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Vannucci, A.
Sao Paulo Univ., SP (Brazil). Inst. de Fisica1987
Sao Paulo Univ., SP (Brazil). Inst. de Fisica1987
AbstractAbstract
[en] The disruptive instabilities in the TBR-1 tokamak of the Plasma Physics Laboratory of the Institute of Physics-USP were investigated by using surface-barrier detectors and Mirnov magnetic coils, measuring soft X-ray emited by the plasma and poloidal magnetic fluctuations, respectively. Minor and major disruptions, as well sawteeth oscillations, were identified at the TBR-1 discharges, and their main characteristics were studied. Comparing the measured period of the internal disruptions (sawteeth) with the ones expected from scaling laws, good agreements is reached. The measured sawteeth crashes agree with the values expected from the Kadomtsev's model. External helical fields (CHR), corresponding to m/n=2/1 helicity were produced in order to inhibit or criate disruptive instabilities. A strong weakening of the mhd activity, present in the TBR-1 discharges, was clearly detected. The soft X-ray detection system, projected and constructed for this work, was used to obtain the electron temperatures of regions close to the center of the plasma column (T(r=0) ∼ 205 eV and T(r ± 3,8) ∼ 85 eV), using the absorbing foils method. Using the Spitzer formula, Z sub (eff) values were also obtained. (author)
[pt]
As instabilidades de disruptura que surgem no tokamak TBR-1, do Laboratorio de Plasmas do Instituto de Fisica da USP, foram investigadas atraves de dois diagnosticos basicos, constituidos por detetores barreira-de-superficie e por bobinas magneticas de Mirnov, que medem, respectivamente, a emissao de raios-X moles emitidos pelo plasma e as flutuacoes no campo magnetico poloidal. A presenca de disrupturas maiores e menores, bem como de flutuacoes dentes-de-serra, foram identificadas nas descargas do TBR-1, registrando-se as suas caracterisiticas principais. Comparacoes realizadas entre os valores experimentais do periodo das disrupturas internas (dentes-de-serra) com os previstos por leis empiricas existentes, mostraram-se bastante compativeis. Os tempos de queda abrupta dos dentes-de-serra medidos mostratam-se em concordancia com aqueles que seriam preditos pelo modelo de Kadomtsev para explicar a origem dessas disrupturas. Campos helicoidais externos (CHR), com helicidade m/n=2/1, foram acionados na tentativa de inibir/ativar as instabilidades de disruptura. Pode-se realmente constatar um efetivo amortecimento na intensidade da atividade mhd presente nas descargas do YBR-1. O sistema de detecao de raios-X de baixas energias, projetado e construido em funcao deste trabalho, foi utilizado na determinacao da temperatura de eletrons em regioes proximas ao centro da coluna de plasma (T(r=0) ∼ 205 eV e T(r= ± 3,8 cm) ∼ 85 eV), atraves do metodo dos absorvedores. Medidas do Zefetivo puderam, ser obtidas atraves da formula de Spitzer. (autor)Original Title
Instabilidades de disruptura no TBR-1
Primary Subject
Source
1987; 178 p; Tese (Ph.D.).
Record Type
Miscellaneous
Literature Type
Thesis/Dissertation
Report Number
Country of publication
CLOSED PLASMA DEVICES, DETECTION, ELECTRIC COILS, ELECTRICAL EQUIPMENT, ELECTROMAGNETIC RADIATION, EQUIPMENT, INSTABILITY, IONIZING RADIATIONS, MEASURING INSTRUMENTS, OSCILLATIONS, RADIATION DETECTION, RADIATION DETECTORS, RADIATIONS, SEMICONDUCTOR DETECTORS, THERMONUCLEAR DEVICES, TOKAMAK DEVICES, X RADIATION
LanguageLanguage
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Caldas, I.L.; Vannucci, A.
Sao Paulo Univ. (Brazil). Inst. de Fisica1985
Sao Paulo Univ. (Brazil). Inst. de Fisica1985
AbstractAbstract
[en] A phenomenological introduction of some of the main theoretical and experimental features on equilibrium and instabilities in tokamaks is presented. In general only macroscopic effects are considered, being the plasma described as a fluid. (L.C.)
[pt]
Apresenta-se uma introducao fenomenologica de algumas das principais caracteristicas teoricas e experimentais sobre equilibrio e instabilidades em tokamaks. Em geral sao considerados apenas efeitos macroscopicos, sendo o plasma descrito como um fluido. (Autor)Original Title
Equilibrio e instabilidades do plasma em tokamaks
Primary Subject
Source
1985; 79 p
Record Type
Report
Literature Type
Numerical Data
Report Number
Country of publication
LanguageLanguage
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Vannucci, A.; Oliveira, K.A.; Tajima, T.
Texas Univ., Austin, TX (United States). Inst. for Fusion Studies. Funding organisation: USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States)1998
Texas Univ., Austin, TX (United States). Inst. for Fusion Studies. Funding organisation: USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States)1998
AbstractAbstract
[en] A feed-forward neural network with two hidden layers is used in this work to forecast major and minor disruptive instabilities in TEXT discharges. Using soft X-ray signals as input data, the neural net is trained with one disruptive plasma pulse, and a different disruptive discharge is used for validation. After being properly trained the networks, with the same set of weights. is then used to forecast disruptions in two others different plasma pulses. It is observed that the neural net is able to predict the incoming of a disruption more than 3 ms in advance. This time interval is almost three times longer than the one already obtained previously when magnetic signal from a Mirnov coil was used to feed the neural networks with. To our own eye we fail to see any indication of an upcoming disruption from the experimental data this far back from the time of disruption. Finally, from what we observe in the predictive behavior of our network, speculations are made whether the disruption triggering mechanism would be associated to an increase of the m = 2 magnetic island, that disturbs the central part of the plasma column afterwards or, in face of the results from this work, the initial perturbation would have occurred first in the central part of the plasma column, within the q = 1 magnetic surface, and then the m = 2 MHD mode would be destabilized afterwards
Primary Subject
Secondary Subject
Source
Feb 1998; 25 p; IFSR--809; CONTRACT FG03-96ER54346; ALSO AVAILABLE FROM OSTI AS DE98004492; NTIS; INIS; US GOVT. PRINTING OFFICE DEP
Record Type
Report
Report Number
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Pillon, M.; Vannucci, A.
Contributions to the 3rd International Symposium on Radiation Physics. Ferrara, September 30, 19851985
Contributions to the 3rd International Symposium on Radiation Physics. Ferrara, September 30, 19851985
AbstractAbstract
[en] The 1.01 MeV triton burn-up has been investigated in the FT plasma by means of the activation technique. The 14 MeV neutrns produced by triton burn-up have been measured with the activation reaction Cu63 (n, 2n) Cu62 which has a threshold of 10.9 MeV
Primary Subject
Source
ENEA, Rome (Italy); 70 p; 1985; p. 65-70; 3. International Symposium on Radiation Physics; Ferrara (Italy); 30 Sep 1985
Record Type
Report
Literature Type
Conference
Report Number
Country of publication
BARYON REACTIONS, BARYONS, BEAMS, BETA DECAY RADIOISOTOPES, BETA-PLUS DECAY RADIOISOTOPES, CHARGED PARTICLES, CLOSED PLASMA DEVICES, COPPER ISOTOPES, ELECTRON CAPTURE RADIOISOTOPES, ELEMENTARY PARTICLES, EMISSION, ENERGY RANGE, FERMIONS, HADRON REACTIONS, HADRONS, INTERMEDIATE MASS NUCLEI, ISOTOPES, MEV RANGE, MINUTES LIVING RADIOISOTOPES, NUCLEAR REACTIONS, NUCLEI, NUCLEON BEAMS, NUCLEON REACTIONS, NUCLEONS, ODD-ODD NUCLEI, PARTICLE BEAMS, RADIOISOTOPES, TARGETS, THERMONUCLEAR DEVICES, TOKAMAK DEVICES
Reference NumberReference Number
Related RecordRelated Record
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Short communication
Original Title
Efeito de impurezas de baixo Z no plasma do tokamaka TBR-1
Primary Subject
Source
45. Annual Meeting of the Brazilian Society for the Advancement of Science; Recife, PE (Brazil); 11-16 Jul 1993
Record Type
Journal Article
Literature Type
Conference
Journal
Country of publication
LanguageLanguage
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
No abstract available
Original Title
Eletrofissao do 233U
Primary Subject
Source
32. Annual Meeting of the Brazilian Society for the Advancement of Science; Rio de Janeiro, Brazil; 6 - 12 Jul 1980; Published in summary form only.
Record Type
Journal Article
Literature Type
Conference
Journal
Cienc. Cult. (Sao Paulo) Supl; v. 32(7); p. 301
Country of publication
ACTINIDE NUCLEI, ALPHA DECAY RADIOISOTOPES, BEAMS, ELECTRON REACTIONS, ENERGY RANGE, ENERGY-LEVEL TRANSITIONS, EVEN-ODD NUCLEI, FISSION, HEAVY NUCLEI, ISOTOPES, LEPTON BEAMS, LEPTON REACTIONS, MEV RANGE, MULTIPOLE TRANSITIONS, NUCLEAR REACTION YIELD, NUCLEAR REACTIONS, NUCLEI, PARTICLE BEAMS, RADIOISOTOPES, URANIUM ISOTOPES, YEARS LIVING RADIOISOTOPES
LanguageLanguage
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] The configuration of the intersection of magnetic field lines with a poloidal surface for a plasma column in equilibrium in the small torus TBR-1 is obtained before and after the application of m=2 resonant helical fields (RHF). The results support the interpretation that the RHF actuate on the m=2 mode causing a strong decrease in the MHD activity. (author). 8 refs, 6 figs, 1 tab
Primary Subject
Source
International Atomic Energy Agency, Vienna (Austria); 208 p; Jul 1989; p. 61-66; Technical committee on research using small tokamaks; Nice (France); 10-11 Oct 1988
Record Type
Report
Literature Type
Conference
Report Number
Country of publication
Reference NumberReference Number
Related RecordRelated Record
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Published in summary form only
Original Title
Avaalicao de detetores barreira-de-superficie na deteccao de radiacao de plasma durante as descargas do TBR-1
Source
40. Annual Meeting of the Brazilian Society for the Advancement of Science; Sao Paulo, SP (Brazil); 10-16 Jul 1988
Record Type
Journal Article
Literature Type
Conference
Journal
Country of publication
LanguageLanguage
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Arruda Neto, J.D.T.; Vannucci, M.F.B.M.; Herdade, S.B.; Vannucci, A.; Nascimento, I.C. do.
Sao Paulo Univ. (Brazil). Inst. de Fisica1981
Sao Paulo Univ. (Brazil). Inst. de Fisica1981
AbstractAbstract
[en] The electrofission angular distribution of 232Th, in the energy interval 5.5-7 MeV, was measured. The analysis of substantial amount of E2 fission strength is concentrated near the fission barrier, corresponding to (8 +- 2)% of one energy weighted sum rule unity. (Author)
[pt]
Mede-se a distribuicao angular de eletrofissao do 232Th, no intervalo de energia de 5.5 a 7 MeV. A analise do coeficiente de E2 da distribuicao angular revelou que uma quantia substancial de intensidade de fissao, correspondendo a (8 +- 2)% de uma unidade de regra de soma ponderada de energia. (L.C.)Primary Subject
Secondary Subject
Source
Aug 1981; 14 p
Record Type
Report
Literature Type
Numerical Data
Report Number
Country of publication
ACTINIDE NUCLEI, ALPHA DECAY RADIOISOTOPES, DATA, DISTRIBUTION, ELECTRON REACTIONS, ENERGY RANGE, ENERGY-LEVEL TRANSITIONS, EVEN-EVEN NUCLEI, FISSION, FUNCTIONS, HEAVY NUCLEI, INFORMATION, ISOTOPES, LEPTON REACTIONS, MEV RANGE, MULTIPOLE TRANSITIONS, NUCLEAR REACTIONS, NUCLEI, NUMERICAL DATA, RADIOISOTOPES, THORIUM ISOTOPES, YEARS LIVING RADIOISOTOPES
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Investigations concerning the influence of Resonant Helical Fields (RHF) on confined plasmas have been already carried out in several tokamaks including the TBR-1 - a small tokamak with minor radius a=0.08m and major radius r=0.30m. This work, in particular, reports some detailed analysis done with the objective of determining the physical mechanisms that may give rise to disruptive instabilities, when RHF are applied. The external perturbations, corresponding to the components m/n=2/1, 3/1 and 4/1 were created by a set of helical windings located externally around the torus. The poloidal magnetic fluctuations were detected by a set of 10 pick-up coils placed inside the vacuum vessel. The output signals were Fourier-analysed and the time evolution of each MHD component, ranging from m=0 to m=4, could be separately obtained. Spectral analysis performed over some time intervals, along the discharges, allowed the determination of the characteristic frequencies of the different modes before, during and after a disruption takes place. (author) 3 refs., 6 figs., 1 tab
Primary Subject
Source
1992 international conference on plasma physics; Innsbruck (Austria); 29 Jun - 3 Jul 1992
Record Type
Journal Article
Literature Type
Conference; Numerical Data
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
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