Calculation of fusion rates at extremely low energies in laser plasmas

2010 ◽  
Vol 6 (S274) ◽  
pp. 44-47 ◽  
Author(s):  
D. Mascali ◽  
N. Gambino ◽  
S. Tudisco ◽  
A. Anzalone ◽  
A. Bonanno ◽  
...  
Keyword(s):  
Nuclear Reactions ◽  
Fusion Reaction ◽  
Reaction Rates ◽  
Debye Screening ◽  
Fusion Reactions ◽  
Plasma Dynamics ◽  
Laser Plasmas ◽  
Low Energies ◽  
Screening Factor ◽  
The One

AbstractAt temperatures and densities that are typical of plasmas produced by lasers pulses interacting with solid targets, at power intensities I > 1012W/cm2, the classical Debye screening factor in nuclear reactions becomes comparable with the one of the solar core. Preliminary calculations about the total number of fusion reactions have been performed following an hydrodynamical approach for the description of the plasma dynamics. This approach is propaedeutic for future measurements of D-D fusion reaction rates.

scholarly journals An increase in the 12C+12C fusion rate from resonances at astrophysical energies

2019 ◽  
Vol 52 (382) ◽  
pp. MISC6-MISC8
Author(s):  
Aurora Tumino
Keyword(s):  
Neutron Stars ◽  
Cross Sections ◽  
Coulomb Barrier ◽  
Reaction Rate ◽  
Nuclear Reactions ◽  
Massive Stars ◽  
Reaction Rates ◽  
Fusion Reactions ◽  
Trojan Horse Method ◽  
Carbon Burning

Carbon burning powers pivotal scenarios that influence the fate of stars, such as the late evolutionary stages of massive stars (exceeding eight solar masses), superbursts from accreting neutron stars and progenitors of Type Ia supernovae. It proceeds through the 12C+12C fusion reactions that produce an \( \alpha \) particle and neon-20 or a proton and sodium-23 —that is, 12C(12C, \( \alpha \) )20Ne and 12C(12C, \( p \))23Na— at temperatures greater than \( 0.4 \cdot 10^9 \) K, corresponding to astrophysical energies exceeding a megaelectronvolt (MeV), at which such nuclear reactions are more likely to occur in stars. The cross-sections for those carbon fusion reactions (probabilities that are required to calculate the rate of the reactions) have never been measured below 2 MeV because of exponential suppression arising from the Coulomb barrier (the Coulomb barrier is around 6 MeV). The reference rate at temperatures below \( 1.2\cdot 10^9 \) K relies on extrapolations that ignore the effects of possible low-lying resonances. In Tumino et al. (2018), we report the measurement of the 12C(12C, \( \alpha_{0,1} \)) 20Ne and 12C(12C, \( p_{0,1} \)) 23Na reaction rates (where the subscripts 0 and 1 stand for the ground and first excited states of 20Ne and 23Na, respectively) at centre-of-mass energies from 2.7 to 0.8 MeV using the Trojan Horse method and the deuteron in 14N. This is an indirect technique aiming at measuring low-energy nuclear reactions unhindered by the Coulomb barrier and free of electron screening. The deduced cross-sections exhibit several resonances that are responsible for a very large increase of the reaction rate at the relevant temperatures. In particular, around \( 5\cdot 10^8 \) K, the reaction rate is more than 25 times larger than the reference value. This finding may have significant implications such as lowering the temperatures and densities required for the ignition of carbon burning in massive stars and decreasing the superburst ignition depth in accreting neutron stars in the direction to reconcile observations with theoretical models.

scholarly journals New scheme to produce aneutronic fusion reactions by laser-accelerated ions

2015 ◽  
Vol 33 (1) ◽  
pp. 117-122 ◽  
Author(s):  
C. Baccou ◽  
S. Depierreux ◽  
V. Yahia ◽  
C. Neuville ◽  
C. Goyon ◽  
...  
Keyword(s):  
Energy Production ◽  
Nuclear Reactions ◽  
Fusion Reaction ◽  
Fusion Energy ◽  
Fusion Reactions ◽  
Aneutronic Fusion ◽  
Single Target ◽  
First Results ◽  
Fusion Products ◽  
Accelerated Particles

AbstractThe development of high-intensity lasers has opened the field of nuclear reactions initiated by laser-accelerated particles. One possible application is the production of aneutronic fusion reactions for clean fusion energy production. We propose an innovative scheme based on the use of two targets and present the first results obtained with the ELFIE facility (at the LULI Laboratory) for the proton–boron-11 (p–11B) fusion reaction. A proton beam, accelerated by the Target Normal Sheat Acceleration mechanism using a short laser pulse (12 J, 350 fs, 1.056 µm, 1019 W cm−2), is sent onto a boron target to initiate fusion reactions. The number of reactions is measured with particle diagnostics such as CR39 track-detectors, active nuclear diagnostic, Thomson Parabola, magnetic spectrometer, and time-of-flight detectors that collect the fusion products: the α-particles. Our experiment shows promising results for this scheme. In the present paper, we discuss its principle and advantages compared with another scheme that uses a single target and heating mechanisms directly with photons to initiate the same p–11B fusion reaction.

Chromatographic Analysis of Elastomeric Polyurethanes

1987 ◽  
Vol 60 (3) ◽  
pp. 555-577 ◽  
Author(s):  
P. A. D. T. Vimalasiri ◽  
R. P. Burford ◽  
J. K. Haken
Keyword(s):  
Chemical Structure ◽  
Fusion Reaction ◽  
Reaction Rates ◽  
Liquid Extraction ◽  
Fusion Reactions ◽  
Coating Films ◽  
Condensation Products ◽  
Liquid Liquid Extraction ◽  
Fusion Methods ◽  
Adhesive Coating

Abstract Both alkali and acid fusion reactions can be used to cleave polyurethane polymers successfully. Fusion reaction rates are much faster than conventional aqueous alkali or acid fusion methods. Separation of fragments could be carried out using the liquid-liquid extraction procedures described. After quantitative and qualitative analysis of fragments using GC, SEC, and HPLC, chemical structure of the polymer can be established. Although the work described uses only elastomeric polyurethanes for the development of the analytical schemes, these schemes can be used to analyze other types of polyurethanes such as “Spandex” fibers, adhesive coating films, and plastics. The procedures described have also been used for the analysis of polyamide resins which are condensation products.

scholarly journals Underground Nuclear Astrophysics: pushing direct measurements toward the Gamow window

2020 ◽  
Vol 227 ◽  
pp. 01015
Author(s):  
Paolo Prati
Keyword(s):  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Cosmic Ray ◽  
Reaction Rates ◽  
Carbon Ions ◽  
Ongoing Research ◽  
Ion Accelerator ◽  
Direct Measurements ◽  
Low Energies ◽  
Deep Underground

The aim of experimental nuclear astrophysics is to provide information on the nuclear processes involved in astrophysical scenarios at the relevant energy range. However, the measurement of the cross section of nuclear reactions at low energies present formidable difficulties due to the very low reaction rates often overwhelmed by the background. Several approaches have been proposed and exploited to overcome such severe obstacles: in such frame, the idea to install a low energy - high intensity ion accelerator deep underground, to gain high luminosity while reducing the cosmic ray background, brought more than 25 years ago, to the pilot LUNA experiment. LUNA stands for Laboratory for Underground Nuclear Astrophysics: in the cave under the Gran Sasso mountain (in Italy) first a 50 kV and then a 400 kV single-ended accelerator for protons and alphas were deployed and produced plenty of data mainly on reactions of the H-burning phase in stars. Recently, similar facilities have been installed and/or proposed in other underground laboratories in US and China. LUNA as well is going to make a big step forward, with a new machine in the MV range which will be able to provide intense beams of protons, alphas and carbon ions. The rationale of underground nuclear astrophysics will be presented together with the last updates on the ongoing research programs.

scholarly journals 16O(p,α)13N makes explosive oxygen burning sensitive to the metallicity of the progenitors of type Ia supernovae

2019 ◽  
Vol 627 ◽  
pp. A146
Author(s):  
E. Bravo
Keyword(s):  
Supernova Remnants ◽  
Fusion Reaction ◽  
Reaction Rates ◽  
Type Ia Supernovae ◽  
Fusion Reactions ◽  
Maximum Brightness ◽  
Theoretical Predictions ◽  
Type Ia ◽  
Standard Values ◽  
Ia Supernovae

Even though the main nucleosynthetic products of type Ia supernovae belong to the iron-group, intermediate-mass alpha-nuclei (silicon, sulfur, argon, and calcium) stand out in their spectra up to several weeks past maximum brightness. Recent measurements of the abundances of calcium, argon, and sulfur in type Ia supernova remnants have been interpreted in terms of metallicity-dependent oxygen burning, in accordance with previous theoretical predictions. It is known that α-rich oxygen burning results from 16O→12C followed by efficient 12C+12C fusion reaction, as compared to oxygen consumption by 16O fusion reactions, but the precise mechanism of dependence on the progenitor metallicity has remained unidentified so far. I show that the chain 16O(p,α)13N(γ,p)12C boosts α-rich oxygen burning when the proton abundance is large, increasing the synthesis of argon and calcium with respect to sulfur and silicon. For high-metallicity progenitors, the presence of free neutrons leads to a drop in the proton abundance and the above chain is not efficient. Although the rate of 16O(p,α)13N can be found in astrophysical reaction rate libraries, its uncertainty is unconstrained. Assuming that all reaction rates other than 16O(p,α)13N retain their standard values, an increase by a factor of approximately seven of the 16O(p,α)13N rate at temperatures in the order 3−5 × 109 K is enough to explain the whole range of calcium-to-sulfur mass ratios measured in Milky Way and LMC supernova remnants. These same measurements provide a lower limit to the 16O(p,α)13N rate in the mentioned temperature range, on the order of a factor of 0.5 with respect to the rate reported in widely used literature tabulations.

scholarly journals Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

2021 ◽  
Vol 1 ◽  
pp. 67
Author(s):  
Silvano Tosti
Keyword(s):  
Thermodynamic Analysis ◽  
Reaction Rate ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Fusion Reaction ◽  
Operating Conditions ◽  
Fusion Reactions ◽  
Simplified Approach ◽  
Nuclear Fusion Reactions ◽  
Classical Thermodynamics

Background: So far the feasibility of nuclear reactions has been studied only through the evaluation of the reaction rate, which gives us information about the kinetics, while the thermodynamic analysis has been limited to evaluations of the change in enthalpy without any consideration of the change in entropy. Methods: This work examines the thermodynamics of nuclear fusion reactions through a simplified approach. The analysis introduces the thermodynamic study of fission and fusion reactions through their comparison with a chemical process. Results: The main result is that fission reactions are always spontaneous (ΔG < 0) since a lot of energy is released in the form of heat and the system moves spontaneously towards a more disordered state. In contrast, fusion reactions are spontaneous only when the enthalpic contribution of the change in Gibbs energy overcomes the entropic contribution. This condition is verified when the temperature of the process is below a characteristic value T*, calculated as the ratio between the energy corresponding to the mass defect and the change of entropy of the fusion reaction. Conclusions: Due to the unavailability of data related to entropy changes in fusion reactions, only a qualitative thermodynamic analysis has been carried out. Through such analysis, the influence of the operating conditions over the spontaneity of fusion processes has been discussed. The final considerations emphasize the role of the thermodynamics analysis that should be implemented in the current studies that, so far, have been mainly based on the assessment of the reaction rate and exothermicity of fusion reactions.

scholarly journals New parametrization for the 3He(d, p) 4He fusion reaction rate and refinement of the Lawson criterion for d-3He thermonuclear reactors

2021 ◽  
Vol 2103 (1) ◽  
pp. 012197
Author(s):  
I B Alper ◽  
A I Godes ◽  
V L Shablov
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Cross Section ◽  
Reaction Rate ◽  
Nuclear Reactions ◽  
Fusion Reaction ◽  
Theoretical Method ◽  
Reaction Rates ◽  
Lawson Criterion ◽  
Astrophysical Factor

Abstract We present a new parametrization of the d + 3He → p + 4He fusion reaction astrophysical factor based on the effective range approximation, which is an effective theoretical method for describing near-threshold, including resonance, nuclear reactions. In the framework of this approximation we describe experimental data on the energy dependence of the cross section and the astrophysical factor within the experimental uncertainties in the energy range of 0-800 keV. On this basis we calculate the temperature dependence of the Maxwellian-averaged reaction rate in the range of 0-400 keV. In conclusion, we discuss the effect of the calculated reaction rates on the Lawson criterion for thermonuclear reactors based on d-3He fuel.

scholarly journals Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

2021 ◽  
Vol 1 ◽  
pp. 67
Author(s):  
Silvano Tosti
Keyword(s):  
Thermodynamic Analysis ◽  
Reaction Rate ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Fusion Reaction ◽  
Operating Conditions ◽  
Fusion Reactions ◽  
Simplified Approach ◽  
Nuclear Fusion Reactions ◽  
Classical Thermodynamics

Background: So far the feasibility of nuclear reactions has been studied only through the evaluation of the reaction rate, which gives us information about the kinetics, while the thermodynamic analysis has been limited to evaluations of the change in enthalpy without any consideration of the change in entropy. Methods: This work examines the thermodynamics of nuclear fusion reactions through a simplified approach. The analysis introduces the thermodynamic study of fission and fusion reactions through their comparison with a chemical process. Results: The main result is that fission reactions are always spontaneous (ΔG < 0) since a lot of energy is released in the form of heat and the system moves spontaneously towards a more disordered state. In contrast, fusion reactions are spontaneous only when the enthalpic contribution of the change in Gibbs free energy overcomes the entropic contribution. This condition is verified when the temperature of the process is below a characteristic value T*, calculated as the ratio between the energy corresponding to the mass defect and the change of entropy of the fusion reaction. Conclusions: Due to the unavailability of data related to entropy changes in fusion reactions, only a qualitative thermodynamic analysis has been carried out. Through such analysis, the influence of the operating conditions over the spontaneity of fusion processes has been discussed. The final considerations emphasize the role of the thermodynamics analysis that should be implemented in the current studies that, so far, have been mainly based on the assessment of the reaction rate and exothermicity of fusion reactions.

Search for Enhanced D+D+D Reactions under D+ Beam Irradiation into TiDx Targets

2005 ◽  
Vol 107 ◽  
pp. 55-58
Author(s):  
A. Takahashi ◽  
H. Miyamaru ◽  
K. Ochiai
Keyword(s):  
Charged Particle ◽  
Nuclear Reactions ◽  
Fusion Reaction ◽  
Cascade Reactions ◽  
Beam Irradiation ◽  
Fusion Reactions ◽  
Particle Spectra ◽  
Reaction Channels ◽  
Counter Telescope ◽  
Three Body

To search possible enhancement of three-body D+D+D fusion reaction in condensed matter, we have studied for 10 years about emitted charged particle spectra from titanium-deuterate (TiDx) samples under low energy D+ beam irradiation. By gas loading technique with changing temperature, we prepared TiDx samples with x = 1.4 - 1.8. A TiDx sample was mounted in a vacuum chamber with cooling and irradiated with 70 – 300 keV D+ beam. A delta-E and E type counter telescope using two Si-SSD detectors was used for charged particle spectroscopy. Charged particles from D+D fusion reactions, e.g., 3MeV protons and 1MeV tritons were observed in every case, as usually expected. Sometimes, in addition, we observed “unknown” peaks at about 4.8MeV, which were identified to be two kinds of particles, i.e., helium and triton. We could not find any candidate reaction channels in two-body nuclear reactions of D+ beam and possible target nuclei (H, D, T, He-3, Li-6, Li-7, Be-9, C-12, N-14, N-15, Ti, etc.) including impurity reactions. We concluded that the 4.8MeV particles were from the D+D+D fusion to the out-going reaction channel of He-3 (4.75MeV) + T(4.75MeV). The yield ratios of [3D]/[2D] were obtained as a function of D+ beam energy in the range of 50 to 300 keV, revealed the increasing trend in the lower energy range than 100 keV and were on the order of 1E-4 which was anomalously large compared with the estimated values on the order of 1E- 30 based on the conventional random nuclear process for the cascade reactions of three-body interaction, i.e, D+D to He-4* and He-4* + D reactions.

scholarly journals Spontaneity of nuclear fusion: a qualitative analysis via classical thermodynamics

2021 ◽  
Vol 1 ◽  
pp. 67
Author(s):  
Silvano Tosti
Keyword(s):  
Thermodynamic Analysis ◽  
Reaction Rate ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Fusion Reaction ◽  
Operating Conditions ◽  
Fusion Reactions ◽  
Simplified Approach ◽  
Nuclear Fusion Reactions ◽  
Classical Thermodynamics

Background: So far the feasibility of nuclear reactions has been studied only through the evaluation of the reaction rate, which gives us information about the kinetics, while the thermodynamic analysis has been limited to evaluations of the change in enthalpy without any consideration of the change in entropy. Methods: This work examines the thermodynamics of nuclear fusion reactions through a simplified approach. The analysis introduces the thermodynamic study of fission and fusion reactions through their comparison with a chemical process. Results: The main result is that fission reactions are always spontaneous (ΔG < 0) since a lot of energy is released in the form of heat and the system moves spontaneously towards a more disordered state. In contrast, fusion reactions are spontaneous only when the enthalpic contribution of the change in Gibbs free energy overcomes the entropic contribution. This condition is verified when the temperature of the process is below a characteristic value T*, calculated as the ratio between the energy corresponding to the mass defect and the change of entropy of the fusion reaction. Conclusions: Due to the unavailability of data related to entropy changes in fusion reactions, only a qualitative thermodynamic analysis has been carried out. Through such analysis, the influence of the operating conditions over the spontaneity of fusion processes has been discussed. The final considerations emphasize the role of the thermodynamics analysis that should be implemented in the current studies that, so far, have been mainly based on the assessment of the reaction rate and exothermicity of fusion reactions.

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