The plasma focus is similar to the

The concept of magnetic plasma confinement was examined experimentally for the first time in systems in which plasma was produced by an electrical discharge in gas . A plasma focus (DPF) is a machine that produces, by electromagnetic acceleration and compression, a short-lived plasma that is hot and dense enough to cause nuclear fusion and the emission of X-rays and neutrons. The electromagnetic compression of the plasma is called a pinch. It was invented in 1954 by N.V. Filippov ,  and also independently by J.W. Mather in the early 1960s. The plasma focus is similar to the high-intensity plasma gun device (HIPGD) (or just plasma gun), which ejects plasma in the form of a plasmoid, without pinching it. A comprehensive review of the dense plasma focus and its diverse applications has been made by Krishnan in 2012.For many years , high-current pulse experiments of the plasma-focus (PF) type have been investigated in various laboratories because such discharges can easily generate hot and dense plasma which emits intense pulses of electromagnetic and corpuscular radiation . The attention is usually focussed on the emission of intense x-ray pulses as regards the electromagnetic radiation which provide information about the structure and characteristics of the PF pinch column, and can also be used for different technological applications.Numerous experiments done throughout the 1960s, 70s, and 80s on Plasma-Focus systems with different energy sources (capacitor banks), ranging from a few to several hundreds of kJ, and using deuterium as a working gas, showed a promising relationship between the total number of emitted neutrons and the energy of the capacitor bank supplied to these systemsAn investigation on the soft x rays emitted in a 2.2 kJ Mather-type dense plasma focus device using a multichannel diode spectrometer and a simple pinhole camera is reported. Emitted x rays associated with different shapes (hollow, solid, and hemispherical) of anode and in hydrogen/nitrogen gas medium are compared. The structure of x-ray emitting sites as well as x-ray yields were found to be strongly influenced by the shape of the anode and the filling gas pressure. The maximum yield of 2.2 J into 4? sr was obtained in the case of hemispherical anode in hydrogen gas medium. The x-ray pinhole images of the collapsed plasma with the hemispherical anode indicated spot-like structure having 500–800 ?m in diameter. On the contrary, other anode shapes showed columnar pinched structure of 8–10 mm in length and 1–2 mm in diameter. Results indicated that an appropriate design of the anode could enhance the x-ray yield by more than tenfold in a conventional low energy dense plasma focus device.A typical arrangement of Plasma-Focus (PF), regardless of whether it is a Filippov or Mather type of system, consists of the following basic elements . Capacitor bank with the capacity of C0 , which stores electrical energy. Electrical circuit containing low-inductive spark gaps, Is, and cables between the bank and the current collector. An anode separated from a cathod by a cylindrical insulator in the vacuum chamber . The operation of Plasma Focus Device is based on the pulsed electrical discharge through gases contained between two coaxial electrodes separated with an insulator . High voltage applied to the electrodes immersed in a low pressure (of the order of few Torrs) gas causes an electrical break-down along the insulator. Fast rise of the current (with ~1-5 us time scale) leads to the formation of a plasma sheath, which, driven by jxB force, moves along the electrodes towards their open end . A vacuum chamber often is used as the cathode in the Filippov system. The chamber, after reaching a high vacuum (of the order of 10-3 Pa), is filled with different types of gases depending on the nature of the experiments. In experiments relating to thermonuclear fusion, the chamber is filled with deuterium, and sometimes a low admixture of an inert gas (e.g. argon) is added for diagnostic purposes .The Plasma Focus system can be represented as an RLC circuit, in which the electrical energy initially stored in the capacitor bank, with a capacity of C0 , changes into the magnetic field energy of the current during shaping, separation from the insulator, and acceleration of the current sheath along the electrodes.The emission of neutrons from the plasma focus is the main indicator of the (D,D) fusion reaction yield in the Plasma-Focus system. The amount of neutrons generated in a (D,D) fusion reaction in volume V and during the lifetime of the plasma focus ?, assuming that plasma is in equilibrium at this time, can be expressed by the relationship , which corresponds quite well to the experimental data in a wide range of current intensities in plasma .