Bulletin of the American Physical Society
2017 Annual Meeting of the Far West Section
Friday–Saturday, November 3–4, 2017; Merced, California
Session B3: Plasma Physics and Education |
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Chair: Alla Safronova, University of Nevada Reno Room: COB2 264 |
Friday, November 3, 2017 2:00PM - 2:12PM |
B3.00001: Teaching Experiences with a Large Class of Non-major Physics Students Mahendra Thapa In a classroom in California State University Chico (CSU CHICO), designed well for the flipped mode of teaching, approximately 95-100 non- physics majors were taught General Physics I during fall 2016 {\&} spring 2017. A number of students had not taken physics or math in high school. A balanced use of videos (obtained from textbook, experienced physics instructors, YouTube) were assigned for home use, and group discussions and lectures were used for the active learning environment in the class. In addition, several extra problem solving sessions were conducted. Students' performance was tested through three closed book exams, a final exam and quizzes. Mistakes seen in these tests and responses on extra homework will be presented. Student feedback on (i) homework (ii) tests (iii) teaching approaches (iv) textbook (v) use of electronics in the class and lab (vi) active participation during class (vii) grading schemes (viii) attendance policy and other burning issues like use of instructor's office hours will be shown. Shortcomings, identified through discussions with other faculty and active physics education researchers, will be presented as they will be addressed in future flipped classroom teaching. [Preview Abstract] |
Friday, November 3, 2017 2:12PM - 2:24PM |
B3.00002: Lawrence Livermore National Laboratory's EBIT-I Electron Beam Ion Trap: A host facility for interns Gregory Brown, Thusitha Arthanayaka, Peter Beiersdorfer, Natalie Hell, Tom Lockard, Edward Magee Lawrence Livermore National Laboratory's (LLNL) EBIT-I electron beam ion trap facility has been employed as a host to interns of many levels, including high school, undergraduate, and graduate students, as well as high school science teachers. While at LLNL's EBIT-I, interns are exposed to scientists from a diverse background involved in a variety of scientific fields, from high energy astrophysics, planetary physics and atomic physics, to the physics of burning plasmas and high-density laser plasmas. Interns are not only exposed to the daily lives of scientists at a national science facility, but also gain "hands on" experience by becoming active participants in one or more on-going experiments. An overview of the program will be presented. [Preview Abstract] |
Friday, November 3, 2017 2:24PM - 2:36PM |
B3.00003: Contributing towards Astrophysics and Physics Curriculum Enrichment through LLNL's Teacher Research Academy Tessie Lumabao The purpose of this presentation is to share my experience at the Lawrence Livermore National Laboratory's Teacher Research Academy. The academy provides opportunities for teachers to work with scientists in biotechnology, climate change, and astrophysics. As an astrophysics teacher intern, I worked with LLNL's EBIT (electron beam ion trap) scientists to help further resolve the Fe XVII emission problem by determining the polarization of lines 3C and 3D for Mo XXXIII and created a spectra for the lower transition energy levels of chromium. Through the internship, I gained experiences with equipment operation for EBIT-I and crystal spectrometers, observation and data collection for x-ray emissions, and software data analyzation. The collaboration between scientists also allowed me to contribute in scientific research to conclude that the polarization is not the solution towards the Fe XVII emission problem. These experiences and opportunities helped me to recognize how to enrich the physics curriculum in Hawaii, specifically at Waipahu High School, by teaching and engaging the students with modern scientific advancements. This work was performed under the auspices of the Department of Energy by LLNL under Contract No. DE-AC52-07NA27344. [Preview Abstract] |
Friday, November 3, 2017 2:36PM - 2:48PM |
B3.00004: Relative Intensities of the Resonance to Intercombination Transitions for Neonlike Ions. Dmytro Panchenko, Peter Beiersdorfer, Greg Brown, Natalie Hell, Vola Andrianarijaona $^{\mathrm{1}}$ We report the measured relative intensities of 1s$^{\mathrm{2}}$2s$^{\mathrm{2}}$2p$^{\mathrm{5}}_{\mathrm{1/2}}$3d$_{\mathrm{3/2}}$ $\to $ 1s$^{\mathrm{2}}$2s$^{\mathrm{2}}$2p$^{\mathrm{6}}$ resonance to 1s$^{\mathrm{2}}$ 2s$^{\mathrm{2}}$ 2p$^{\mathrm{5}}_{\mathrm{3/2}}$ 3d$_{\mathrm{5/2}} \quad \to $ 1s$^{\mathrm{2}}$2s$^{\mathrm{2}}$2p$^{\mathrm{6}}$ intercombination lines for Ne-like Kr$^{\mathrm{26+}}$ and Mo$^{\mathrm{32+}}$. The measurements were taken using the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory, also utilizing an x-ray microcalorimeter. The Mo$^{\mathrm{32+}}$ experiment, which is the highest-Z measurement of this type to date, displays a four-times closer agreement with theoretical predictions, as compared to previously conducted experiments of lower-Z ions. This hints at the narrowing of the disagreement between theory and experiments for increasing Z, not observed in the earlier data, and that the said disagreement may be confined to the range of atomic numbers where the correlation effects are strongest. $^{\mathrm{1}}$This work was performed under the auspices of the U.S. DoE by LLNL, contract DE-AC52-07NA27344, and was supported in part by NASA's APRA program and by the ESA, contract 4000114313/15/NL/CB. [Preview Abstract] |
Friday, November 3, 2017 2:48PM - 3:00PM |
B3.00005: Emission line spectra of Fe XI for astrophysical plasmas in the extreme ultraviolet region 60 - 140 {\AA}. Jaan Lepson, Peter Beiersdorfer, Gregory Brown, Duane Liedahl Accurate spectral catalogs are essential to analyze spectra of astrophysical plasmas observed by orbiting EUV and x-ray observatories, such as $Chandra,~XMM-Newton, ~Hinode$, and the $Solar ~Dynamics ~Observatory$. We report here on emission spectra of iron in the extreme ultraviolet recorded at an electron density of $\sim 5 \times 10^{11}$ cm$^{-3}$ at the Lawrence Livermore electron beam ion trap facility. In particular, we present measured spectra of Fe XI, covering the region 60 - 140 {\AA}. The spectra contain a large number of lines, which despite being rather weak compared to the stronger and better known lines above 170 {\AA}, can add up to significant flux. The measured spectra are compared to existing spectral data and newly calculated theoretical data. We use these calculations to tentatively identify the lines, most of which have not been identified before, and present measured and calculated wavelengths and line intensities. We use these measurements to identify new lines of Fe XI in the corona of Procyon, and reassign to Fe XI additional lines that had been previously attributed to other elements. We also find that the Fe XI emission contains multiple 4f -> 3d transitions that fall into one of the iron channels aboard the $SDO$ centered around 94 {\AA}. [Preview Abstract] |
Friday, November 3, 2017 3:00PM - 3:12PM |
B3.00006: Plasma sheath model in the presence of field-induced electron emission Jiba Dahal, Venkattraman Ayyaswamy Microplasma become the active area of research in the last decades because of its several applications in physics including nanomaterial synthesis, electronics, lighting, biomedicine, and metamaterials for controlling electromagnetic waves. More recently, field emission electrons from the field emission and their interaction with micro discharge due to high electric fields has shown to affect both pre and post breakdown. In this context, the current work focuses on the development of self-consistent sheath model. Microdischarges are driven by the field emission of electrons from the cathode which has been shown to play a role similar to secondary electron emission. This self-consistent sheath model using electric field and electron emission uniquely interplay between plasma and electrode to provide some insights into the current-voltage characteristics of microplasmas with an additional emission mechanism from the cathode. The results obtained from the model are evaluated and compare with PIC-MCC results [Preview Abstract] |
Friday, November 3, 2017 3:12PM - 3:24PM |
B3.00007: Verification and validation studies of continuum simulations of low-temperature plasmas Benjamin Marshall, Abhishek Kumar Verma, Ayyaswamy Venkattraman State-of-the-art microplasma devices have contributed to several challenges that require a fundamental understanding of the various mechanisms involved in order to achieve optimal operation for a given application. In this context, the role of computations cannot be stressed enough. Historically, the computational techniques used for simulating plasmas belong to two categories – continuum/fluid and kinetic methods. The primary goal of the current work is to report the exhaustive verification and validation studies performed using our in-house plasma solver implemented in the OpenFOAM framework. The continuum simulations presented here include continuity, conservation of momentum equations for both electron and ion species, an energy equation for electrons and the Poisson's equation for potential solution. The convergence characteristics of the continuum solver are presented for a range of pressures and excitation frequency (both direct current and high frequency operation are considered). The influence of the numerical schemes and models on the obtained solutions are also quantified. [Preview Abstract] |
Friday, November 3, 2017 3:24PM - 3:36PM |
B3.00008: X-ray Line Polarization of Mo X-pinch Radiation R.R. Childers, E.E. Petkov, A.A. Safronova, V.L. Kantsyrev, V.V. Shlyaptseva, I.K. Shrestha, M. Cooper, A. Stafford, K.A. Schultz, C.J. Butcher Polarization of x-ray radiation is a powerful tool in the study of atomic processes in astrophysical and high-energy-density (HED) plasmas, all of which can be effectively studied through pulse-powered laboratory plasmas. Furthermore, x-ray polarization can be a formidable diagnostic in the detection of non-Maxwellian, suprathermal electrons, which have been shown to induce linearly polarized spectral emission through collisional processes with ions. In this talk, we explore the polarization of Mo radiation from HED high-Z laboratory plasmas on the Zebra Generator at the UNR Nevada Terawatt Facility. We investigate the polarization of Mo (Z $=$ 42) plasma radiation through dual $\alpha $-quartz crystal (2d $=$ 6.67 {\AA}) spectropolarimetry with horizontal and vertical spatial resolution. In particular, polarization is evaluated through a comparative analysis of relative line intensities observed over a range of Ne-like Mo transitions. This is the first comprehensive study of x-ray line polarization in Mo HED plasmas. [Preview Abstract] |
Friday, November 3, 2017 3:36PM - 3:48PM |
B3.00009: Spectroscopy on tokamaks in support of x-ray astronomy P. Beiersdorfer, V. Soukhanovskii, E. Trabert, M. E. Weller, J. K. Lepson, M. L. Reinke Tokamaks operate in a density and temperature regime close to that of stellar coronae and in particular that of solar flares. Spectra recorded on tokamaks are, therefore, very similar to many astrophysical spectra and can be used for line identification and the calibration of spectral diagnostics essential for x-ray astronomy. We have installed a total of eight grating spectrometers on four US tokamaks to observe x-ray line emission in the range from 8 \AA\ to 450 \AA. Here we give some recent results, including the calibration of density-sensitive line ratios of iron on the NSTX-U spherical torus and line identifications in spectra of calcium from the Alcator C-mod tokamak. [Preview Abstract] |
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