CONF-811087 DE82 019828 Proceedings of the Fourth Symposium on the Physics and Technology of Compact Toroids Held at Lawrence Livermore National Laboratory October 27-29, 1981 R. F. Post W. C. Turner Editors Lawrence Livermore National Laboratory Manuscript Date: June 11, 1982 LAWRENCE LIVERMORE LABORATORY University of California • Livermore, California • 94550 PROGRAM - 1 REVIEW OF SYMPOSIUM - 3 POSTER SESSIONS - 9 SYMPOSIUM PAPERS - 13 I. Field Reversed Theta Pinch-Theory - 13 II. Field Reversed Theta Pinch Experiment - 55 III. Spheromak - Theory - 73 IV. Spheromak - Experiment - 123 V. General - 169 CONFERENCE ATTENDEES - 249 Hosted by the Lawrence Livermore National Laboratory, the Fourth Symposium on the Physics and Technology of Compact Toroids took place on the 27-29 October 1981. Attendees, numbering 80, heard 10 review papers in three morning plenary sessions, and interacted in two afternoon poster sessions where some 45 contributions were presented. There were 7 participants from overseas, including 6 scientists from Japan, and 1 from West Germany. Immediately following the Symposium, a two-day Joint U.S./Japan workshop on compact toroid research was held. The review papers covered mainline approaches to compact torus research—the field-reversed theta pinch and the spheromak configuration—along with related fields (e.g. the reversed-field Z pinch) and common concerns such as particle transport, beam applications, and impurity radiation. Progress in understanding tilting/shifting instabilities, gross MHD stability, and transport scalings was highlighted. Authors: D. V. Anderson, J. H. Hammer, D. C. Barnes (LLNL & Univ. of Texas). Investigates methods for numerically extending analytical solutions of field-reversed theta pinch equilibria for stability and dynamic studies using SEECOD and CYLEQ codes. Author: John Brandenburg (LLNL). Proposes a 'Sonic Bath' model where closed field line plasma forms an unstable intermediate equilibrium after axial contraction and relaxes to a state of minimum magnetic energy through shear Alfvén turbulence. Author: Douglas S. Harned (UC Berkeley / LANL). Uses the AQUARIUS quasineutral hybrid simulation code to show that m = 2 rotational instabilities can occur for ion rotation levels well below thresholds predicted by previous finite Larmor radius (FLR) theory. Authors: K. F. McKenna, D. J. Rej, M. Tuszewski (LANL). Analytically investigates quasi-static formation of FRC plasmas under constraints of radial equilibrium and energy losses, including rotating-magnetic-field (RMF) current drive techniques. Authors: R. W. Moses, D. W. Hewett (LANL). Discusses nonadiabatic collisionless processes occurring at a spindle cusp that transfer ions and electrons across a separatrix. Authors: J. L. Schwarzmeier, C. E. Seyler, D. C. Barnes (LANL, Cornell, Univ. of Texas). Employs the Vlasov-fluid dispersion functional to evaluate finite Larmor radius and equilibrium profile effects on the internal tilt mode stability. Authors: A. G. Sgro, R. L. Spencer, C. Lilliequist (LANL). Simulates post-formation resistive-timescale evolution of compact toroids using a 1-1/2 D transport code with singular geometry handling at the separatrix. Authors: Ross L. Spencer, Dennis W. Hewett (LANL). Solves the Grad-Shafranov equation for a step-function current profile in an infinitely long flux-conserving cylinder, finding up to four solutions including elongated racetrack equilibria near a bifurcation point. Authors: Loren C. Steinhauer, Richard D. Milroy, Alan L. Hoffman (Mathematical Sciences Northwest, Inc.). Develops quasi-steady and time-dependent 1-D/2-D models to explain particle and poloidal flux loss rates observed in FRX-B and TRX-1 experiments. Authors: M. Tuszewski, R. K. Linford, J. Lipson, A. G. Sgro (LANL). Presents steady-state 1-D particle transport models based on lower-hybrid-drift (LHD) turbulence saturation mechanisms, comparing scaling laws (R^2/rho_i0) with FRX-B experimental data. Authors: W. T. Armstrong et al. (LANL). Reports preliminary operation of the FRX-C large theta-pinch facility (45 cm diameter, 2 m length), demonstrating stable lifetimes of 70-100 microseconds with densities ~ 4 x 10^15 cm^-3. Authors: Alan L. Hoffman, W. T. Armstrong (MSNW). Demonstrates triggered reconnection and octopole barrier field techniques in the TRX-1 device to optimize flux trapping efficiency and plasma heating. Authors: Y. Nogi et al. (Nihon Univ., Nagoya Univ., Osaka Univ.). Investigates onset times and scaling laws of the n = 2 rotational instability across NUCTE, STP-L, and PIACE experiments in Japan. Authors: E. Sevillano, F. L. Ribe, H. Meuth (Univ. of Washington). Studies spontaneous and delayed magnetic field reconnection and plasma confinement in the High Beta Q Machine (HBQM). Author: Steven P. Auerbach (LLNL). Formulates an analytical model showing that impurity radiation (predominantly oxygen and carbon) explains finite lifetimes, linear current decay, and density insensitivity in coaxial-gun spheromak experiments. Author: John Brandenburg (LLNL). Generalizes Taylor's minimum energy relaxation theory by introducing the 'Laminativity' invariant to include finite-beta effects in compact tori and reversed-field pinches. Authors: Eliezer Hameiri, Harvey A. Rose (Courant Institute & LANL). Constructs a nonlinear statistical mechanics model of compressible magnetohydrodynamic fluctuations using discrete lattice-Fourier conservation variables and Gibbs distribution ensembles. Authors: James H. Hammer, Charles W. Hartman (LLNL). Explores injecting magnetized compact toroids into tokamaks and other toroidal devices to supply magnetic helicity for steady-state current drive, heating, and fueling. Authors: Charles W. Hartman, James H. Hammer (LLNL). Proposes accelerating magnetically confined plasma rings in coaxial electrode structures or magnetic gradients up to 10 MJ kinetic energy for ICF drivers, fusion reactor fueling, and nuclear synthesis. Authors: M. Katsurai, K. Katayama, T. Sato (Univ. of Tokyo & Hiroshima Univ.). Examines merging of two spheromaks via 2-D MHD simulations, observing that toroidal flux is doubled while poloidal flux is conserved, discussing implications for steady-state reactor designs. Authors: A. I. Shestakov, N. J. O'Neill (LLNL). Employs the RIPPLE VI linear resistive stability code to analyze n = 1 tilt and shift modes across five prolate-to-oblate spheromak equilibrium configurations. Authors: D. E. Shumaker, B. McNamara, W. C. Turner (LLNL). Uses the 1-1/2 D transport code FRT to model neutral beam injection (4 MW at 12 keV) into magnetized coaxial gun-formed compact toroids, studying beta limits and thermal transport. Authors: Y. C. Sun, S. C. Jardin, D. Heifetz, M. Yamada, D. E. Post (PPPL). Models spheromak formation and energy loss in Proto S-1C including 2-D resistive MHD, coronal non-equilibrium impurity radiation (C and O), and Monte Carlo neutral charge exchange/ionization. Authors: Cris W. Barnes et al. (LANL). Reports on hydrogen glow discharge cleaning in the CTX coaxial gun spheromak facility, achieving lifetime extension up to 550 microseconds and dramatic reduction in carbon radiation. Authors: H. Bruhns et al. (Univ. of Maryland). Evaluates stainless steel liners, elkonite/carbon electrodes, and Figure-8 passive stabilization coils for tilt and shift mode control in the PS-1 spheromak. Authors: H. W. Hoida et al. (LANL). Details measurements of magnetic configuration lifetimes, snipper coil reconnection, and pyroelectric bolometer radiation power in CTX spheromaks. Authors: A. Janos et al. (PPPL). Describes experimental results from Proto S-1C (R = 12 cm, a = 6-8 cm, I_p = 60 kA) utilizing inductive flux-core formation, analyzing MHD stability and impurity radiation barriers. Authors: K. Kawai, Z. A. Pietrzyk (Univ. of Washington). Demonstrates generation and translation of spheromak plasmoids with embedded toroidal fields generated from a conical theta-pinch discharge into an aluminum flux conserver. Authors: S. O. Knox, B. L. Wright (LANL). Outlines designs for low-frequency and fast magnetosonic / shear Alfvén wave RF heating systems (0.1-10 MHz) in CTX using equatorial antenna straps. Authors: C. Munson et al. (PPPL); R. F. Post, W. C. Turner (LLNL). Investigates experimental tilt stabilization via Figure-8 coils in Proto S-1 A/B and proposes titanium-hydride coated electrodes to desorb pure hydrogen during gun discharge to mitigate impurity influx. Authors: W. C. Turner et al. (LLNL). Analyzes magnetic helicity efficiency (K_p/K_in ~ 0.5), pyroelectric radiation measurements, and density scaling with gas puffing and discharge cleaning in Beta II. Authors: K. Watanabe et al. (Osaka Univ.). Examines successive injection and merging of two CT plasmas in an oblate flux conserver, finding doubled toroidal flux and slow interior field reconnection over 100 microseconds. Contains presentations on: Traveling Mirror Adiabatic Compressors (P. M. Bellan); Analytic Field-Reversed Mirror Equilibria (J. K. Boyd); Relativistic Electron Beam (REB) ring studies at Nagoya University (M. Hasegawa et al.); Review of Anomalous Diffusion in Toroidal Plasma (N. A. Krall); MeV/GeV Ion Layers for Fusion (J. R. McNally, Jr.); Intense Ion Beam Propagation (S. Robertson et al.); Microsecond Rotating REB Generation (G. Saenz); Prototype Moving-Ring Reactor Design (A. C. Smith, Jr. et al.); and a Comprehensive Review of Japanese Compact Torus Research (K. Watanabe).