Swirl-can combustor segment

Combustor produces uniform circumferential and radial combustor exit temperature profiles and high combustion efficiency at high temperature loads. Absence of diluent air entry ports eliminates stress concentration points, low pressure fuel alleviates nozzle fouling, and abundant air at all burning stages reduces smoke

Digital filter synthesis computer program

Digital filter synthesis computer program expresses any continuous function of a complex variable in approximate form as a computational algorithm or difference equation. Once the difference equation has been developed, digital filtering can be performed by the program on any input data list

An investigation of small-scale motions and the forecasting of wind profiles over short periods of time at Cape Kennedy, Florida

Small scale motions and numerical wind profiles forecasting for short periods at Cape Kenned

Letter

The onset of type I edge localized modes (ELMs) is investigated on the DIII-D tokamak. A fast imaging camera is used with an integration time of 1 νs and a time between frames of about 15 νs continuously recording for a period of 1.3 s. It is observed that type I ELMs onset starts with a precursor oscillation at the mid-plane caused by a toroidally rotating localized structure with a spatial scale increasing with time. This is confirmed by the toroidal set of magnetic probes and continues until the filamentary structure(s) strongly interacts with the first wall at the outer mid-plane. This triggers a strong plasma-wall interaction that later spreads to affect the whole scrape-off layer. The properties of the observed localized structure(s) are in good agreement with the ballooning finger structure occurring in the early non-linear phase of the peeling-ballooning instability. © 2009 IAEA, Vienna.Wakatani M, 1999, NUCL FUSION, V39, P2175, DOI 10.1088-0029-5515-39-12-302; Antar GY, 2006, PHYS PLASMAS, V13, DOI 10.1063-1.2198210; Becoulet M, 2003, PLASMA PHYS CONTR F, V45, pA93, DOI 10.1088-0741-3335-45-12A-007; Coda S, 2001, NUCL FUSION, V41, P1885, DOI 10.1088-0029-5515-41-12-316; Cowley S, 1996, PHYS PLASMAS, V3, P1848, DOI 10.1063-1.871980; Cowley SC, 2003, PLASMA PHYS CONTR F, V45, pA31, DOI 10.1088-0741-3335-45-12A-003; Eich T, 2005, PLASMA PHYS CONTR F, V47, P815, DOI 10.1088-0741-3335-47-6-007; Hill DN, 1997, J NUCL MATER, V241, P182, DOI 10.1016-S0022-3115(97)80039-6; Kirk A, 2005, PLASMA PHYS CONTR F, V47, P315, DOI 10.1088-0741-3335-47-2-008; Kirk A, 2005, PLASMA PHYS CONTR F, V47, P995, DOI 10.1088-0741-3335-47-7-003; Leonard AW, 2003, PHYS PLASMAS, V10, P1765, DOI 10.1063-1.1567723; Snyder PB, 2005, PHYS PLASMAS, V12, DOI 10.1063-1.1873792; Solomon WM, 2004, REV SCI INSTRUM, V75, P3481, DOI 10.1063-1.1790042; Wade MR, 2005, PHYS REV LETT, V94, DOI 10.1103-PhysRevLett.94.225001; Zohm H, 1996, PLASMA PHYS CONTR F, V38, P1213, DOI 10.1088-0741-3335-38-8-01234

Ablative response of a silica phenolic to simulated liquid propellant rocket engine operating conditions

Ablative response of silica phenolic to simulated liquid propellant rocket engine operating condition

Ultrafast magnetophotoconductivity of semi-insulating gallium arsenide

The speed of opto-electronic switches is increased or decreased by the application of a magnetic field. This is achieved by inducing a carrier drift toward or away from the semiconductor surface, resulting in the enhancement or suppression of surface recombination. We establish that surface recombination plays a major role in determining the speed of the opto-electronic switch

Interpretation of runaway electron synchrotron and bremsstrahlung images

The crescent spot shape observed in DIII-D runaway electron synchrotron radiation images is shown to result from the high degree of anisotropy in the emitted radiation, the finite spectral range of the camera and the distribution of runaways. The finite spectral camera range is found to be particularly important, as the radiation from the high-field side can be stronger by a factor $10^6$ than the radiation from the low-field side in DIII-D. By combining a kinetic model of the runaway dynamics with a synthetic synchrotron diagnostic we see that physical processes not described by the kinetic model (such as radial transport) are likely to be limiting the energy of the runaways. We show that a population of runaways with lower dominant energies and larger pitch-angles than those predicted by the kinetic model provide a better match to the synchrotron measurements. Using a new synthetic bremsstrahlung diagnostic we also simulate the view of the Gamma Ray Imager (GRI) diagnostic used at DIII-D to resolve the spatial distribution of runaway-generated bremsstrahlung.Comment: 21 pages, 11 figure

Control of large space structures

The control of large space structures was studied to determine what, if any, limitations are imposed on the size of spacecraft which may be controlled using current control system design technology. Using a typical structure in the 35 to 70 meter size category, a control system design that used actuators that are currently available was designed. The amount of control power required to maintain the vehicle in a stabilized gravity gradient pointing orientation that also damped various structural motions was determined. The moment of inertia and mass properties of this structure were varied to verify that stability and performance were maintained. The study concludes that the structure's size is required to change by at least a factor of two before any stability problems arise. The stability margin that is lost is due to the scaling of the gravity gradient torques (the rigid body control) and as such can easily be corrected by changing the control gains associated with the rigid body control. A secondary conclusion from the study is that the control design that accommodates the structural motions (to damp them) is a little more sensitive than the design that works on attitude control of the rigid body only