Fine grain separation for the production of biomass fuel from mixed municipal solid waste.

The main goal of the project MARSS (Material Advanced Sustainable Systems) is to build a demonstration plant in order to recover a renewable biomass fuel suitable for the use in biomass power plants out of mixed municipal solid waste (MMSW). The demonstration plant was constructed in Mertesdorf (Germany), working alongside an existing mechanical-biological treatment plant, where the MMSW is biological dried under aerobe conditions in rotting boxes. The focus of the presented sorting campaign was set on the processing of fine grain particles minor than 11.5mm which have the highest mass content and biogenic energy potential of the utilized grain size fractions. The objective was to produce a biomass fuel with a high calorific value and a low content of fossil (plastic, synthetic) materials while maximizing the mass recovery. Therefore, the biogenic components of the dried MMSW are separated from inert and fossil components through various classification and sifting processes. In three experimental process setups of different processing depths, the grain size fraction 4-11.5mm was sifted by the use of air sifters and air tables.

Frustrated tunnel ionization of noble gas dimers with Rydberg-electron shakeoff by electron charge oscillation.

Strong field single ionization of homo- and heteronuclear noble gas dimers with ultrashort infrared laser pulses is experimentally investigated. A pronounced photoelectron yield maximum is found for dimers in the momentum range |p|≤0.1 a.u. which is absent for the corresponding monomer. This yield enhancement can be attributed to a new two-step strong field ionization mechanism active only in the dimers. In the first step, frustrated tunnel ionization at one of the atomic centers populates Rydberg states, which then become ionized in a second step through charge oscillation within the dimer ion core.

Agile linear interferometric method for carrier-envelope phase drift measurement.

A bandwidth-independent and linear interferometric method for the measurement of the carrier-envelope phase drift of ultrashort pulse trains is demonstrated. The pulses are temporally overlapped in a resonant multiple-beam interferometer. From the position of the spectral interference pattern, the relative carrier-envelope phase between two subsequent oscillator pulses is obtained at data acquisition rates up to 200 Hz. Cross calibration has been performed by f-to-2f interferometry in two independent experiments. The optical length of the interferometer has been actively stabilized, leading to a phase jitter of 117 mrad (rms). These results indicate a reduced noise and quicker data acquisition in comparison with previous linear methods for measuring the carrier-envelope phase drift.

Carrier-envelope phase stabilization with sub-10 as residual timing jitter.

We demonstrate carrier-envelope phase (CEP) stabilization of a mode-locked Ti:sapphire oscillator with unprecedented timing jitter of eight attoseconds. The stabilization performance is obtained by a combination of two different stabilization approaches. In a first step the drift of the CEP is stabilized with a conventional feedback loop by means of controlling the oscillator pump power with an acousto-optic modulator (AOM). In a second step we utilize a recently developed feed-forward type stabilization scheme which has a much higher control bandwith. Here an acousto-optic frequency shifter (AOFS) produces the stabilized output in the first diffraction order. Moreover, we present numerical results on the optimization of the length of the photonic crystal fiber, which is used to generate an octave-spanning spectrum, in order to optimize the sensitivity in the f-to-2f interferometers.

An evaluation of the vapor phase catalytic ammonia removal process for use in a Mars transit vehicle.

This article describes the design specification of the Vapor Phase Catalytic Ammonia Removal (VPCAR) process and the relative benefits of its utilization in a Mars Transit Vehicle application. The VPCAR process is a wastewater treatment technology that combines distillation with high-temperature catalytic oxidation of volatile impurities such as ammonia and organic compounds.

Solid waste processing in a CELSS: nitrogen recovery.

Life support technologies are being developed for long-duration space missions at NASA Ames Research Center as part of the Controlled Ecological Life Support System (CELSS) Program. The primary goal of the CELSS Program is to develop small-scale ecological systems, a CELSS, that mimic ecological systems on Earth. This small-scale replica CELSS can provide all of the necessary life support functions and recycle nearly 100% of the waste products. A CELSS will use plants to purify air, clean water, and generate food for a human habitat. Human and plant waste products will be converted to useful products and reintroduced into the plant and human habitats for consumption. Both physical/chemical and biological waste-processing systems may be utilized to recycle waste materials. Recovering nitrogen from waste products is a major concern because nitrogen is an important nutrient for plants and humans. This article will outline plant selection requirements and waste-processing requirements, characterize waste streams, and discuss the potential physical/chemical waste processors used to process the wastes and the fate of nitrogen as a result of the process employed.

Controlled Ecological Life Support Systems (CELSS) flight experimentation.

The NASA CELSS program has the goal of developing life support systems for humans in space based on the use of higher plants. The program has supported research at universities with a primary focus of increasing the productivity of candidate crop plants. To understand the effects of the space environment on plant productivity, the CELSS Test Facility (CTF) has been been conceived as an instrument that will permit the evaluation of plant productivity on Space Station Freedom. The CTF will maintain specific environmental conditions and collect data on gas exchange rates and biomass accumulation over the growth period of several crop plants grown sequentially from seed to harvest. The science requirements of the CTF will be described, as will current design concepts and specific technology requirements for operation in micro-gravity.