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Pushing the limits of existing plasma focus towards 1016 fusion neutrons with Q=0.01

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plasma Science and Technology 2022年第11期24卷 47-53页

作者： Sing LEE Institute for plasma focus Studies 32 Oakpark DriveChadstone VIC3148Australia Physics Department University of MalayaKuala Lumpur 50603Malaysia INTI International University Nilai 71800Malaysia Fuse Energy Technologies Napierville QC J0J 1L0Canada

Existing conventional megajoule plasma focus machines with 2–3 MA are producing fusion neutron yields of several times 10^(11) in deuterium operation,the fusion yields predominantly being the beam-gas target.Increasing the current to 10 MA and using 50%–50%D-T mixture will scale the neutron yield towards 10^(16) D-T fusion neutrons.In this work,we derive the Lawson criterion for plasma focus devices with a beam-target fusion neutron mechanism,so that we may glimpse what future technological advancements are needed for a break-even Q=1 plasma focus.We perform numerical experiments with a present-day feasible 0.9 MV,8.1 MJ,11 MA machine operating in 100 Torr in 50%–50%D-T mixture.The Lee Code simulation gives a detailed description of the plasma focus dynamics through each phase,and provides plasma and yield parameters which show that out of 1.1×10^(19) fast beam ions produced in the plasma focus pinch,only 1.24×10^(14) ions take part in beam-target fusion reactions within the pinch,producing the same number of D-T neutrons.The remnant beam ions,numbering at least 10^(19),exit the focus pinch at 1.9 MeV,which is far above the 115 keV ion energy necessary for an optimum beam-target cross-section.We propose to regain the lost fusion rates by using a high-pressure D-T-filled drift-tube to attenuate the energy of the remnant beam ions until they reach the energy for the optimum fusion cross-section.Such a fusion enhancement tube would further harvest beam-target fusion reactions by increasing the interaction path length(1 m)at increased interaction density(6 atm).A gain factor of 300 is conservatively estimated,with a final yield of 3.7×10^(16) D-T neutrons carrying kinetic energy of 83.6 kJ,demonstrating Q=0.01.

关键词： plasma focus simulation neutron enhancement fusion harvester plasma focus

Reliable Field Distortion Spark Gap for plasma focus

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plasma Science and Technology 2007年第4期9卷 504-507页

作者： S.HUSSAIN M.ZAKAULLAH Department of Physics University of Sargodha40100 SargodhaPakistan Department of Physics Quaid-i-Azam University45320 IslamabadPakistan

A simple, low cost, easily maintained, and reliable field distortion spark gap has been developed to operate at a voltage up to 30 kV. The header construction necessary to attach the spark gap switch to a single 12.5 μF, 40 kV （10 k J） capacitor is described. The main features of the spark gap are its wide range of voltage operation, high current capacity, low inductance and long lifetime. The performance of spark gap has been tested in a plasma focus and results are presented in this report.

关键词： field distortion spark gap plasma focus

Low Energy plasma focus as an Intense X-ray Source for Radiography

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plasma Science and Technology 2004年第3期6卷 2296-2300页

作者： S.Hussain M.Zakaullah Shujaat Ali A.Waheed Department of Physics Quaid-i-Azam University 45320 Islamabad PakistanDepartment of Physics Quaid-i-Azam University 45320 Islamabad PakistanDepartment of Physics Quaid-i-Azam University 45320 Islamabad PakistanPINSTECH P. O. Box 2151 44000 Islamabad Pakistan

Study on X-ray emission from a low energy (1.8 kJ) plasma focus devicepowered by a 9 μF capacitor bank, charged at 20 kV and giving peak discharge current of about 175kA by using a lead-inserted copper-tapered anode is reported. The X-ray yield in different energywindows is measured as a function of hydrogen filling pressure. The maximum yield in 4π-geometry isfound to be (27.3+-1.1) J and corresponding wall plug efficiency for X-ray generation is 1.52+-0.06%. X-ray emission, presumably due to bombarding activity of electrons in current sheath at theanode tip was dominant, which is confirmed by the pinhole images. The feasibility of the device asan intense X-ray source for radiography is demonstrated.

关键词： plasma focus X-ray source radiography

Magnetic field induction and magnetic force distribution profiles in plasma focus discharge device

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plasma Science and Technology 2021年第7期23卷 110-120页

作者： A A LASHIN T M ALLAM H A EL-SAYED Kamal M AHMED S A WARD H M SOLIMANand M A ABOUELATTA plasma and Nuclear Fusion Department Nuclear Research CentreEgyptian Atomic Energy AuthorityInshas 13759Egypt Faculty of Engineering Delta University for Science and TechnologyGamasa 11152Egypt Electrical Engineering Department Faculty of Engineering at ShoubraBenha UniversityCairo 11629Egypt

We report a simple-to-perform technique to investigate the distribution of the azimuthal magnetic field induction,Bθ,and the induced magnetic force acting on the plasma current sheath(PCS)in a plasma focus(PF)discharge.This in situ measurement technique can undoubtedly be beneficial when other fast-imaging techniques are not available.techniques are not available.Experimental work was conducted in the low-energy Mather-type EAEA-PF1 device operated in argon.The axial distribution(Bθ)z along the coaxial electrodes system was measured with a four magnetic-probe set technique at different radial distances(r=2.625×10^(−2) to 4.125×10^(−2) m)within the annular space between the coaxial electrodes during the 1st and 2nd half cycles of the discharge current waveform,where inner electrode of coaxial electrode system has a+ve polarity and−ve polarity,respectively.Axial,radial and total magnetic force distribution profiles were estimated from Bθdata.Investigation of PCS shape in terms of its inclination(curvature)angle,θ,along the axial rundown phase and the correlation between the magnetic forces per unit volume acting on the PCS,the inclination angleθof the PCS,and the formation of a powerful PF action during the 1st and 2nd half cycles is carried out.Dependence of inclination angle,θ,on total magnetic force per unit volume acting on PCS axial motion was studied,separately,during the 1st and 2nd half cycles.

关键词： plasma focus azimuthal magnetic field magnetic force inclination angle plasma current sheath

Electron Temperature Measurement Using PIN Diodes as Detectors to Record the X-ray Pulses from a Low-Energy Mather-Type plasma focus

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plasma Science and Technology 2004年第2期6卷 2199-2203页

作者： M.Asif Amna Ikram Institute of plasma Physics Chinese Academy of SciencesUniversity of Engineering and Technology Lahore 54000 Pakistan Hefei 230031 China Department of Physics Government College University Lahore 54000 Pakistan

In the experiment to determine the plasma electron temperature, a modifiedmultichannel PIN diodes assembly is used as detectors to record the X-ray pulses from a low-energyMather-type plasma focus device energized by a 32μF, 15 kV (3.6kJ) single capacitor, with deuteriumas a filling gas. The ratio of the integrated bremsstrahlung emission transmitting through foils tothe total incident flux as a function of foil thickness at various temperatures is obtained forfoil absorbers of material. Using 3 μm, 6 μm, 9 μm,12 μm,15 μm and 18 μm thick aluminiumabsorbers, the transmitted X-ray flux is detected. By comparing the experimental and theoreticalcurves through a computer program, the plasma electron temperature is determined. Results show thatthe deuterium focus plasma electron temperature is about 800 eV.

关键词： plasma focus PIN diodes X-ray foil absorber thickness

Development of a radiographic method for measuring the discrete spectrum of the electron beam from a plasma focus device

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plasma Science and Technology 2017年第7期19卷 26-33页

作者： Neda SHAMSIAN Babak SHIRANI BIDABADI Hosein PIRJAMADI Department of Nuclear Engineering Faculty of Advanced Sciences and Technologies University of Isfahan

An indirect method is proposed for measuring the relative energy spectrum of the pulsed electron beam of a plasma focus device. The Bremsstrahlung x-ray, generated by the collision of electrons against the anode surface, was measured behind lead filters with various thicknesses using a radiographic film system. A matrix equation was considered in order to explain the relation between the x-ray dose and the spectral amplitudes of the electron beam. The electron spectrum of the device was measured at 0.6 mbar argon and 22 kV charging voltage, in four discrete energy intervals extending up to 500 keV. The results of the experiments show that most of the electrons are emitted in the 125-375 keV energy range and the spectral amplitude becomes negligible beyond 375 keV.

关键词： magnetized plasma plasma focus plasma diagnostics electron beam energyspectrum x-ray dosimetry

Synthesis of TiN/a-Si_3N_4 thin film by using a Mather type dense plasma focus system

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Chinese Physics B 2013年第5期22卷 381-385页

作者： T. Hussain R. Ahmad N. Khalid Z. A. Umar A. Hussnain Center For Advanced Studies in Physics (CASP) 1-Church RoadGC University Department of Physics Government College University

A 2.3 kJ Mather type pulsed plasma focus device was used for the synthesis of a TiN/a-Si3N4 thin film at room temperature. The film was characterized using X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electron microscopy （SEM）, and atomic force microscopy （AFM）. The XRD pattern confirms the growth of polycrystalline TiN thin film. The XPS results indicate that the synthesized film is non-stoichiometric and contains titanium nitride, silicon nitride, and a phase of silicon oxy-nitride. The SEM and AFM results reveal that the surface of the synthesized film is quite smooth with 0.59 nm roughness （root-mean-square）.

关键词： plasma focus TiN/a-Si3N4 films X-ray diffraction

Study of Current Sheath Velocity and Its Distribution Using Tridimensional Magnetic Probe in Sahand plasma focus

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plasma Science and Technology 2015年第5期17卷 353-357页

作者： M.A.MOHAMMADI S.HEDYEH Department of Atomic and Molecular Physics Faculty of PhysicsUniversity of Tabriz Research Center of Astrophysics and Applied Physics University of Tabriz

The current sheath velocity in 0.25 Torr gas pressure of Filippov type plasma focus is studied experimentally. By using two tridimensional magnetic probes on top of the anode surface, the current sheath velocity is measured for argon, oxygen and nitrogen. Additionally, the effect of charging voltage on the current sheath velocity is studied in both axial and radial phases. We found that, the maximum current sheath velocities at both radial and axial phases are respectively 4.33 ± 0.28 （cm/μs） and 3.92 ± 0.75 （cm/μs） with argon as the working gas at 17 kV. Also, the minimum values of current sheath velocity are 1.48 ± 0.15 （cm/μs） at the radial phase and 1.14 ± 0.09 （cm/μs） at the axial phase with oxygen at 12 kV. The current sheath velocity at the radial phase is higher than that at the axial phase for all gases and voltages. In this study, variation of the full width half maximum （FWHM） of magnetic probe signals with voltage is investigated for different gases at radial and axial phases.

关键词： plasma focus tridimensional magnetic probe current sheath dynamics

Application　of　a　Double－Wollaston－prism　Laser　Differential　Interferometer　in　plasma　focus

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Chinese Journal of Lasers 1996年第5期B5卷 461-466页

作者： LU Mingfang YANG Tsinchi HAN Min (Tsinghua University, Beijing 100084, China) Tsinghua Univ Beijing China

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关键词： laser differential interferometry plasma focus