Ballistic collisions

In ballistic collision processes, the mean free path of the colliding objects is large compared with their size their motion can be represented by linear trajectories instead of the random walk used in DLA. Primary particles colliding with a fixed agglomerate penetrate more deeply into the interior of the agglomerate than in DLA and produce very compact structures... 

In the streaming step, the solvent particle trajectories are ballistic. Collisions are introduced by sorting the particles into cubic lattice cells and performing a stochastic rotation of the relative velocities in each cell. In contrast to DPD, the SRD method acts on all particles within the same collision cell. 

Fig. 1. The ballistic interactions of an energetic ion with a sohd. Depicted are sputtering events at the surface, single-ion /single-atom recoil events, the development of a collision cascade involving a large number of displaced atoms, and the final position of the incident ion. ° = normal atom ...

In a recent study, Huan et al. [25] performed NM R experiments in vibrofluidized beds of mustard seeds in which the small sample volume allowed pulses short enough that displacements in the ballistic phase were distinguishable from those in the diffusion phase. In this case, the average collision frequency is measured directly, bypassing the uncertainty of the multiplicative factor mentioned above. These workers also measured the height dependence of the granular temperature profile. 

In 1985. two research institutions (IBM and AT T Bell Laboratories) reported that electrons can travel through a semiconductor without being slowed by collisions (ballistically). The report was based upon experimental data showing a ballistic peak in the electron energy spectra of gallium arsenide (GaAs) test devices. Tins is reported in more detail in article on Arsenic. 

Ballistic and Dissociative Rare-Gas Atom-Halogen Molecule Collisions, M. Ben-Nun, T. Raz and R. D. Levine, Chem. Phys. Lett. 220, 291 (1994). 

Ballistic transport—Movement of a carrier through a semiconductor without collisions, resulting in extraordinary electrical properties. Carriers—Charge-carrying particles in semiconductors, electrons, and holes. 

Two of the most common classes of particle-dynamic simulations are termed hard-particle and soft-particle methods. Hard-particle methods calculate particle trajectories in response to instantaneous, binary collisions between particles and allow particles to travel ballistically between collisions. This class of... 

The development of powerful computers a few years after these pioneer calculations resulted in a more detailed picture of the processes occurring in a collision cascade [48]. These simulations showed that there are two main stages in the process of transferring energy from the energetic atom to the lattice. In the first stage, called the ballistic or collisional phase, the energy is... 

In addition to recoil mixing, other ballistic phenomena are possible during ion irradiation and implantation. For example, enhanced atomic mixing can occur when multiple displacements of target atoms result from a single incident ion. In the multiple displacement process, an initially displaced target atom (primary recoil) continues the knock-on-atom processes, producing secondary recoil atom displacements which in turn displace additional atoms. The multiple displacement sequence of collision events is commonly referred to as a collision cascade. 

The temperature region of surface kinetic control expands at lower pressures. Surface kinetics also can be attained by increasing the gas flow velocity. At low gas flow velocities, the deposition is fully thermodynamically controlled. A substantial increase of the gas flow will push the operation to enter the mass transport controlled regime. Finally, surface kinetic control is reached at yet still higher gas flow velocities. In ultra-high vacuum OMMBE processes the molecules entering the reactor from the source behave ballistically, i. e., they travel to the substrate without collisions either with other molecules or the reactor walls. This is termed the molecular flow regime. In this unique case, neither convection, either forced or natural, nor diffusion, plays a role in... 

Loesch H J and Herschbach D R 1972 Ballistic mechanism for vibrational and rotational energy transfer in Ar + Csl collisions J. Chem. Phys. 57 2038-50... 

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