective ion acceleration at the spark stage of a vacuum discharge. It is shown that in principle a deep potential well can form in the presence of an external electric field and the conditions for its formation in an explosive-emission diode are clarified. The proposed model can explain the main processes leading to collective ion acceleration and shows good agreement with the experimental results. 相似文献
4.
A. E. Shikanov K. I. Kozlovskiy E. D. Vovchenko A. A. Isaev 《Physics of Atomic Nuclei》2017,80(11):1673-1676
A diagnostic procedure establishing a relation between the energy of a laser pulse W (0.1 ≤ W ≤ 0.8) and the number of deuterons N d extracted from the laser plasma in a vacuum accelerating diode with magnetic isolation of electrons is presented. The diagnostics is based on the measurement of neutrons generated at a target, which is a part of the ion collector at the same time. The results of experimental research and numerical modeling for the accelerating voltage at a diode interval up to 400 kV are presented. 相似文献
5.
Ter-Avetisyan S Schnürer M Nickles PV Kalashnikov M Risse E Sokollik T Sandner W Andreev A Tikhonchuk V 《Physical review letters》2006,96(14):145006
We report on the generation and laser acceleration of bunches of energetic deuterons with a small energy spread at about 2 MeV. This quasimonoenergetic peak within the ion energy spectrum was observed when heavy-water microdroplets were irradiated with ultrashort laser pulses of about 40 fs duration and high (10(-8)) temporal contrast, at an intensity of 10(19) W/cm(2). The results can be explained by a simple physical model related to spatial separation of two ion species within a finite-volume target. The production of quasimonoenergetic ions is a long-standing goal in laser-particle acceleration; it could have diverse applications such as in medicine or in the development of future compact ion accelerators. 相似文献
6.
A laptop neutron source suited for the most demanding field or laboratory applications is presented. It is based on laser ablation of CD2 primary targets, plasma acceleration of the D+ ions, and their irradiation of secondary CD2 targets. The deuterium–deuterium (D-D) fusion reaction is induced in the secondary target, according to the values of fusion cross-section versus deuteron energy, which show a significant probability also at relatively low ion energies. The experiments were completed in the PALS laboratory, Prague, detecting monoenergetic neutrons at 2.45 MeV with an emission flux of about 109 neutrons per laser shot. Other experiments demonstrating the possibility to induce D-D events were performed at IPPLM, Warsaw, and at INFN-LNS, Catania, where the deuterons were accelerated at about 4 MeV and 50 keV, respectively. In the last case, a low laser intensity and a post-ion acceleration system were employed. A special interaction chamber, under vacuum, is proposed to develop a new source of monochromatic neutrons or thermalized distribution of neutrons 相似文献
7.
E. D. Vovchenko K. I. Kozlovskij A. E. Shikanov A. R. Karimov A. A. Isaev A. A. Plekhanov O. V. Deryabochkin 《Physics of Atomic Nuclei》2019,82(10):1424-1428
The collective acceleration of laser plasma ions in a magnetic field generated by a powerful fast-growing current pulse in a low-inductive conical spiral is studied. The velocity of ions for a number of elements which significantly differ in atomic weight are obtained on the basis of collector measurements. The maximum velocity of both light (lithium) and heavy (lead) ions exceed the value of 108 cm/s; for ions of lead, the corresponding energy amounts to a value of ∼1 MeV. A mathematical model of ion acceleration is proposed and simulation results are compared with the experiment. 相似文献
8.
The generation of a 250-μs-wide electron beam in a plasma-emitter diode is studied experimentally. A plasma was produced by a pulsed arc discharge in hydrogen. The electron beam is extracted from a circular emission hole 3.8 mm in diameter under open plasma boundary conditions. The beam accelerated in the diode gap enters into a drift space in the absence of an external magnetic field through a hole 4.1 mm in diameter made in the anode. The influence of electron current deposition at the edge of the anode hole on the beam’s maximum attainable current, above which the diode gap breaks down, is studied for different accelerating voltages and diode gaps. The role of processes occurring on the surface of the electrodes is shown. For an accelerating voltage of 32 kV, a mean emission current density of 130 A/cm2 is achieved. The respective mean strength of the electric field in the acceleration gap is 140 kV/cm. Using the POISSON-2 software package, the numerical simulation of the diode performance is carried out and the shape of steady plasma emission boundaries in the cathode and anode holes is calculated. The influence of the density of the ion current from the anode plasma surface on the maximum attainable current of the electron beam is demonstrated. 相似文献
9.
The results of a study of the generation of a gigawatt-level pulsed ion beam formed by a diode with an explosive-emission
potential electrode in self-magnetic insulation mode are presented. The experiments have been performed on the TEMP-4M ion
accelerator operating in double-pulse formation mode: the first pulse is negative polarity (300–500 ns, 100–150 kV) and the
second is positive (150 ns, 250–300 kV). The ion current density is 20–40 A/cm2; the beam consists of protons and carbon ions. To increase the efficiency of the ion current generation, a circular geometry
diode is proposed. It is shown that with the new design, the plasma is effectively formed over the entire working surface
of the graphite potential electrode. During ion beam generation, magnetic insulation of the electrons is achieved over the
entire length of the diode (B/B
cr ≥ 3). Because of the high drift velocity, the transit time of electrons in the anode-cathode gap is 3–5 ns, whilst the transit
time of C+ carbon ions exceeds 8 ns. This indicates low efficiency self-magnetic insulation for this geometry of diode. At the same
time, it has been observed experimentally that during ion current generation (the second pulse), the electron component of
the total current is suppressed by a factor of 4–5. A new mechanism of limiting the electron emission, which explains the
decrease in the electron component of the total current in the circular diode with self-magnetic insulation, is proposed. 相似文献
10.
A fiber Bragg grating (FBG) acceleration sensor interrogated by a DFB laser diode is demonstrated; the sensor is fabricated by packaging a FBG on to a cantilever; the interrogation scheme takes advantage of the intensity modulation of the narrow spectral bandwidth light of a distributed feedback laser diode, when the reflection spectrum curve of a FBG moves due to the strain which is applied on the sensor. The sensor’s response to the frequency and acceleration is measured by the experiment, and the factors which have an impact on the sensor’s sensitivity are also discussed. 相似文献
11.
A physical model is proposed for macroparticle acceleration in an expanding laser plasma. Two acceleration mechanisms are considered, based on absolutely inelastic interaction of the laser-plasma ions with the macroparticle surface: acceleration due to the ion momentum and reactive acceleration due to evaporation of the surface layer. The processes are mathematically described with the aid of the gasdynamics equations with thermal conductivity. Approximate analytic expressions are obtained and permit an estimate of the laser-plasma energy as well as of the quasiparticle momentum as functions of the parameters of the laser pulse, of the target, and of the macroparticle. The analytic solutions are compared with numerical computations using the RAPID program; the comparison confirms that the results agree qualitatively and quantitatively.Quantum Radiophysics Division, Lebedev Physics Institute. Translated from Preprint No. 209 of the Lebedev Physics Institute, Academy of Sciences USSR, Moscow, 1990. 相似文献
12.
A model of forming deuteron fluxes and neutron generation in an axial plasma diode with two external anodes and a transparent
internal hollow cathode is suggested. Such configuration provides longitudinal deuteron oscillations (inertial confinement)
and required frequency of collisions with slow deuterons in the cathode plasma. On the basis of the suggested model of neutron
generation, the neutron flux generated in the course of D(d, n)3
He nuclear reactions is approximately calculated. The examined diode system seems to be promising for the development of compact
controllable neutron sources with increased operation lifetime and transverse size no more than 5 cm. 相似文献
13.
K. Quinn P. A. Wilson B. Ramakrishna G. Sarri L. Romagnani A. Pipahl O. Willi L. Lancia J. Fuchs D. C. Carroll M. N. Quinn P. Gallegos X. H. Yuan P. McKenna R. J. Clarke D. Neely M. Notley A. Macchi M. Borghesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):293-297
New method of neutron spectrum recovery described in the paper involves accelerated deuterons (that produce neutrons in DD
reaction) and allows getting neutron spectrum in any direction from computed time-velocity characteristics of deuterons. Time of flight signals registered in various distances and directions are used, that makes
information involved in the recovery process (Monte-Carlo simulation) more complete than in a one-directional case, although
additional assumption about axial symmetry of deuterons motion, is required. In the paper recent results of two standard tests
of the proposed method are presented demonstrating its capability to recover neutron spectrum from time-of-flight signals. 相似文献
14.
15.
Yu. B. Gurov L. Yu. Korotkova S. V. Lapushkin R. V. Pritula V. G. Sandukovsky V. A. Chernyshev 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(4):370-374
Experimental results on the spectra and yields of deuterons forming in the absorption reaction of stopped π? mesons by nuclei are presented. The A-dependences of deuteron yields are found. Contributions from various processes to the formation of deuterons are evaluated in the context of a proposed phenomenological model. 相似文献
16.
This paper deals with computer simulation of plasma erosion opening switch (PEOS) operation in the context of short-pulse high-power ion beam (HPIB) generation in microsecond store systems. The scaling of PEOS parameters and ion diode characteristics with various operating conditions was determined. The simulations showed the best PEOS characteristics for a hydrogen plasma (i.e., the lowest mass) with a high flow velocity and low density, although for some applications a plasma with A/Z > 1 may be preferable. It was shown that the efficiency of HPIB generation in the diode depends on its location relative to the PEOS, the time delay of anode plasma formation, the use of a spiral electrode in the PEOS region, and the use of an arrangement involving an ion return current bypass through the PEOS region. The optimization of the PEOS and ion diode with coaxial configurations and 100 kJ stored in the 600-kV Marx yielded a 16-percent overall efficiency HPIB generation in the diode, with a diode voltage and power of 4.2 MV and 0.42 TW, respectively. 相似文献
17.
K. I. Kozlovsky A. S. Martynenko E. D. Vovchenko M. I. Lisovsky A. A. Isaev 《Physics of Atomic Nuclei》2017,80(11):1677-1682
The results of examination of the insulating magnetic field in an accelerating ion diode are presented. This field is produced in order to suppress the electron current and thus enhance the neutron yield of the D(d, n)3He nuclear reaction. The following two designs are discussed: a gas-filled diode with inertial electrostatic confinement of ions and a vacuum diode with a laser-plasma ion source and pulsed magnetic insulation. Although the insulating field of permanent magnets is highly nonuniform, it made it possible to extend the range of accelerating voltages to U = 200 kV and raise the neutron yield to Q = 107 in the first design. The nonuniform field structure is less prominent in the device with pulsed magnetic insulation, which demonstrated efficient deuteron acceleration with currents up to 1 kA at U = 400 kV. The predicted neutron yield is as high as 109 neutrons/pulse. 相似文献
18.
A model of the unstable stage of a spark discharge in vacuum is proposed, which describes all typical manifestations of this
stage, including current spikes in the diode, an increase in the potential at the cathode flame front, collective acceleration
of ions in vacuum and plasma diodes, change in the cathode erosion mechanism, and the emergence of electron microbeams with
a high current density at the anode. It is shown that these processes are associated with the formation of a charged electron
layer of a spatially inhomogeneous plasma at the cathode flame boundary at the unstable stage of the spark discharge in vacuum.
The emergence of this layer is associated with a limited emissive ability of the plasma at the cathode flame front during
its expansion in vacuum. This leads to disruption of the plasma (field-induced emission of electron from the boundary region
of the flame) and the formation of a short-lived charged plasma, viz., high-density ion cluster at the cathode flame boundary.
The estimates obtained using this model are in good agreement with the experimental data on physical processes at the unstable
stage of a vacuum spark discharge. 相似文献
19.
As part of the effort to develop an electrohydrodynamically (EHD) driven lithium ion source for the Particle Beam Fusion Accelerator II (PBFA II) at Sandia National Laboratories, we have begun experiments with liquid lithium and liquid lithium nitrate-filled anodes on the PI-110A accelerator. Several methods have been used to provide a lithium or lithium-bearing vertical anode surface that can be maintained above its melting point. Here we report preliminary results which indicate that a high purity (> 80 percent) Li+ beam is achievable from these anodes. Diagnostics include measurements of diode voltage, diode current, ion current, and a Thomson parabola analyzer to measure ion species. The possibility that ions are produced by an EHD phenomenon is discussed. Other mechanisms of ion production are considered. 相似文献