Kinetic treatment of parallel gradient nonuniformity for the ICRF heating—A fourier integral approach

We study the generally nonlocal Vlasov‐Maxwell wave propagation and absorption problem for an arbitrarily nonuniform plasma. The Fourier transform of the nonlocal dielectric response kernel, K(r,k), is constructed by integration along particle orbits in the nonuniform field. Although a finite Larmor radius expansion of the transverse particle motion still applies, the phase integrals which comprise the usual plasma dispersion function are altered, containing an additional parameter characterizing the parallel field gradient. The use of realistic phase decorrelation estimates over a single bounce orbit leads to a reduction of the phase integrals to a tractible form. We numerically solve a 1‐D sheared field version of the resultant integral equation describing the mode conversion physics. Significant changes are found for small k∥ values. In addition, local absorption in the resonance zone appears to be stratified in conjunction with the rf‐particle phase correlation which occurs for particles passing through the localized resonance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87459/2/350_1.pd

Magnetic shielding and ohmic losses from finite thickness Faraday Shields

A calculation method is developed by which the magnetic field can be calculated for some simple cross‐section shapes of Faraday Shields with finite thickness.(AIP)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87353/2/71_1.pd

Hairpins in the conformations of a confined polymer

If a semiflexible polymer confined to a narrow channel bends around by 180 degrees, the polymer is said to exhibit a hairpin. The equilibrium extension statistics of the confined polymer are well understood when hairpins are vanishingly rare or when they are plentiful. Here we analyze the extension statistics in the intermediate situation via experiments with DNA coated by the protein RecA, which enhances the stiffness of the DNA molecule by approximately one order of magnitude. We find that the extension distribution is highly non-Gaussian, in good agreement with Monte Carlo simulations of confined discrete wormlike chains. We develop a simple model that qualitatively explains the form of the extension distribution. The model shows that the tail of the distribution at short extensions is determined by conformations with one hairpin.Comment: Revised version. 22 pages, 7 figures, 2 tables, supplementary materia

Phase Control and Fast Start-Up of a Magnetron Using Modulation of an Addressable Faceted Cathode

The use of an addressable, faceted cathode has been proposed as a method of modulating current injection in a magnetron to improve performance and control phase. To implement the controllable electron emission, five-sided and ten-sided faceted planar cathodes employing gated field emitters are considered as these emitters could be fabricated on flat substrates. For demonstration, the conformal finite-difference time-domain particle-in-cell simulation, as implemented in VORPAL, has been used to model a ten-cavity, rising sun magnetron using the modulated current sources and benchmarked against a typical continuous current source. For the modulated, ten-sided faceted cathode case, the electrons are injected from three emitter elements on each of the ten facets. Each emitter is turned ON and OFF in sequence at the oscillating frequency with five emitters ON at one time to drive the five electron spokes of the π-mode. The emitter duty cycle is then 1/6th the Radio-Frequency (RF) period. Simulations show a fast start-up time as low as 35 ns for the modulated case compared to 100 ns for the continuous current cases. Analysis of the RF phase using the electron spoke locations and the RF magnetic field components shows that the phase is controlled for the modulated case while it is random, as typical, for the continuous current case. Active phase control during oscillation was demonstrated by shifting the phase of the electron injection 180° after oscillations started. The 180° phase shift time was approximately 25 RF cycles

Evaluating quality hospital service: The relationship of expectations and social support to patients\u27 perceptions

This study measured the degree to which customers were satisfied with the quality of hospital service they received while they were in-patients in a Connecticut hospital. The theoretical rationale for the study was based on Parasuraman et al.\u27s (1985) quality of service model that is supported by related total quality models.^ Subjects (N = 150) completed a 4-part, self-report attitudinal instrument, the Quality of Hospital Service in which they indicated their sex, age, education, insurance status, and employment status, expectations of their hospital stay (6-item instrument), perceptions of the medical service (16-item instrument), and perceived social support (6-item instrument). The Perceptions of Quality Hospital Service section of the QHS was adapted from the SERVQUAL instrument that was previously found to be reliable and valid in studies of service and retail organizations.^ The first research question was: What combination of variables define the factor structure of Perceptions of Quality Hospital Service? A factor analysis revealed that the Perceptions of Quality Hospital Service instrument defined a one-factor structure with high internal consistency. The second question was: What is the relationship of the independent variables (sex, employment status, and insurance status) with the perceived satisfaction level of quality hospital service as measured by the total score of Perceptions of Quality Hospital Service? An analysis using 3 one-way analyses of variance, indicated that there were no significant differences among subjects within the categorical groups and the dependent variable, Perceptions of Quality Hospital Service. The third question was: What combination of variables, Patients\u27 Expectations, Social Support, age, and years of education measure the variance of the perceived satisfaction level of quality hospital service as measured by the Perceptions of Quality Hospital Service? A hierarchical multiple regression analysis indicated that the variables Patients\u27 Expectations and Social Support explained 50% of the variance in the dependent variable.^ The results of this study are important because they underscore the relationship between patients\u27 expectations, social support, and perceptions of quality hospital service. The results, especially those regarding the relationship between expectations and the perceptions of hospital experience, are consistent with the research in Adult and Experiential Learning.

A Single-Frequency ECR Ion Source With a Large Uniformly Distributed Resonant Plasma Volume

An innovative technique for increasing ion source intensity is described which, in principle, could lead to significant advances in ECR ion source technology for multiply charged ion beam formation. The advanced concept design uses a minimum-B magnetic mirror geometry which consists of a multi-cusp, magnetic field, to assist in confining the plasma radially, a flat central field for tuning to the ECR resonant condition, and specially tailored mirror fields in the end zones to confine the plasma in the axial direction. The magnetic field is designed to achieve an axially symmetric plasma {open_quotes}volume{close_quotes} with constant mod-B, which extends over the length of the central field region. This design, which strongly contrasts with the ECR {open_quotes}surfaces{close_quotes} characteristic of conventional ECR ion sources, results in dramatic increases in the absorption of RF power, thereby increasing the electron temperature and {open_quotes}hot{close_quotes} electron population within the ionization volume of the source