Includes bibliographical references and index. / The design and implementation of a method to software interface high level applications programs used for the control and monitoring of a Particle Accelerator is described. Effective methods of interfacing the instrumentation bus system with a Real time multitasking computer operating system were examined and optimized for efficient utilization of the operating system software and available hardware. Various methods of accessing the instrumentation bus are implemented as well as demand response servicing of the instruments on the bus.

<p> This thesis details the application of computational methods to the problem of determining custom data representations when building hardware accelerators for numerical computations. A majority of scientific applications which require hardware acceleration are implemented in IEEE-754 double precision. However, in many cases the error tolerance requirements of the application are much less than the accuracy which IEEE-754 double precision provides. By leveraging custom data representations, a more resource efficient hardware implementation arises thereby enabling greater parallelism and thus higher performance of the accelerator. </p> <p> The existing custom representation methods are unable to guarantee robust representations while at the same time adequately supporting ill-conditioned operators. Support for both of these scenarios is necessary for accelerating scientific calculations. To address this, we propose the use of a computational method based on Satisfiability-Modulo Theory (SMT). By capturing a calculation as a set of constraints, an SMT instance can be formulated which provides meaningful bounds even in the presence of ill-conditioned operators. At the same time, the analytical nature of SMT satisfies the need for robustness. Utilizing block vector arithmetic, our SMT approach is extended to provide scalability to large instances involving vector calculus which arise in scientific calculations. Atop this foundation, a unified error model is proposed which deals simultaneously with absolute and relative error, thereby providing the means of supporting both fixed-point and custom floating-point data types. Iterative algorithm analysis is leveraged to derive constraints for the SMT method. The application of the method to several scientific algorithms is discussed by way of case studies. </p> / Thesis / Doctor of Philosophy (PhD)

Particle accelerators are machines to accelerate and store charged particle beams, such as electrons or protons, to the energy levels for various scientific applications. There are three basic types of particle accelerators: linear accelerators (linac), storage-ring (or circular) accelerators, and recirculating accelerators. The third type, also the most recent one, is designed to accelerate a particle beam in a short section of linac, circulate and then continue to accelerate it for energy boost or decelerate it for energy recovery. The modern recirculating machines possess the advantages to both accelerate and preserve the beam with high beam quality, as well as efficiently reuse the accelerating components. As modern accelerators push toward the high-brightness or high-intensity frontier by demanding particles in a highly charged bunch to concentrate in an ever-decreasing beam phase space, the interaction amongst particles via their self-generated electromagnetic fields can potentially lead to coherent instabilities of the beam and thus pose significant challenges to the machine design and operation. Microbunching instability (MBI) has been one of the most challenging issues for such high-brightness or high-intensity beam transport, as it would degrade lasing performance in the fourth-generation light sources, reduce cooling efficiency in electron cooling facilities, and eventually compromise the luminosity of colliding beams in lepton or lepton-hadron colliders. The dissertation work will focus on the MBI in modern recirculating electron accelerators. The research attempts to develop a comprehensive theoretical formulation of MBI with aspects including among various degrees of freedoms the beam itself, the beamline lattice optics, and incorporation of all relevant collective effects that the beam encounters, for example the coherent synchrotron radiation (CSR) and the longitudinal space charge (LSC) effects. This dissertation includes the following seven themes: 1) Development and generalization of MBI theory to arbitrary linear lattices and coupled beams with constant and varying energies; 2) Construction of CSR impedance models from steady state to transient state and from high to low energy regime; 3) Numerical implementation of the developed theory as a fast and numerical-noise-free Vlasov solver and benchmarking with massive particle tracking simulation; 4) Exploration of multistage cascaded amplification mechanism of CSR microbunching development; 5) Control of CSR-induced MBI in multi-bend transport or recirculation arcs; 6) Study of more aspects of microbunched structures in beam phase spaces; and 7) Study of MBI for magnetized beams and confirming the suppression of MBI for a recent cooler design for Jefferson Lab Electron Ion Collider project. / Ph. D.

no abstract provided by author / Master of Science

Though modifications and improvements continue on the Virginia Polytechnic Institute electrostatic accelerator, the basic machine has been completed and put into operation. The emphasis thus far has been on experiments at energies below 750 kev and no attempt has been made to determine the maximum operating potential. This work describes the author's contributions to the overall project through the design and construction of many of the electronic control and instrumentation circuits. Through a study of the inelastic collisions of protons with fluorinet, a resolution of 9:1 key was determined. / Master of Science

Hardware-acceleration techniques continue to be used to boost the performance of scientific codes. To do so, software developers identify portions of these codes that are amenable for offloading and map them to hardware accelerators. However, offloading such tasks to specialized hardware accelerators is non-trivial. Furthermore, these accelerators can add significant cost to a computing system. Consequently, this thesis proposes a framework called GePSeA (General Purpose Software Acceleration Framework), which uses a small fraction of the computational power on multi-core architectures to offload complex application-specific tasks. Specifically, GePSeA provides a lightweight process that acts as a helper agent to the application by executing application-specific tasks asynchronously and efficiently. GePSeA is not meant to replace hardware accelerators but to extend them. GePSeA provide several utilities called core components that offload tasks on to the core or to the special-purpose hardware when available in a way that is transparent to the application. Examples of such core components include reliable communication service, distributed lock management, global memory management, dynamic load distribution and network protocol processing. We then apply the GePSeA framework to two applications, namely mpiBLAST, an open-source computational biology application and Reliable Blast UDP (RBUDP) based file transfer application. We observe significant speed-up for both applications. / Master of Science

Ph. D.

Coaxial plasma accelerators have been the subject of experimental and theoretical analysis since the 1950s. Theories have evolved that predict subsets of the measured data. This work separates coaxial plasma accelerator research into two broad categories classified by the ratio of accelerator discharge current to input gas flow rate. Devices that operate with this ratio above a particular threshold are called "starved" and the acceleration process is termed "“deflagration". Devices that operate below the threshold are called “over-fed" and the plasma undergoes a compressive energy conversion process termed "detonation". Over-fed (detonation) plasma accelerators add energy to the plasma through plasma heating and compression. The plasma exhaust velocity is limited to the magneto-sonic velocity which is nearly identical to the plasma Alfven velocity. Measured energy conversion efficiencies for detonation plasma accelerators have been typically less than 10%. Starved (deflagration) plasma accelerators add energy to the plasma by increasing the plasma kinetic energy. Thus, the plasma exhaust velocities measured in the deflagration accelerator exceed the plasma Alfven velocity by two orders of magnitude. Measured energy conversion efficiencies for the deflagration mode exceed 40%. Two additional sub-categories have been defined. The first is based on the number of acceleration stages. A single stage device processes neutral gas into the accelerated plasma. Multi-stage devices first ionize the neutral gas and then accelerate it to the final velocity. Finally, plasma accelerators with coaxial electrodes are classified by the interval in which the electrical energy is transformed into plasma energy. A new theory was developed to explain the deflagration plasma accelerator operation by examining the failures of previous magneto-hydro-dynamic based theories. The new theoretical treatment was used to develop a computer simulation of the deflagration plasma accelerator process. The theory and model were tested against experimental data for single and dual stage deflagration accelerator devices. With successful correlation achieved between the theory, computer model and experimental measurements, changes were made to the original accelerator, guided by modeling results. The new deflagration plasma accelerator was tested and the results closely matched the predictions for all key accelerator performance parameters. / Ph. D.

In view of the advantages of its type, the decision to construct a neutron source of the particle accelerator type was made. The purpose of this thesis is to survey the problems encountered in the construction of the source.

Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring. / text