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Experimental Results of a Plasma Wakefield Accelerator Using Multiple Electron Bunches
Where: IEEE European Particle Accelerator Conference, Genoa, Italy When: June 2008
Also published in the conference proceedings
We present some preliminary experimental results of a plasma wakefield accelerator technique which utilizes multiple electron bunches in order to drive a plasma wave. The experiments were performed at the Accelerator Test Facility of Brookhaven National Laboratory where 5-8 equidistant bunches with a spacing which was varied between 100-200μm were fed into a 6mm-long capillary discharge plasma. By varying the time delay of the bunches with respect to the discharge different plasma densities could be tuned, and the effects of the plasma on the bunches were recorded. Such multiple bunch schemes are of great interest because they can provide increased efficiencies and high transformer ratios for advanced accelerators.
Like (1)Where: University of Southern California When: December 2007
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This presentation is a literature survey that summarizes the major evidence that support the existence of Dark Matter. I analyze the galaxy rotation curves, the motions of galaxies inside clusters, the baryonic mass density estimated from Big Bang Nucleosynthesis, the data accumulated from the cosmic microwave background radiation (WMAP, COBE) and finally the dark matter estimates from gravitationally lensed data such as the bullet cluster. Alongside I present some proof for the existence of Dark Energy, as well as evidence that the universe is flat.
Cellulosic Ethanol and the future of biofuels: From carbohydrates to hydrocarbons
Where: University of Southern California When: November 2007
This report is aimed at providing a summary of the field of biofuels: the production of liquid fuels from plants. Biofuels are not aiming at solving the world energy problem, but rather at providing a viable alternative to the transportation fuels which are presently derived almost in their entirety from imported oil. Rising oil prices, instabilities in the oil-producing regions of the world and greenhouse gas emissions from fossil fuels provide the motivation behind a field in ferment.
As opposed to other renewable intermittent energy technologies such as photovoltaic cells and wind farms, which require (currently inefficient) electrical storage mechanisms in order to function reliably over long periods of time, plants absorb solar energy and store it chemically inside their biomass. It is estimated by our report that 1TW of average power is stored into available for biofuel production biomass in the United States only (the global power consumption is during the year 2007 at 15TW). Even if a small fraction of that stored energy can be retrieved from the biomass, a significant portion of motor fuel could be replaced.
The first chapter summarizes the present global situation in terms of energy demand, CO2 emissions and oil consumption. Chapter 2 provides a basic background on biofuels and examines their potential from an energy perspective. Chapter 3 provides an overview of the biofuel landscape in the United States, which is currently relying on ethanol fuel derived from corn kernels to provide 3% of its transportation fuels, although this type of ethanol could not be expanded into large scale. Chapter 4 examines the details of producing ethanol from the cellulose molecules that comprise the plant walls, which, if harnessed properly, can have much higher efficiencies and energy outputs than crop-derived ethanol because it can consume non-traditional biomass which is not used directly for other purposes. Chapter 5 describes briefly other biofuel production techniques, such as Biodiesel (popular in Germany), sugarcane-derived ethanol (successful in Brazil), Biobutanol and algae cultivation. Finally, we summarize the report in chapter 6.
The document was prepared as a requirement of the ENE505 class at USC (Energy and the Environment) under prof. Ravindra.
Plasma Wakefield Acceleration Utilizing Multiple Electron Bunches
Where: IEEE Particle Accelerator Conference, Albuquerque, NM When: June 2007
Also published in the conference proceedings
We investigate various plasma wakefield accelerator schemes that rely on multiple electron bunches to drive a large amplitude plasma wave, which are followed by a witness bunch at a phase where it will sample the high acceleration gradient and gain energy. Experimental verifications of various two bunch schemes are available in the literature; here we provide analytical calculations and numerical simulations of the wakefield dependency and the transformer ratio when M drive bunches and one witness bunch are fed into a high density plasma, where M is between 2 and 10. This is a favorable setup since the bunches can be adjusted such that the transformer ratio and the efficiency of the accelerator are enhanced compared to single bunch schemes. The possibility of a five bunch ILC afterburner to accelerate a witness bunch from 100 GeV to 500 GeV is also examined.
Plasma Simulations and Multibunched Electron Beam Diagnostics
Where: 12th Advanced Accelerator Concepts Workshop, Lake Geneva, WI When: August 2006
Also published in the conference proceedings
In the multibunch plasma wakefield acceleration experiment at the Brookhaven National Lab's Accelerator Test Facility a 45 MeV electron beam is initially modulated through the IFEL interaction with a CO2 laser beam at 10.6 µm into a train of short microbunches, which are spaced at the laser wavelength. It is then fed into a high-density capillary plasma with a density resonant at this spacing (1.0 × 1019 cm-3). The microbunched beam can resonantly excite a plasma wakefield much larger than the wakefield excited from the non-bunched beam. Here we present plasma simulations that confirm the wakefield enhancement and the results of a series of CTR measurements performed of the multibunched electron beam.
A Multibunch Plasma Wakefield Accelerator
Where: IEEE Particle Accelerator Conference, Knoxville, TN When: June 2005
Also published in the conference proceedings
We investigate a plasma wakefield acceleration scheme where a train of electron microbunches feeds into a high density plasma. When the microbunch train enters such a plasma that has a corresponding plasma wavelength equal to the microbunch separation distance, a strong wakefield is expected to be resonantly driven to an amplitude that is at least one order of magnitude higher than that using an unbunched beam. PIC simulations have been performed using the beamline parameters of the Brookhaven National Laboratory Accelerator Test Facility operating in the configuration of the STELLA inverse free electron laser (IFEL) experiment. A 65 MeV electron beam is modulated by a 10.6 μm CO2 laser beam via an IFEL interaction. This produces a train of ~90 microbunches separated by the laser wavelength. In this paper, we present both a simple theoretical treatment and simulation results that demonstrate promising results for the multibunch technique as a plasma-based accelerator.
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