Neutron and Proton Diagnostics for Pulsed Plasma Fusion Devices
This chapter describes some techniques and diagnostics for neutron and proton detection. It is more focused on DD fusion reaction products that comprise ~2.5 MeV neutron and ~3 MeV proton. Moreover, due to authors’ experience, it is tried to elaborate som
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Neutron and Proton Diagnostics for Pulsed Plasma Fusion Devices Alireza Talebitaher and Stuart V. Springham
6.1
Introduction
There are several pulsed plasma devices which can be used for fusion reaction such as Tokamak, Stellarator, pinch plasmas, etc., which work on the basis of magnetic confinement and also laser or ion beam-driven fusion systems which work on the basis of inertial confinement. The dense plasma focus (DPF) can be used as a magnetic fusion device due to its high plasma density and temperature, intense fusion products and simple structure. Based on the authors’ experiences in DPFs in different range of storage energy from sub-kJ to MJ devices, for neutron and proton diagnostics from pulsed plasma fusion devices, this chapter is mainly focused on deuterium–deuterium (DD) fusion reaction in DPF. The DPF device is a pulsed electrical discharge in different gases which was discovered independently by Mather [1] and Filippov [2]. Although these two systems were different in terms of constructional geometries, they were very similar as regards the dynamics of the current sheath and in the scaling laws [3] for neutron yield, X-ray and other kinds of emission. Since then, DPF devices have been built with energies ranging from a few joules to a few mega-joules with a consequent variation in the physical size. The main difference between Mather-type and Filippov-type DPF is in the electrode dimension and the aspect ratio (diameter/length) of the anode. The Mather-type device has an anode aspect ratio less than 1 (typically 0.25), while for the Filippov-type device the typical aspect ratio is around 5. Physicists are interested in the Plasma Focus (PF) because of the high ns value for the pinched plasma (where n is the particle density *1019 cm−3 and s is the confinement time *50 ns, giving ns = 5 1011 s cm−3), and bursts of fusion neutrons when operated in deuterium. However, to reach ignition in a thermonuA. Talebitaher (&) S.V. Springham National Institute of Education, Nanyang Technological University, Singapore, Singapore e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2017 R.S. Rawat (ed.), Plasma Science and Technology for Emerging Economies, DOI 10.1007/978-981-10-4217-1_6
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clear reaction requires fulfilling the Lawson Criterion of ns greater than 3 1014 s cm−3. Also the hot (*1 keV) dense plasma emits abundant soft and hard X-rays, especially when operated with high-Z gases like neon or argon. The PF has a very complex behavior and exhibits a rich variety of plasma phenomena. The PF is essentially a two-dimensional Z-pinch formed on, or near, the axis at the end of a coaxial plasma accelerator. The Filippov machine was developed as a modification of the straight Z-pinch and the Mather-type device was modified from the coaxial plasma gun.
6.1.1
Fusion Reactions in Plasmas
Among all of the possible fusion reactions which are shown in Table 6.1, DT reaction is the best candidate for future power plant based on fusion; however, obtainin
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