Related papers: Can surface cracks and unipolar arcs explain break…

Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma…

We describe breakdown in 805 MHz rf accelerator cavities in terms of a number of self consistent mechanisms. We divide the breakdown process into three stages: 1) we model surface failure using molecular dynamics of fracture caused by…

Although used in the design and costing of large projects such as linear colliders and tokamaks, the theory of vacuum arcs and gradient limits is not well understood. Almost 120 years after the isolation of vacuum arcs, the exact mechanisms…

The occurrence of vacuum arcs or radio frequency (rf) breakdowns is one of the most prevalent factors limiting the high-gradient performance of normal conducting rf cavities in particle accelerators. In this paper, we search for the…

Continuing the description of rf vacuum arcs from an earlier paper, we describe some aspects of the interaction of vacuum arcs that involve the surface. This paper describes aspects of plasma materials interactions that affect the arc and…

Although a general model of vacuum arcs and gradient limits would be widely useful, roughly 120 years after the first good experimental data on these arcs, this important field continues to be unsettled. This problem is a limitation in a…

We are developing a model of vacuum arcs. This model assumes that arcs develop as a result of mechanical failure of the surface due to Coulomb explosions, followed by ionization of fragments by field emission and the development of a small,…

We review recent theoretical progress on the dynamics of brittle crack fronts and its relationship to the roughness of fracture surfaces. We discuss the possibility that the intermediate scale roughness of cracks, which is characterized by…

The problem of crack pattern formation due to thermal shock loading at the surface of half-space is solved numerically using two-dimensional boundary element method. The results of numerical simulations with 100-200 random simultaneously…

X-band accelerator structures meeting the Next Linear Collider (NLC) design requirements have been found to suffer vacuum surface damage caused by radio frequency (RF) breakdown, when processed to high electric-field gradients. Improved…

Unstable growth of cracks (rough crack surface and crack branching) in dynamic fracture has long been observed in various materials. Until now, there was no universally agreed upon explanation for these instabilities. Here, we demonstrate…

An investigation of ultrashort pulsed laser induced surface modification due to conditions that result in a superheated melted liquid layer and material evaporation are considered. To describe the surface modification occurring after…

Patterns on broken surfaces are well-known from everyday experience, but surprisingly, how and why they form are very much open questions. Well-defined facets are commonly observed1-4 along fracture surfaces which are created by slow…

We investigate the breakdown of disordered networks under the action of an increasing external---mechanical or electrical---force. We perform a mean-field analysis and estimate scaling exponents for the approach to the instability. By…

Breakage is generally understood in mechanical terms, yet nano-structures can rupture not only under external loads but also via thermal activation. Here we treat in a general framework the statistical mechanics of thermally induced…

While of paramount importance in material science, the dynamics of cracks still lacks a complete physical explanation. The transition from their slow creep behavior to a fast propagation regime is a notable key, as it leads to full material…

A phase field model of a crack front propagating in a three dimensional brittle material is used to study the fractographic patterns induced by the branching instability. The numerical results of this model give rise to crack surfaces that…

During brittle crack propagation, a smooth crack front curve frequently becomes disjoint, generating a stepped crack and a material ligament that unites the newly formed crack fronts. These universal features fundamentally alter the…

Experiments on fracture surface morphologies offer increasing amounts of data that can be analyzed using methods of statistical physics. One finds scaling exponents associated with correlation and structure functions, indicating a rich…

Fractal structures appear in a vast range of physical systems. A literature survey including all experimental papers on fractals which appeared in the six Physical Review journals (A-E and Letters) during the 1990's shows that experimental…