1.6° ANNUAL October 1, 1991 to REPORT September 30,1992 PRINCETON PLASMA PHYSICS LABORATORY ••-•'• «*^X*„ jf. ..>„, '» OOO.-'MfJv,' PPPL - Q - 50 Computer simulation of turbulence in a tokamak plasma. Visualization of the density fluctuations from an ion-temperature gradient-driven instability before the onset of turbulence. The colors represent different values of changes in the density. These results were generated using a three- dimensional toroidal gyrokinetic simulation using one million particles. The simulation was run on a massively parallel supercomputer. Graphic: S.E. Parker and W.W. Lee Cover Design: Joseph Belica Funding for the color cover was provided by nonappropriated funds. No Department of Energy funds were used. Annual Report Covering the Period October 1,1991 to September 30,1992 Princeton University Plasma Physics Laboratory Princeton, New Jersey 08543 PPPL-Q-50 Unless otherwise designated, the work in this report is funded by the United States Department of Energy under contract DE-AC02-76-CHO-3073. Printed in the United States of America MASIER & D!GTr*au\,?Oix OF Thli* DOCUMENT « UNLiMntD Contents Preface i Principal Parameters Achieved in Experimental Devices for Fiscal Year 1992 v Tokamak Fusion Test Reactor 1 Princeton Beta Experiment-Modification 51 Current Drive Experiment-Upgrade 65 Tokamak Physics Experiment/Steady-State Advanced Tokamak 71 International Thermonuclear Experimental Reactor 79 International Collaboration 87 X-Ray Laser Studies 93 Plasma Processing: Deposition and Etching of Thin Films 101 Pure Electron Plasma Experiments 107 Theoretical Studies 111 Tokamak Modeling 121 High-Field Magnet Project 125 Engineering Department 127 Environment, Safety, and Health and Quality Assurance 139 Technology Transfer 149 Office of Human Resources and Administration 153 PPPL Invention Disclosures for Fiscal Year 1992 159 Office of Resource Management 163 Graduate Education: Plasma Physics 169 Graduate Education: Program in Plasma Science and Technology 173 Science Education Program 177 Section Coordinators 179 Princeton Plasma Physics Laboratory Reports for Fiscal Year 1992 181 Glossary of Abbreviations, Acronyms, Symbols 189 Preface The Tokamak Fusion Test Reactor (TPTR) continue transport and advanced-tokamak-orieuted made significant experimental progress in a number studies with the objective of completing TFTR's D- of important areas during a relatively brief 1991/ D contributions to the Transport Initiative. The 92 experimental period. Improved wall-conditioning parameters achievable in the TFTR supershot techniques and new ion cyclotron range of frequency regime have been extended to electron temperature (ICRF) limiters produced enhanced supershot per­ Te(0) < 12 keV, ion temperature Tj(0) < 35 keV, with formance in large (R = 2.6 m) plasmas, allowing a peak D-D fusion reactivity corresponding to about the favorable confinement regime to be extended 5.6 x 1016 neutrons/second. The advanced tokamak, to plasma currents of Ip = 2 MA and beam power P[, high beta-poloidal regime in TFTR has been = 30 MW and yielding new record neutron product extended to Troyon coefficients of about 4.5 and rates (4 x 1016 neutrons/second) at this major energy confinement times up to 3.5 times the L- radius. With two additional ICRF antennas, the mode value; a substantial fraction of the plasma coupling of high-power ICRF to these plasmas cross section in these cases is in the second stability should be favorable. Indeed, the coupling of 7 MW regime for ballooning modes. of ICRF power was already achieved with the two Four different fluctuation diagnostics are now antennas presently installed. operational on TFTR. Results from microwave re- The TFTR also continues to make major con­ flectometry and beam-emission spectrometry (BES) tributions to the study of plasma transport in high- continue to indicate relatively long (2-3 cm) radial temperature tokamaks, directed especially at correlation lengths; the poloidal wave-number understanding the differences between the low- spectrum is dominated also by quite long wave­ confinement mode (L-mode) and supershot regimes. lengths (=6 cm). The BES diagnostic has been able An important result has been to use density and to provide a revealing statistical visualization of current profile control to achieve confinement en­ turbulence in TFTR over a substantial fraction of hancement factors up to 3.5 over the L-rnode. the radius. The motional Stark effect diagnostic has An objective of the 1991/92 experimental run been brought into operation; for a high beta-poloidal was to test the helium and oxygen glow cleaning TFTR plasma discharge, the q(r)-profile is found to technique, which is planned to be used in the evolve in a way that raises q(0) somewhat above deuterium-tritium (D-T) phase to remove tritium unity—an encouraging result in the context of trapped in layers of eroded and redeposited carbon. advanced-tokamak concepts. New direct measure­ A three-month outage followed the 1991/92 exper­ ments of escaping fast-ion flux further confirm the imental period for the purpose of installing two identification of fluctuations seen at low toroidal additional ICRF antennas, to allow up to 12.5 MW field values as toroidal Alfven eigenmodes (TAE of coupled power, and for installing D-T diagnostics, modes) excited by beam ions; there is also clear the tritium pellet injector, and auxiliary tritium correlation between the neutron rate and the equipment. magnetic fluctuations when these modes are Experimental operations resumed in May, 1992. present. The ion cyclotron heating power in TFTR The goals for the run were: (i) to develop deuterium- has reached 11.4 MW, essentially its design value. deuterium (D-D) operating regimes for higher pro­ With H-minority ion cyclotron heating at relatively jected values of Qr/p and for more intense popu­ low ICRF power, TAE-like activity has been lations of alpha particles, especially higher alpha- observed, apparently excited by ICRF-energized particle contributions to the plasma beta value; (ii) minority ions as predicted by theory. to develop specific experimental run sequences to Preparations for D-T operation are underway. be employed in the D-T experiments; and (iii) to Activities are well advanced in relation to the Princeton Plasma Physics Laboratory Fiscal Year 1992 Annual Report I Preface tritium handling systems, heating systems (i.e., options. The Fusion Energy Advisory Committee tritium beams), D-T diagnostics (neutron "hard­ (FEAC), as well as a National Task Force formed ening" of existing diagnostics and new alpha- to oversee the activities of the advocate groups and particle and thermal helium diagnostics), and core team, expressed a strong preference for the environmental, safety, and health compliance. The SSAT concept, given program needs for advanced tritium systems are now operational in deuterium tokamak studies and the constraint of approx­ and the neutral-beam D-T operating scenario has imately $500M capital cost (Total Project Cost, fiscal been demonstrated using deuterium and helium-4. year 1992 dollars). Installation of supplementary shielding on one Test The TPX design effort has now been successfully Cell wall allows up to 1021 deuterium-tritium launched as a national project with a project team neutrons per year, corresponding to about 1,000 drawn broadly from United States fusion labora­ total D-T plasma shots, including about 100 high- tories. The Laboratory is advised on all aspects of power shots, during the planned 1993/94 ex­ the TPX Project by a National TPX Council, and perimental period. The TFTR Environmental the TPX Project is advised on technical require­ Assessment was approved by the U.S. Department ments by a Program Advisory Committee. The of Energy and the New Jersey Department of overall programmatic mission of the TPX is to de­ Environmental Protection and Energy, and its monstrate (i) the physics and technology needed to "finding of no significant impact" has been discussed extend tokamak operation into the steady-state with the local community. A supplemental analysis regime and (ii) advances in fundamental tokamak to the Environmental Assessment has resulted in performance parameters on time scales long approval for increasing the in-vessel tritium limit compared with current-relaxation and plasma-wall to 20,000 Curies. equilibration times. Favorable results from TPX are The TFTR program now involves collaborations essential to further development of an attractive with over thirty universities, laboratories, and steady-state advanced-tokamak fusion reactor. industries, including several foreign institutions. The modified Princeton Beta Experiment (PBX- Major university collaborators include Columbia M) resumed experimental operations early in FY92. University, Massachusetts Institute of Technology, The PBX-M program is aimed at the exploration of University of California at Irvine, University of advanced techniques for entry into the "second Illinois, University of Texas, and University of stability regime," using strong magnetic shaping Wisconsin; laboratories with substantial involve­ of the plasma cross section, together with radio- ment in the TFTR program include Oak Ridge frequency heating and current drive to tailor the National Laboratory, Los Alamos National Lab­ plasma pressure and current profiles. The PBX-M oratory, Sandia National Laboratories (Albu­ is now equipped with 1MW of lower-hybrid current querque and Livermore), Idaho National En­ drive (LHCD) and 2 MW of ion-Bernstein-wave