Propagation of the phase of solar modulation

The phase of the 11 year galactic cosmic ray variation, due to a varying rate of emission of long lived propagating regions of enhanced scattering, travels faster than the scattering regions themselves. The radial speed of the 11 year phase in the quasi-steady, force field approximation is exactly twice the speed of the individual, episodic decreases. A time dependent, numerical solution for 1 GeV protons at 1 and 30 Au gives a phase speed which is 1.85 times the propagation speed of the individual decreases

Ion sputter textured graphite electrode plates

A specially textured surface of pyrolytic graphite exhibits extremely low yields of secondary electrons and reduced numbers of reflected primary electrons after impingement of high energy primary electrons. Electrode plates of this material are used in multistage depressed collectors. An ion flux having an energy between 500 iV and 1000 iV and a current density between 1.0 mA/sq cm and 6.0 mA/sq cm produces surface roughening or texturing which is in the form of needles or spires. Such textured surfaces are especially useful as anode collector plates in high tube devices

Ion sputter textured graphite

A specially textured surface of pyrolytic graphite exhibits extremely low yields of secondary electrons and reduced numbers of reflected primary electrons after impingement of high energy primary electrons. An ion flux having an energy between 500 eV and 1000 eV and a current density between 1.0 mA/sq cm and 6.0 mA/sq cm produces surface roughening or texturing which is in the form of needles or spines. Such textured surfaces are especially useful as anode collector plates in high efficiency electron tube devices

Flaw growth behavior in thick welded plates of 2219-T87 aluminum at room and cryogenic temperatures

Axial load fatigue and fracture tests were conducted on thick welded plates of 2219-T87 aluminum alloy to determine the tensile strength properties and the flaw growth behavior in electron beam, gas metal arc, and pulse current gas tungsten arc welds for plates 6.35 centimeters (2.5 in.) thick. The tests were conducted in room temperature air and in liquid nitrogen environments. Specimens were tested in both the as-welded and the aged after welding conditions. The experimental crack growth rate were correlated with theoretical crack growth rate predictions for semielliptical surface flaws

The 30/20 GHz flight experiment system, phase 2. Volume 2: Experiment system description

A detailed technical description of the 30/20 GHz flight experiment system is presented. The overall communication system is described with performance analyses, communication operations, and experiment plans. Hardware descriptions of the payload are given with the tradeoff studies that led to the final design. The spacecraft bus which carries the payload is discussed and its interface with the launch vehicle system is described. Finally, the hardwares and the operations of the terrestrial segment are presented

The 30/20 GHz flight experiment system, phase 2. Volume 1: Executive summary

Summary information on the final communication system design, communication payload, space vehicle, and development plan for the 30/20 GHz flight experiment will be installed on the LEASAT spacecraft which will be placed into orbit from the space shuttle cargo bay. The communication concept has two parts: a truck service and a customer premise service (CPS). The trucking system serves four spot beams which are interconnected in a satellite switched time division multiple access mode by an IF switch matrix. The CPS covers two large areas of the eastern United States with a pair of scanning beams

The 30/20 GHz flight experiment system, phase 2. Volume 3: Experiment system requirement document

An approach to the requirements document to be used to procure the system by NASA is presented. The basic approach is similar to the requirements document used in the commercial communication satellite. Enough detail requirements are given to define the system without tight constraints

ESO 3060170 -- a massive fossil galaxy group with a heated gas core?

We present a detailed study of the ESO 3060170 galaxy group combining Chandra, XMM and optical observations. The system is found to be a fossil galaxy group. The group X-ray emission is composed of a central dense cool core (10 kpc in radius) and an isothermal medium beyond the central 10 kpc. The region between 10 and 50 kpc (the cooling radius) has the same temperature as the gas from 50 kpc to 400 kpc although the gas cooling time between 10 and 50 kpc (2 - 6 Gyr) is shorter than the Hubble time. Thus, the ESO 3060170 group does not have a group-sized cooling core. We suggest that the group cooling core may have been heated by a central AGN outburst in the past and the small dense cool core is the truncated relic of a previous cooling core. The Chandra observations also reveal a variety of X-ray features in the central region, including a ``finger'', an edge-like feature and a small ``tail'', all aligned along a north-south axis, as are the galaxy light and group galaxy distribution. The proposed AGN outburst may cause gas ``sloshing'' around the center and produce these asymmetric features. The observed flat temperature profile to 1/3 R_vir is not consistent with the predicted temperature profile in recent numerical simulations. We compare the entropy profile of the ESO 3060170 group with those of three other groups and find a flatter relation than that predicted by simulations involving only shock heating, S $\propto$ r$^{~ 0.85}$. This is direct evidence for the importance of non-gravitational processes in group centers. We derive the mass profiles within 1/3 R_vir and find the ESO 3060170 group is the most massive fossil group known (1 - 2 X 10$^{14}$ M$_{\odot}$). The M/L ratio of the system, ~ 150 at 0.3 R_vir, is normal.Comment: 17 pages, 12 figures, to appear in ApJ. A high-resolution version can be downloaded from http://cxc.harvard.edu/~msun/esoa.p

The survival and destruction of X-ray coronae of early-type galaxies in the rich cluster environments: a case study of Abell 1367

A new Chandra observation of the northwest region of the galaxy cluster A1367 reveals four cool galaxy coronae (0.4 - 1.0 keV) embedded in the hot intracluster medium (ICM) (5 - 6 keV). While the large coronae of NGC 3842 and NGC 3837 appear symmetric and relaxed, the galaxy coronae of the \lsim L* galaxies (NGC 3841 and CGCG 97090) are disturbed and being stripped. Massive galaxies, with dense cooling cores, are better able to resist ram pressure stripping and survive in rich environments than \lsim L* galaxies whose galactic coronae are much less dense. The survival of these cool coronae implies that thermal conduction from the hot surrounding ICM has to be suppressed by a factor of at least 60, at the corona boundary. Within the galaxy coronae of NGC 3842 and NGC 3837, stellar mass loss or heat conduction with the Spitzer value may be sufficient to balance radiative cooling. Energy deposition at the ends of collimated jets may heat the outer coronae, but allow the survival of a small, dense gas core (e.g., NGC 3842 in A1367 and NGC 4874 in Coma). The survived X-ray coronae become significantly smaller and fainter with the increasing ambient pressure.Comment: 11 pages, 7 figures, emulateapj5, accepted by Ap

Images, structural properties and metal abundances of galaxy clusters observed with Chandra ACIS-I at 0.1<z<1.3

We have assembled a sample of 115 galaxy clusters at 0.1<z<1.3 with archived Chandra ACIS-I observations. We present X-ray images of the clusters and make available region files containing contours of the smoothed X-ray emission. The structural properties of the clusters were investigated and we found a significant absence of relaxed clusters (as determined by centroid shift measurements) at z>0.5. The slope of the surface brightness profiles at large radii were steeper on average by 15% than the slope obtained by fitting a simple beta-model to the emission. This slope was also found to be correlated with cluster temperature, with some indication that the correlation is weaker for the clusters at z>0.5. We measured the mean metal abundance of the cluster gas as a function of redshift and found significant evolution, with the abundances dropping by 50% between z=0.1 and z~1. This evolution was still present (although less significant) when the cluster cores were excluded from the abundance measurements, indicating that the evolution is not solely due to the disappearance of relaxed, cool core clusters (which are known to have enhanced core metal abundances) from the population at z>0.5.Comment: 23 pages, 12 figures. Accepted for publication in ApJS. Updated to match published version. Redshifts of two clusters (RXJ1701 and CL0848) corrected and two observations of MACSJ0744.8 have been combined into one. Conclusions unchanged. A version with images of all of the clusters is available at http://hea-www.harvard.edu/~bmaughan/clusters.htm