Wire array implosion experiments on the inductive storage generators GIT-4 and GIT-8

Baksht

Plasma Phys. Control. Fusion

et al. 2020

Filamentation is a type of magnetohydrodynamic instability that may develop in a currentcarrying plasma. It is supposed that filaments, individual current channels, are formed due to thermal instabilities. The growth of these instabilities is determined by the behavior of the electrical conductivity of the material depending on its thermodynamic parameters. If the conductivity increases with temperature, as is the case in a plasma, thermal instabilities should give rise to the formation of separate current channels. This paper presents an analysis of the development of thermal instabilities in imploding plasma liners performed in terms of small perturbation theory. The theoretical predictions are compared with the results of experiments conducted on the IMRI-5 facility at a current of amplitude up to 450 kA and rise time about 500 ns.

Section: R Umentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal filamentation instabilities developing in imploding plasma liners

Baksht

Plasma Phys. Control. Fusion

et al. 2020

“…For gas puffs, which can be fabricated as annular shells, this technique has been successful in improving the stagnated pinch and radiated output for argon K-shell loads. 9,[33][34][35] The same concept can be applied to wire arrays through the use of nested wire arrays, 24,36 where two cylindrical wire arrays are placed concentric to one another ͑see Fig. 1͒.…”

Section: Introductionmentioning

confidence: 95%

Large diameter (45–80mm) nested stainless steel wire arrays at the Z accelerator

et al. 2008

Experiments have been performed at the Z accelerator to elucidate the effects of initial load diameter on the radiated output of a 7keV wire array x-ray source. Nested wire arrays with initial outer diameters of 45–80mm were fielded, with the masses chosen to maintain a nominally constant coupling to the Z generator. The total radiated output decreased from ∼1.1MJ to <0.5MJ for the largest diameter arrays, while the >1keV and K-shell radiation decreased at both small and large diameters. The >1keV output peaked at ∼340kJ, while the K-shell yield peaked at ∼55kJ. The observed trends in radiated output and stagnated plasma parameters are consistent with a phenomenological K-shell scaling theory, and are reproduced in one-dimensional modeling, although multidimensional effects, such as, growth of the Rayleigh–Taylor instability, are observed in the experiments and appear to impact the stagnated plasma for the larger diameter arrays.

Plasma Phys. Control. Fusion

“…In Z-pinch plasmas, various types of magnetohydrodynamic instability may develop. The most dangerous of these are Rayleigh-Taylor instabilities whose growth is caused by the pressure of the magnetic field created by the current flowing through the pinch [2][3][4][5][16][17][18][19][20]. In terms of the MagLIF concept, to suppress this type of instability, it is supposed to use an external magnetic field whose induction vector is directed axially, that is parallel to the direction of the current.…”

Section: Introductionmentioning

confidence: 99%

Effect of the plasma self-radiation on the growth of thermal filamentation instabilities in imploding Z pinches

Oreshkin¹,

Oreshkin²

2021

The development of thermal filamentation (TF) instabilities in a current-carrying plasma shell under the action of the plasma self-radiation was analyzed in terms of a small perturbation theory. A stationary collisional radiative model was used to calculate the parameters of the bremsstrahlung, recombination radiation, and spectral line radiation. It has been shown that radiative losses can either enhance or weaken the growth of TF instabilities. The pattern of the effect is governed by the dependence of the energy lost by the plasma due to radiation, Q Rad, on the plasma temperature T. If Q Rad increases slower than ∼T, the radiative losses enhance TF instabilities. In the opposite case, that is when Q Rad increases faster than ∼T, the radiative losses lead to suppression of TF instabilities. When the energy lost due to radiation is greater than the Joule energy input, TF instabilities can be completely stabilized due to radiation. The plasma parameter ranges for which stabilization of TF instabilities may occur due to radiation have been found for aluminum and argon.