Edward W. Thomas

Professor Emeritus

Education

Research

Current research activities are divided between studies of educational matters related to Physics service courses, SIMS analysis of materials and the understanding of secondary ion emission and also prediction of fusion plasma operation characteristics.

Like most other major universities Ga. Tech's School of Physics provides Introductory Physics as a service course to non-majors; in our case mainly to engineers. My objective is to improve the performance of students in these classes, then understand why students have difficulty with the material and to predict those students at risk of failure so that interventions may be designed to improve their performance. Working with Cognitive Psychologists and with staff of student service units we have devised ways of improving performance in these classes by 10 to 20% and thereby halving the rate at which students fail to attain satisfactory grades. Focus has been on the "homework" performed by students since it is here that they engage most actively with the material. Standard text book problems are not challenging for the better student and do not provide the necessary routine training that the weaker students needs to develop confidence. For the latter situation we have devised a technique known as "Precision Teaching" which provides a set of simple exercises performed against the clock and repeated till mastery is demonstrated. The intent here is to develop a high degree of "automatic" (and correct !) responding to simple manipulations. A further approach is to provide somewhat complex problems which cannot be answered by use of text-book formulae and which require the student to revisit and to understand the underlying materials. We have also shown that the students performance in Introductory Physics courses can be predicted from their records. We find that we can predict with a 76% reliability, whether or not a student will attain a satisfactory grade or an unsatisfactory grade. The most important predictive parameters are the student's immediate past performance in related courses; specifically their overall GPA, grade in preceding Math courses and grade in any preceding Physics course. The prediction technique is known as Discriminant Analysis and is particularly designed for handling parameters which are discreet (such as letter grades in courses).

Research in Secondary Ion Mass Spectroscopy (SIMS) is performed using a commercial SIMS analysis machine from ATOMIKA of Germany. The equipment is located in the Microelectronics Center and is mainly devoted to their needs. The application of these systems is to the analysis of materials depth distributions. The technique is to sputter etch the surface and mass spectroscopically analyze the ejected ions. Following an ion signal as a function of time (and therefore sputter etching) one can develop a profile of that constituency's distribution with depth. The technique is particularly used for study of superlattice structures and other microelectronic configurations. I operate the machine in support of other groups which require materials to be analyzed and generally try to train their students to do the work. Most of the demand comes from MBE materials growth groups and from the Photovoltaic cell Development Center. I am personally interested in the study of the mechanism by which the ejected ions are created. Only a small faction of the ejected atoms are in the ionized state and there are no successful techniques for predicting that fraction. Undoubtedly the ionization rate is related to the details of the potential function between emerging atom and surface and to its evolution as a function of time during the atom's exit from the surface. I am particularly interested in the formation of ejected molecular species particularly CsX+ ions, ejected by incident Cs+ beams. These species are generally not created in gas phase ions sources and their structure is virtually unknown. We have, with others, shown that monitoring these species is a particularly good way of making absolute measurements of X concentration in the target.

In association with Bill Stacey of Nuclear Engineering I do some work on the prediction of fusion plasma behavior in the near limiter region. I am particularly interested in identifying which process influence the core temperature and whether or not the existing data on such processes are of sufficient accuracy for redictive purposes. In a sense this is a study of the sensitivity of the plasma operation to the details of the Atomic Physics which occurs at its edge. We have recently shown that, in the recycling of fuel from the limiter, it makes little difference to the temperature of the device whether molecular species are excited or in the ground state. 

Positions Held

• Assistant Research Physicist, EES, Ga.Tech 1964-1965
• Assistant Professor, Ga. Tech 1965-1967
• Associate Professor Ga. Tech 1967-1973
• Professor of Physics, Ga. Tech 1973-present
• Director (Chair) School of Physics, Ga. Tech. 1982-1991
• Secretary of the Faculty 1998-present

Short Term Positions and Consultancies

• Visiting Scientist and Sputtering Group Leader, FOM Institute for Atomic and Molecular Physics, Amsterdam 1971-1972
• Research Associate, Culham Laboratory of the UK AEA, 1978-79
• Visiting Scientist, Forskingsinstitutet fur Atomfysik, Stockholm, 1981-1982
• Visiting Consultant, IAEA Vienna 1981, 1989, 1990, 1991
• Visiting Scientist, Imperial College London 1992
• Visiting Scientist, Open University, UK 1996
• Consultant to Lester Labs 1976
• Consultant to Unitron International 1976
• Consultant to Rollins Inc 1977
• Consultant to Oak Ridge Laboratories (as off-site employee of data center) 1965 to present.

Other Publications

1. M. J. Marr , E. W. Thomas and others. "Development of Instructional systems for Teaching an Electricity and Magnetism course for Engineers". Am. J. Phys. 67, 789 (1999).
2. E. W. Thomas and R. J. Hume. "Relationship of Homework complexity to quiz Scores" Frontiers in Education 1997. IEEE Publication # 97CH36099 (page # T3G.1).
3. E. W. Thomas, and others. "Using Discriminant analysis to Identify Students at risk". Frontiers in Education 1996. IEEE Publication 96CH35946 (page # 6b6.2)
4. E. W. Thomas and W. M. Stacey "Atomic and Molecular Deuterium Cross Section Uncertainties and Molecular Recycling Effects in the Divertor Region of Tokamaks". Physics of Plasmas 4, 678 (1997)
5. W. M. Stacey E. W. Thomas and T. M. Evans. "Data and Extended Diffusion Theories for Neutral Particle Transport in tokamak Divertors". Physics of Plasmas 2, 3740 (1995).
6. Y. Kim, A. Erbil, E. W. Thomas and other. "Study of thin film Ferroelectric Supperlattices". Mat. Res. Soc,. Symp. Proc Vol 433, 339 (1996)
7. H.C.Chou, A. Rohatgi, E. W. Thomas and Others. "Copper Migration in CdTe Hetrojunction solar Cells". J. Electron Matl. 25, 1059 (1996)