Search NASA⌕ Search

Engineering topics

Wang, Yuming

Publications and source records attributed to Wang, Yuming.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Experimental study of the influence of gas puff locations on H-mode boundary plasmas with argon seeding on EAST

To investigate the optimal scenario of impurity seeding to obtain divertor plasma detachment for target protection, experiments with Ar&D 2 seeding from two different poloidal locations, the upper outer (UO) divertor target and lower outer (LO) target, were carried out on EAST. Partial energy detachment (the electron temperature near the strike point T e,spt ≤ 10 eV) were obtained with Ar&D 2 mixture puffing from the UO target and, for the first time, from the LO target into H-mode plasmas in the upper single null (USN) configuration. The peak heat flux q t on the UO target was significantly reduced (by ~80%). The rollover of ion flux density j s did not appear probably due to insufficient momentum loss, which is independent of the puff locations. The poloidal asymmetries of particle and heat fluxes on the targets have also been investigated. The UO-dominant asymmetry of particle flux was reversed, while the UO-dominant asymmetry of heat flux was mitigated but not reversed. The plasma confinement dropped by only 14% and 8.2% in the LO-puff case and UO-puff case, respectively, during detachment. The high level of C may contributed greatly to the higher radiation in the bulk plasma region and the greater decline in W MHD in the LO-puff case.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2016

Editorial: Reviewer Selection Process and New Areas of Expertise in GEMS

One method of selecting potential reviewers for papers submitted to the Journal of Geophysical Research Space Physics is to filter the user database within the Geophysical Electronic Manuscript System (GEMS) by areas of expertise. The list of these areas in GEMS can be self selected by users in their profile settings. The Editors have added 18 new entries to this list, an increase of 33 more than the previous 55 entries. All space physicists are strongly encouraged to update their profile settings in GEMS, especially their areas of expertise selections, and details of how to do this are provided.

Liemohn, Michael W.↗
NASA NTRS2016

Appreciation of the 2015 JGR Space Physics Peer Reviewers

The Editors of the Journal of Geophysical Research Space Physics are deeply indebted to the many people among the research community that serve this journal through peer review. The journal could not exist without the time and effort invested by the community through this voluntary activity, providing expert evaluations and thoughtful assessments of the work of others. In 2015, the journal had 1506 scientists contribute to the process with at least one peer review, for a total of 3575 reviews completed, including additional reviews of resubmitted manuscripts. There were 277 reviewers that contributed four or more reports in 2015. The average number of reviews per referee in 2015 was, therefore, 2.4. Note that the total number of manuscript final decisions (i.e., accept or reject) for Journal of Geophysical Research (JGR) Space Physics was 1147 in 2015. Of this, 774 were accepted and 373 were declined, for an acceptance rate of 67% last year. If the 1334 "revision" decisions are included in the tally, then the total number of decisions made in 2015 was 2481. Working out the arithmetic, it means that on average, a manuscript gets about 1.2 revision decisions before a final accept-or-reject decision. This explains the ~3.1 average number of reviews per manuscript throughout each paper's lifetime in the submission-revision editorial process. We are pleased and happy that the research community is willing and able to devote their resources toward this service endeavor. We appreciate each and every one of you that helped maintain the high quality of papers in JGR Space Physics last year. We look forward to another excellent year working with all of you through the year ahead.

Liemohn, Michael W.↗
NASA NTRS2016

Thermodynamic Spectrum of Solar Flares Based on SDO/EVE Observations: Techniques and First Results

The Solar Dynamics Observatory (SDO)/EUV Variability Experiment (EVE) provides rich information on the thermodynamic processes of solar activities, particularly on solar flares. Here, we develop a method to construct thermodynamic spectrum (TDS) charts based on the EVE spectral lines. This tool could potentially be useful for extreme ultraviolet (EUV) astronomy to learn about the eruptive activities on distant astronomical objects. Through several cases, we illustrate what we can learn from the TDS charts. Furthermore, we apply the TDS method to 74 flares equal to or greater than the M5.0 class, and reach the following statistical results. First, EUV peaks are always behind the soft X-ray (SXR) peaks and stronger flares tend to have faster cooling rates. There is a power-law correlation between the peak delay times and the cooling rates, suggesting a coherent cooling process of flares from SXR to EUV emissions. Second, there are two distinct temperature drift patterns, called Type I and Type II. For Type I flares, the enhanced emission drifts from high to low temperature like a quadrilateral, whereas for Type II flares the drift pattern looks like a triangle. Statistical analysis suggests that Type II flares are more impulsive than Type I flares. Third, for late-phase flares, the peak intensity ratio of the late phase to the main phase is roughly correlated with the flare class, and the flares with a strong late phase are all confined. We believe that the re-deposition of the energy carried by a flux rope, which unsuccessfully erupts out, into thermal emissions is responsible for the strong late phase found in a confined flare. Furthermore, we show the signatures of the flare thermodynamic process in the chromosphere and transition region in the TDS charts. These results provide new clues to advance our understanding of the thermodynamic processes of solar flares and associated solar eruptions, e.g., coronal mass ejections.

Wang, Yuming↗