Tearing

About: Tearing is a research topic. Over the lifetime, 4015 publications have been published within this topic receiving 48121 citations. The topic is also known as: to tear & tear apart.

Rupture of rubber. I. Characteristic energy for tearing

Abstract: The resistance to tearing of a rubber vulcanizate is usually determined by loading in a specified manner a test-piece of the vulcanizate of standard shape, in which a notch has been produced, either in the molding process or by cutting the test-piece in a standard fashion. A wide variety of shapes of test-piece and notch and of methods of loading have been recommended by various authors (see, for example, Buist1).

Nonlinear growth of the tearing mode

Abstract: The resistive tearing mode is analyzed in the nonlinear regime; nonlinearity is important principally in the singular layer around k·B = 0. In the case where the resistive skin time τs is much longer than the hydromagnetic time τ H, exponential growth of the field perturbation is replaced by algebraic growth like t2 at an amplitude of order (τ H / τ S )4/5. Application of the theory to the unstable tearing modes of a tokamak with a shrinking current channel yields good agreement with the observed amplitudes of the m ≥ 2 oscillations. The analysis excludes the very long wavelength mode, and m = 1 in the tokamak, for which the “constant‐Ψ” approximation is invalid.

Tearing mode in the cylindrical tokamak

Abstract: Detailed computational results are presented on the stability and radial distribution of linear tearing modes in cylindrical tokamaks of various radial profiles. In the case of a skin‐current profile, a “double tearing mode”, with two points of discontinuity in the radial magnetic field perturbation is found. An analytical method is also derived for comparison of the stability of different radial profiles. It is further shown that the tearing mode can be driven by finite electron viscosity, as well as by the usual finite resistivity mechanism.

Kinetic theory of tearing instabilities

Abstract: The transition of the tearing instability from the collisional to the collisionless regime is investigated kinetically using a Fokker–Planck collision operator to represent electron‐ion collisions. As a function of the collisionality of the plasma, the tearing instability falls into three regions, which are referred to as collisionless, semi‐collisional, and collisional. The width Δ of the singular layer around k⋅B0=0 is limited by electron thermal motion along B0 in the collisional and semi‐collisional regimes and is typically smaller than ρi, the ion Larmor radius. Previously accepted theories, which are based on the assumption Δ≫ρi, are found to be valid only in the collisional regime. The effects of density and temperature gradients on the instabilities are also studied. The tearing instability is only driven by the temperature gradient in the collisional and semi‐collisional regimes. Numerical calculations indicate that the semi‐collisional tearing instability is particularly relevant to present day high temperature tokamak discharges.