Does the Fed cause Christmas?

A discussion of the relationship between money and output, with emphasis on the possibility that changes in output precede changes in money.Money supply ; Business cycles

Money, inflation and sectoral shifts

A presentation of a sectoral-shifts model with money that explains the short-run Phillips curve and predicts a long-run positive relationship between inflation and unemployment.Unemployment ; Inflation (Finance) ; Monetary theory

Why we don't know whether money causes output

An examination of the commonly accepted positive correlation between money and real output, including a review of several models of business cycles and an explanation of how money can be neutral and yet still appear to affect real output.Business cycles ; Money

Magnification effects and acyclical real wages

An analysis of a one-period, two-sector model in which firms must pay a fixed cost of hiring. The authors show that this type of model results in more employment variability and less-procyclical wages than do models without fixed hiring costs.Business cycles ; Wages ; Employment (Economic theory)

Study of the conditions for spontaneous H-mode transitions in DIII-D

A series of scaling studies attempting to correlate the H(high)-mode power threshold (P{sub TH}) with global parameters have been conducted. Data from these discharges is also being used to look for dependence of P{sub TH} on local edge parameters and to test theories of the transition. Boronization and better operational techniques have resulted in lower power thresholds and weaker density scaling. Neon impurity injection experiments show that radiation also plays a role in determining P{sub TH}. A low density threshold for the L(low)-H(high) transition has been linked with the locked mode low density limit, and can be reduced with the use of an error field correcting coil. Highly developed edge diagnostics, with spatial resolution as low as 5 mm, are used to evaluate how the power threshold depends on local edge conditions. Preliminary analysis of local edge conditions for parameter scans of n{sub e}, B{sub T}, and I{sub p} in single-null discharges, and the X-point imbalance in double-null discharges-show that, just before the transition to H-mode, the edge temperatures near the separatrix are approximately constant at 100 < T{sub i} < 220 eV and 35 < T{sub e} < 130 eV, even though the threshold power varied from 1.5 to 14 MW. During a density scan, the edge ion collisionality, v{sub *i}, varied from 2 to 17, demonstrating that a transition condition as simple as v{sub *i} = constant is inconsistent with the data. The local edge parameters of n{sub e}, T{sub e}, and T{sub i} do not always follow the same global scaling as P{sub TH}. Therefore, theories of the L-H transition need not be constrained by these scalings

DASI Three-Year Cosmic Microwave Background Polarization Results

We present the analysis of the complete 3-year data set obtained with the Degree Angular Scale Interferometer (DASI) polarization experiment, operating from the Amundsen-Scott South Pole research station. Additional data obtained at the end of the 2002 Austral winter and throughout the 2003 season were added to the data from which the first detection of polarization of the cosmic microwave background radiation was reported. The analysis of the combined data supports, with increased statistical power, all of the conclusions drawn from the initial data set. In particular, the detection of E-mode polarization is increased to 6.3 sigma confidence level, TE cross-polarization is detected at 2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit well below the level of the detected E-mode polarization. The results are in excellent agreement with the predictions of the cosmological model that has emerged from CMB temperature measurements. The analysis also demonstrates that contamination of the data by known sources of foreground emission is insignificant.Comment: 13 pages Latex, 10 figures, submitted to Ap

Optical Design for Li Beam Zeeman Polarimetry Measurements on Diii-D

Measurements of the magnetic field pitch angle are obtained from the polarization characteristics of the {sigma} component of the Zeeman triplet of Li emission at 670.8 nm. A four element optical system images a horizontal Li beam on an array of 3 x 32, 1 mm diam. optical fibers, providing 32 spatial channels with 5 mm radial resolution in the plasma. Low Verdet constant glass is used for all optical elements near the DIII-D vessel to minimize the effects of Faraday rotation caused by stray magnetic fields. Before entering the fiber optics, the light passes through two crossed (45 degrees) photoelastic modulators (PEM) and a linear polarizer, which convert the various polarization states into an intensity modulated signal at the fundamental and 2nd harmonic of the PEM frequencies. For each spatial channel, light from a three fiber bundle is collimated and passes through a temperature tuned etalon (free spectral range, FSR = 0.3 nm; finesse, F = 5.7) in order to select only one {sigma} line of the triplet. The FSR is large enough to adequately cover the expected Zeeman triplet and small enough to achieve a low bandwidth (0.06 nm) at reasonably low F. A 1.0 nm wide interference filter is used to block all but 4-5 peaks of the etalon. The light is then focused on GaAs photo multiplier detectors. Details of the design and performance are presented

Initial operation of the divertor Thompson scattering diagnostic on DIII-D

The first Thomson scattering measurements of n{sub e} and T{sub e} in the divertor region of a tokamak are reported. These data are used as input to boundary physics codes such as UEDGE and DEGAS and to benchmark the predictive capabilities of these codes. These measurements have also contributed to the characterization of tokamak disruptions. A Nd:YAG laser (20 Hz, 1 J, 15 ns, 1064 nm) is directed vertically through the lower divertor region of the DIII-D tokamak. A custom, aspherical collection lens (f /6.8) images the laser beam from 1-21 cm above the target plates into eight spatial channels with 1.5 cm vertical and 0.3 cm radial resolution. 2D mapping of the divertor region is achieved by sweeping the divertor X-point location radially through the fixed laser beam location. Fiber optics carry the light to polychromators whose interference filters have been optimized for low T{sub e} measurements. Silicon avalanche photo diodes measure both the scattered and plasma background light. Temperatures and densities are typically in the range of 5-200 eV and 1 - 10 x 10{sup 19} m{sup -3} respectively. Low temperatures, T{sub e} 8x10{sup 20} m{sup -3} have been observed in detached plasmas. Background light levels have not been a significant problem. Reduction of the laser stray light permits Rayleigh calibration. Because of access difficulties, no in-vessel vacuum alignment target could be used. Instead, an in situ laser alignment monitor provides alignment information for each laser pulse. Results are compared with Langmuir probe measurements where good agreement is found except for regions of high n{sub e} and low T{sub e} as measured by Thomson scattering

Physics of Turbulence Control and Transport Barrier Formation in DIII-D

This paper describes the physical mechanisms responsible for turbulence control and transport barrier formation on DIII-D as determined from a synthesis of results from different enhanced confinement regimes, including quantitative and qualitative comparisons to theory. A wide range of DIII-D data support the hypothesis that a single underlying physical mechanism, turbulence suppression via E x B shear flow is playing an essential, though not necessarily unique, role in reducing turbulence and transport in all of the following improved confinement regimes: H-mode, VH-mode, high-{ell}{sub i} modes, improved performance counter-injection L-mode discharges and high performance negative central shear (NCS) discharges. DIII-D data also indicate that synergistic effects are important in some cases, as in NCS discharges where negative magnetic shear also plays a role in transport barrier formation. This work indicates that in order to control turbulence and transport it is important to focus on understanding physical mechanisms, such as E x B shear, which can regulate and control entire classes of turbulent modes, and thus control transport. In the highest performance DIII-D discharges, NCS plasmas with a VH-mode like edge, turbulence is suppressed at all radii, resulting in neoclassical levels of ion transport over most of the plasma volume

Study of H-Mode Threshold Conditions in DIII-D

Studies have been conducted in DIII-D to determine the dependence of the power threshold P{sub lh} for the transition to the H-mode regime and the threshold P{sub hl} for the transition from H-mode to L-mode as functions of external parameters. There is a value of the line-averaged density n{sub e} at which P{sub lh} has a minimum and P{sub lh} tends to increase for lower and higher values of n{sub e}. Experiments conducted to separate the effect of the neutral density n{sub 0} from the plasma density n{sub e} give evidence of a strong coupling between n{sub 0} and n{sub e}. The separate effect of neutrals on the transition has not been determined. Coordinated experiments with JET made in the ITER shape show that P{sub lh} increases approximately as S{sup 0.5} where S is the plasma surface area. For these discharges, the power threshold in DIII-D was high by normal standards, thus suggesting that effects other than plasma size may have affected the experiment. Studies of H-L transitions have been initiated and hysteresis of order 40% has been observed. Studies have also been done of the dependence of the L-H transition on local edge parameters. Characterization of the edge within a few ms prior to the transition shows that the range of edge temperatures at which the transition has been observed is more restrictive than the range of densities at which it occurs. These results suggest that some temperature function is important for controlling the transition