1.6 Dusty plasma in fusion devices

The working conditions of nuclear fusion devices are such that the fuel of these devices must be heated up to heat fuel in nuclear fusion devices heat in the range of <sup>100</sup> <sup>10</sup><sup>8</sup> K temperature, at this temperature the fuel is in the plasma state. The temperature of the plasma is very high, and materials are vaporized that contact with it, that's why plasma must be confined kept in the magnetic fields. In the Tokamak reactor fuel is use in the range of grams (g), so it is a very safe device. The solid impurities are known as "dust" were also found and investigate Scrape-Off Layer transport that is a key element of edge physics research program. For safety precautions against the dust particles, it is very significant for engineers to predict where the quantity of dust particles increases. To resolve the dust transport problem in fusion devices it is necessary for physicists to develop a fully accurate dust transport code (DTC) [29]. It is also required to calculate the plasma parameters from geometrical relations and engineering constraints of nuclear fusion Tokamak device. Plasma density (n), pressure (p), temperature (T), energy confinement time, β (normalized plasma pressure) as a function of α (minor radius of plasma) are the basic main plasma parameters. In addition, some plasma parameters such as plasma current, bootstrap fraction and kink safety factor are required for a plasma physicist in order to understand Tokamak process. The reactor demands toroidal current I to achieving high energy confinement time (very large) for ignition [3, 27]. There are several techniques used for heating plasma in Tokamak. The most common technique use to heat plasma is Ohmic heating, neutral beam injection, RF heating. The fusion plasma has such as high temperature so that they emit little visible light [30, 31].

#### 1.7 Waves spectra in dusty plasma

To understand dynamical information and basic properties of gas, liquids, and solids, it is compulsory to study the basic two phenomena such as phase transition Wave Spectra in Dusty Plasmas of Nuclear Fusion Devices DOI: http://dx.doi.org/10.5772/intechopen.91371

and waves [32]. Dust particles in SCDPs support longitudinal (compressional) waves, also known as dust acoustic waves (DAWs) and transverse waves (shear) [13]. The propagations of longitudinal modes are faster than the transverse mode in the crystalline phase of dusty plasma. The WCDPs does not sustain the transverse wave and only sustain longitudinal waves. The compressional electrostatic waves and DAWs have low-frequency modes due to a larger mass of dust particles. In order to study the thermal motion of dust particles through MD simulation and it was found that cut off wave number is calculated for transverse mode near the solidification phase of dusty plasma [33]. The generalized hydrodynamics (GHD) model of the equation is predicted by the existence of transverse wave mode in the liquid and strong coupling regimes and dispersion properties of longitudinal modes [19]. Investigation of dusty longitudinal waves (DLWs—dust lattice waves) in twodimensional bi-crystal in an arbitrary direction and it was found that hybrid modes have both components along with transverse and longitudinal directions. The hybrid modes become purely transverse to longitudinal waves for the angle of propagation is 0 or π/2 [34]. Background of the colloidal suspension liquid exerts large friction on the motion of charged particles than the background of dusty plasma gases. Due to low friction between charged particles in the gas phase of dusty plasma waves damped slowly. The complex (dusty) plasma the current correlation functions of complex (dusty) plasma are classified into the longitudinal current and transverse current, also known as longitudinal and transverse (shear) wave's mode. In the classical fluids, when k approaches zero then longitudinal modes known as acoustic modes. Strongly coupled plasma in the liquid phase supports shear maintained transverse mode. In SCDPs, when k approaches zero then transverse modes are also considered approach as acoustic modes [35] (Figure 1).

The uniform liquid phase does not support transverse modes of waves. The reason for this is to ignore the migration of diffusion damping. For isotropy liquid, the transverse mode approaches the same Einstein frequency ω<sup>E</sup> as a longitudinal mode, when the wavenumber k approaches to infinite. The current correlation functions of DPs are studied theoretically, numerically and experimentally.

#### Figure 1.

Directions of longitudinal and transverse waves in DPs relative to the direction of wave numbers vectors. The direction of the wave vector shows that direction of CL(k, t) is along the wave vector and direction of CT(k, t) is perpendicular to the wave vector (k) [36].

The results are in good agreement with the theoretical prediction, in support of simulation measurements and also verified by experiments [14, 16, 24].
