Chamber pressure

About: Chamber pressure is a research topic. Over the lifetime, 2988 publications have been published within this topic receiving 30725 citations.

Repressurization following eruption from a magma chamber with a viscoelastic aureole

Abstract: I analyze an approximate solution for spherical magma chambers (radius R1) surrounded by Maxwell viscoelastic shells (radius R2) in elastic half-spaces following a sudden decrease in pressure. Mass flux into the chamber is proportional to the pressure difference between a deep source and chamber, P∞−p(t). Solutions depend on R2/R1, ≡βc/(βm+βc), where βm,βc are magma and chamber compressibilities, the relaxation time tR, and the recharge time for the elastic system, τ. Without recharge the system exhibits either post-eruptive deflation or, for incompressible magmas, partial reinflation. More generally immediate post eruptive inflation is favored by large ,tR/τ and small R2/R1. With short tR and large the time for magma chamber pressure to recover increases significantly. Post-eruptive creep increases the chamber pressure, decreasing the pressure gradient driving recharge, delaying pressure recovery. Following eruption the hoop stresses, which are initially compressive, relax toward the radial stress causing them to go through a local (relative tension) maximum. The magma pressure in excess of the dike normal compression at the chamber wall, can recover to pre-eruptive values well before the chamber pressure or erupted mass recovers. This suggests that dikes could nucleate at the chamber margin well before sufficient pressure has recovered to drive them far from the chamber. For some parameters co-eruptive deflation has not fully recovered when the magma overpressure relative to hoop stress in the elastic region is restored to pre-eruptive values, a condition assumed to be sufficient for eruption.

Plasma etching of high dielectric constant materials on silicon in halogen chemistries

Abstract: Plasma etching of ZrO2 and HfO2 was studied in BCl3/Cl2 plasmas, as functions of the ion energy, chamber pressure, microwave power, and gas compositions. MClx is found to be the major etching product in Cl2 plasmas while MBxCly is the major etching product in BCl3 plasmas. The etching selectivity to Si is increased at lower ion energies and higher electron temperatures. Increasing microwave powers and reducing chamber pressures in BCl3/Cl2 plasmas increased the Cl and BCl2+ densities in the gas phase and consequently increased the metal oxide etch rate. A phenomenological model that takes into account the Cl density, BCl2+ density, and metal oxygen bond strength is proposed to describe the etch rate of ZrO2 and HfO2 in pure BCl3 plasmas as functions of the ion energy, microwave power, and chamber pressure. More accurate Cl flux measurement is needed to improve the model predictions.

Formation tester with improved sample collection system

Abstract: This invention provides a formation evaluation tool for collecting a formation fluid in a chamber at a predetermined pressure and for maintaining the pressure of the collected fluid at a desired level during the retrieval of the chamber to the surface. The formation fluid is pumped into the chamber while a piston exposed to the hydrostatic pressure maintains the chamber pressure at the hydrostatic pressure. During retrieval of the chamber, the pressure in the chamber is maintained at a predetermined level by pumping wellbore fluid to the piston. A control unit at the surface is utilized for controlling the operation of the formation tool.