Deuteron Energy Distribution Research Articles

Simulation of neutron emission spectra from neutral beam-heated plasmas in the EAST tokamak

The neutron emission spectrum from neutral beam-heated plasmas of the Experimental Advanced Superconducting Tokamak (EAST) is investigated based on first-principles simulations of the fast deuteron energy distribution. Parametrized plasma profiles are used to determine the beam deposition and fast deuteron distribution function using the NUBEAM code. The deuteron distribution is also interpreted with the help of empirical models and the components in the neutron energy spectrum are computed for different viewing lines using a Monte Carlo method. The resulting observational possibilities are discussed for the case of a time-of-flight neutron emission spectrometer optimized for EAST.

High-resolution gamma ray spectroscopy measurements of the fast ion energy distribution in JET 4He plasmas

High-resolution γ-ray measurements were carried out on the Joint European Torus (JET) in an experiment aimed at accelerating 4He ions in the MeV range by coupling third harmonic radio frequency heating to an injected 4He beam. For the first time, Doppler broadening of γ-ray peaks from the 12C(d, pγ)13C and 9Be(α, nγ)12C reactions was observed and interpreted with dedicated Monte Carlo codes based on the detailed nuclear physics of the processes. Information on the confined 4He and deuteron energy distribution was inferred, and confined 4He ions with energies as high as 6 MeV were assessed. A signature of MHD activity in γ-ray traces was also detected. The reported results have a bearing on diagnostics for fast ions in the MeV range in next step fusion devices.

Measurements of fast deuterons from plasma accelerator by means of PM-355 track detectors

This paper reports on studies of fast ions (mostly deuterons) emitted from an RPI (Rod-Plasma-Injector) plasma accelerator. The first aim was the verification of applicability of PM-355 track detectors for dosimetry of lower-energy (<200 KeV) deuterons. The second aim was information about energy spectra of deuterons from RPI-IBIS device in different operational modes. Mass- and energy spectra of ions were investigated with a Thomson-analyzer and PM-355 detectors. On the recorded deuteron-parabolas we chose points, and from numbers of tracks we determined the deuteron energy distribution. In the slow-mode the energy distribution peak was observed at about 40 keV, while the maximum energy amounted to about 150 keV. Those measurements confirmed an influence of the initial gas-conditions on energy distributions of the deuteron streams. The results are of importance for plasma-physics and applications. Another result was the confirmation that PM-355 detectors might be used for accurate measurements of low-energy (<200 keV) deuterons.

Determination of Deuteron Energy Distribution From Neutron Diagnostics in a Plasma-Focus Device

Fast neutrons from deuteron-deuteron fusion reactions were used for a study of fast deuterons in the PF-1000 plasma-focus device. The energy spectrum of neutrons was determined by the time-of-flight method using ten scintillation detectors positioned downstream, upstream, and side-on the experimental facility. Neutron energy-distribution functions enabled the determination of axial and radial components of energy of deuterons producing the fusion neutrons, as well as a rough evaluation of the total energy distribution of all fast deuterons in the pinch. It was found that the total deuteron energy-distribution function decreases with the deuteron energy more slowly than the tail of the Maxwellian distribution for 1-2-keV deuterons.

Coulomb expansion of deuterated methane clusters irradiated by an ultrashort intense laser pulse

The simulations of three-dimensional particle dynamics show that when irradiated by an ultrashort intense laser pulse, the deuterated methane cluster expands and the majority of deuterons overrun the more slowly expanding carbon ions, resulting in the creation of two separated subclusters. The enhanced deuteron kinetic energy and a narrow peak around the energy maximum in the deuteron energy distribution make a considerable contribution to the efficiency of nuclear fusion compared with the case of homonuclear deuterium clusters. With the intense laser irradiation, the nuclear fusion yield increases with the increase of the cluster size, so that deuterated heteronuclear clusters with larger sizes are required to achieve a greater neutron yield.

Measurement of the astrophysical S factor for dd interaction at ultralow deuteron-collision energies using the inverse Z pinch

This paper is devoted to measurement of the astrophysical S factor and cross sections of the d + d → 3He + n reaction at ultralow deuteron-collision energies. Formation of the flow of the accelerated deuterons incident on the CD2 solid-state target was made within the scheme of the inverse Z pinch. The liner in the initial state was a hollow supersonic deuterium jet of radius of 15 mm and length of 20 mm. The experiment was carried out at the pulsed high-current accelerator (I=950 kA, τ=80 ns) of the Institute of High-Current Electronics (Tomsk, Russia). Measurement of the deuteron energy distribution was performed through an analysis of the time distributions of the intensity of the liner radiation (Hα and Hβ lines) generated during the liner radial movement from the axis. Recording of this radiation was carried out by optical detectors placed along the direction of the liner moving from its axis. The measured value of the astrophysical S factor for the dd reaction at the average deuteron collision energy E coll=3.69 keV was equal to S(E coll=3.69 keV)=58.2±18.1 keV b. The dd-reaction cross section calculated using the found value of the S factor and known representation of the reaction cross section as the product of the barrier factor and the astrophysical S factor was σ dd n (E coll=3.69 keV)=(1.33±0.41)×10−30 cm2.

Deuterium liner and multiparametric studies of the formation of an inverse Z-pinch

A method and results of measurements are presented of the ion energy distribution in a deuterium liner accelerated in the inverse Z-pinch, in which the plasma is accelerated electrodynamically from the liner axis. Knowledge of the deuteron energy distribution is of primary importance for the correct interpretation of the experimental results from the study of the dd-reaction in the range of infralow energies with the use of a liner plasma. Experiments were carried out in a high-current pulsed accelerator (I=950 kA, τ=80 ns) at the Institute of High-Current Electronics of the Siberian Division of the Russian Academy of Sciences (Tomsk, Russia). In the initial state, the liner is a supersonic hollow deuterium jet 32 mm in diameter and 20 mm in length. The liner parameters were measured with the help of optical detectors of H α and H β deuterium lines and magnetic probes arranged in a radial direction (along the direction the liner expansion). In addition, scintillation spectrometers and BF3 counters were used to measure the intensity of the neutron flux produced in the d + d → 3He + n reaction. The results obtained by simultaneously analyzing the data from magnetic probes, optical detectors, and neutron detectors point to the possibility of using a rather simple method for measuring the parameters of the liner accelerated up to energies of 3–6 keV.

Nonperturbing meaurement of energy distribution function of confined D-T fusion alpha particles in Joint European Torus plasmas using impurity induced neutralization (abstract)

We present measurements of the energy distribution function of fusion α particles in the range 0.8⩽E(MeV)⩽3 in hot-ion H-mode plasmas, using a NPA. Two contributions to the measured atomic flux are distinguished: (i) alpha particles due to direct neutralization effected in double charge–exchange reactions with intrinsic plasma impurities C4+, Be2+, and He0, and (ii) MeV energy deuterons formed by elastic scattering on fusion alpha particles, their neutralization effected by reactions with C5+, Be3+, He1+, and D0. Application of the impurity induced neutralization model to the measurements is presented. Deduced fusion α particle and knock-on deuteron energy distribution functions are compared with Fokker–Planck simulations in which measured time-dependent α-particle source and collisionality are used.

Neutron-proton radiative capture at 14.4 MeV

The energy spectrum of deuterons from the H(n, d)γ reaction at 14.4 MeV was measured with a counter telescope. The c.m. differential cross section of this reaction was deduced from the deuteron energy distribution. A least-squares fit yielded a total cross section of σ = 30.6±1.8 μb, which is about 10% larger than the theoretical prediction. The isotropy ratio a b was found to be 0.08±0.06 and the asymmetry parameter was determined to be d b = 0.12±0.09 .

Photoproduction of Deuterons from Carbon at Several Hundred MeV

The yield curve of deuterons of 45 MeV produced at 57° from carbon exposed to the bremsstrahlung of the maximum energy between 400 MeV and 720 MeV and the energy distributions of deuterons by the brems-strahlung of 650 MeV and 720 MeV were measured. The excitation function of deuterons of 45 MeV and the energy distribution of deuterons at the photon energy of 685 MeV were reduced from the data by the method of photon difference. The identification of deuterons was made by the time-of-flight method with an analyzing magnet. The measurement was analyzed in terms of the independent pair model. The results show that the cross section of the (γ, d ) reaction is consistent with the independent pair model with the mesonic process.