14 Matching Results

Search Results

Results: 1 - 14
open access

Transport, stability and relaxation of a spheromak

Description: We consider a zero-..beta.. spheromak contained in a rectangular region having perfectly conducting boundaries in its minimum energy state, and we calculate its evolution. Our results may be summarized as follows. Since this state is a stable equilibrium, the initial evolution of the plasma is caused by diffusion. We simulate this using a transport code. We find that q at the magnetic axis drops and q(r) becomes flat. When q on axis drops below 0.5, the spheromak becomes unstable to an n = 2 ki… more
Date: January 1, 1984
Creator: Sgro, A. G.; Marklin, G. & Mirin, A. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Global energy confinement scaling for neutral-beam-heated tokamaks

Description: A total of 677 representative discharges from seven neutral-beam-heated tokamaks has been used to study the parametric scaling of global energy confinement time. Contributions to this data base were from ASDEX, DITE, D-III, ISX-B, PDX, PLT, and TFR, and were taken from results of gettered, L-mode type discharges. Assuming a power law dependence of tau/sub E/ on discharge parameters kappa, I/sub p/, B/sub t/, anti n/sub e/ P/sub tot/, a, and R/a, standard multiple linear regression techniques we… more
Date: October 1, 1984
Creator: Kaye, S.M. & Goldston, R.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Accelerator-based plasma-wall interaction studies on the TEXTOR tokamak

Description: Deposition probes are commonly used to determine plasma edge characteristics in tokamaks. Such probes are frequently analyzed using accelerator-based techniques and can yield information on impurity fluxes, hydrogen fluxes and energies, and surface erosion rates in the plasma edge. Several types of deposition probes have been employed to investigate the plasma edge region of the TEXTOR tokamak in Juelich, FRG. TEXTOR is a moderate size tokamak (major radius = 1.75 m) that is capable of 2 to 3 s… more
Date: September 1, 1984
Creator: Zuhr, R.A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Analysis of surface currents on the CTX mesh flux conserver

Description: The use of discharge cleaning and a mesh structure for the flux conserver have led to hotter, less resistive, spheromak configurations in the CTX experiment. Achievement of these conditions has been accompanied by the appearance of oscillations - most notably seen on magnetic probe signals - that were previously not present. These oscillations are observed both during the sustainment (V/sub gun/ not equal to 0) and the decaying (V/sub gun/ = 0) phases of the discharge and are attributed to the … more
Date: February 1, 1984
Creator: Wright, B.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Influence of hot beam ions on MHD ballooning modes in tokamaks

Description: It has recently been proposed that the presence of high energy ions from neutral beam injection can have a strong stabilizing effect on kinetically-modified ideal MHD ballooning modes in tokamaks. In order to assess realistically the importance of such effects, a comprehensive kinetic stability analysis, which takes into account the integral equation nature of the basic problem, has been applied to this investigation. In the collisionless limit, the effect of adding small fractions of hot beam … more
Date: July 1, 1984
Creator: Rewoldt, G. & Tang, W.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Stellarator hybrids

Description: The present paper briefly reviews the subject of tokamak-stellarator and pinch-stellarator hybrids, and points to two interesting new possibilities: compact-torus-stellarators and mirror-stellarators.
Date: August 1, 1984
Creator: Furth, H.P. & Ludescher, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Confinement time and energy balance in the CTX spheromak

Description: The multipoint Thomson scattering diagnostic on CTX allows measurement of electron plasma pressure. The pressure correlates well with the poloidal flux function. Analysis using equilibrium models allows the (..beta..)/sub vol/ to be calculated from over 100 Thomson scattering profiles taken under standard conditions of spheromak operation where the plasma parameters vary widely within the discharge. The calculated tau/sub E/ increases with central core temperature and with density. The global m… more
Date: January 1, 1984
Creator: Barnes, C. W.; Henins, I.; Hoida, H. W. & Jarboe, T. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Steady-state operation of spheromaks by inductive techniques

Description: A method to maintain a steady-state spheromak configuration inductively using the S-1 Spheromak device is described. The S-1 Spheromak formation apparatus can be utilized to inject magnetic helicity continuously (C.W., not pulsed or D.C.) into the spheromak configuration after equilibrium is achieved in the linked mode of operation. Oscillation of both poloidal- and toroidal-field currents in the flux core (psi-phi Pumping), with proper phasing, injects a net time-averaged helicity into the pla… more
Date: April 1, 1984
Creator: Janos, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Use of isotopically-enriched carbon probes for erosion/deposition measurements in the ASDEX divertor

Description: An isotopic marker technique has been developed and used to measure near-surface erosion and carbon and impurity deposition on graphite samples in the ASDEX divertor chamber. Papyex graphite strips were enriched to approx. 20% /sup 13/C over the first 1000 A by ion implantation. The implanted /sup 13/C can be clearly distinguished from /sup 12/C of the host by Rutherford backscattering using 2.7 MeV /sup 4/He. Carbon erosion and deposition were determined from changes in the depth distribution … more
Date: January 1, 1984
Creator: Roberto, J.B.; Roth, J.; Taglauer, E. & Holland, O.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

High-performance TF coil design for the Toroidal Fusion Core Experiment (TFCX)

Description: The Toroidal Fusion Core Experiment (TFCX) is a proposed concept for an ignited, long-pulse, current-driven tokamak device. TF coil winding cross section in the inboard region is impacted by peak field 10 T, winding current density approx. 3500 A/cm/sup 2/, and peak nuclear heating rates 50 mW/cc. The winding utilizes a Nb/sub 3/Sn internally cooled cable superconductor (ICCS), which is a modified version of the conductor used in the Westinghouse LCP coil. These modifications include the increa… more
Date: January 1, 1984
Creator: Srivastava, V.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Mixed mode operation in CTX

Description: Mixed method of operation with input powers of 10 MW to 20-MW results in hotter (..delta..T/sub e/ approx. 30 eV) longer lived spheromaks (approx. 200 ..mu..s longer) than slow mode operation. However, a further increase in driving current is detrimental to the temperature of the spheromak (possibly due to the injection of impurities). In the mixed method, n = 2 oscillations no longer appear during the decay, apparently due to the sustainment of currents in the outer flux surfaces. This sustain… more
Date: January 1, 1984
Creator: Hoida, H. W.; Barnes, C. W.; Henins, I. & Jarboe, T. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Equilibrium and stability of the Los Alamos spheromak

Description: The open mesh flux conserver (MFC) on the Los Alamos spheromak (CTX) has been equipped with a large number of Rogowski loops measuring the current in the individual segments of the MFC, providing a complete picture of the surface current pattern induced by the equilibrium and oscillations of the confined plasma. An analysis was made of the data from these Rogowski loops.
Date: January 1, 1984
Creator: Marklin, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Sustained spheromak technology

Description: The goal of these experiments is to devise a technique for driving a spheromak using dc-powered electrodes. The reduction or elimination of pulsed power components in the spheromak source would result in more attractive reactors, and simpler, cheaper experiments. This is important as experiments get larger and approach reactor size. According to some concepts, the dc spheromak would operate with plasma injection so that it would clean up any impurities produced during its formation. These featu… more
Date: January 1, 1984
Creator: Platts, D. A.; Sherwood, A. R.; Jarboe, T. R.; Linford, R. K.; Hoida, H. W. & Henins, I.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Sustainment dynamo reexamined: nonlocal electrical conductivity of plasma in a stochastic magnetic field

Description: The plasma dynamo is both an intriguing and a practical concept. The intrigue derives from attempting to explain naturally occurring and man-made plasmas whose strong field-aligned currents j/sub parallel/ apparently disobey the most naive Ohm's law j/sub parallel/ = sigma/sub parallel/E/sub parallel/. The practical importance derives from the dynamo's role both in formation and in sustainment of reversed-field pinch (RFP) and Spheromak fusion plasmas. We will examine certain features of the do… more
Date: January 1, 1984
Creator: Jacobson, Abram R. & Moses, Ronald W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen