Effect of cold alpha-particle removal and fueling scenarios on power and particle balance in fusion plasma

Evolution in time of the plasma density, temperature and thermal alpha-particle density is considered under modeling of the helium ash removal. It is shown that slow changing in time of the helium ash density can be used for the operation path changing in fusion DT plasma. There is considered also the effect of different scenarios of fueling rates on the plasma operation path and steady state parameters. The temporal evolutions of the operating point during the ignition access and ignited operation phases are analyzed analytically and numerically. The main target of the study is the optimization of the plasma operation scenario in future fusion reactors including ITER. В работе рассмотрена эволюция во времени плотности плазмы, температуры и доли тепловых альфа-частиц при моделировании удаления холодных альфа-частиц. Показано, что медленное изменение во времени плотности холодных частиц может быть использовано для управления путем поджига в термоядерной дейтериево-тритиевой плазме. Также рассмотрено влияние различных сценариев ввода топлива на режимы горения плазмы и на параметры в стационарном состоянии. Проведен численный и аналитический анализ эволюции параметров плазмы во времени, влияние на положение рабочей точки на пути достижения горения и непосредственно фазы горения. Основной задачей исследования является оптимизация сценариев поджига и горения плазмы в будущих термоядерных реакторах, включая ITER

D+D fusion products yield in torsatron Large Helical Device

In the present paper we study the possibility to obtain fusion products and control of fusion products amount in operating torsatron device, particularly Large Helical Device. The study is carried out on the base of the particle and power balance equations where the evolution of plasma parameters in time is being followed also. Access of the ignition and the steady operation for different fueling schemes is studied. There were developed the fueling scenarios which provide the amount of fusion products distinguished two orders magnitude amount. It is shown that varying the fueling rates (the source term in the balance equations) makes it possible to control the fusion product amounts two orders of the magnitude. В этой работе нами рассмотрена возможность получения продуктов синтеза и управления их количеством на современной установке торсатронного типа на примере Large Helical Device (LHD). Изучение проблемы проведено на основании уравнений баланса энергии и частиц с одновременным рассмотрением временной эволюции параметров плазмы. Изучены процессы достижения горения и работа в стационарном режиме для различных сценариев подачи топлива в экспериментальную установку. Разработаны такие сценарии подачи топлива в систему удержания, которые позволяют достигать превышения плотности продуктов синтеза на два порядка при равных затратах внешней мощности нагрева. Показано, что, изменяя закон подачи топлива в систему (исходные параметры в уравнениях баланса), можно управлять количеством образующихся продуктов синтеза в пределах двух порядков

Impurity ion removal with the use of drift resonance

Impurity ion removal in a toroidal magnetic trap with a helical field under time-dependent magnetic field perturbations is considered using guiding center equations. The ultimate goal is to find out ways to remove impurities from the confinement volume or to protect the confinement volume from impurity ion penetration in stellarator (torsatron) type traps

Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.Comment: 10 pages, 3 figure

Measurement of the Spin Structure of the Deuteron in the DIS Region

We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.Comment: 10 pages, 6 figures, subm. to PLB, revised: author list, Fig. 4, details adde

The COMPASS Experiment at CERN

The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

Search for the Phi(1860) Pentaquark at COMPASS

Narrow Xi-pi+- and Xi-bar+pi+- resonances produced by quasi-real photons have been searched for by the COMPASS experiment at CERN. The study was stimulated by the recent observation of an exotic baryonic state decaying into Xi-pi-, at a mass of 1862 MeV, interpreted as a pentaquark. While the ordinary hyperon states Xi(1530)^0 and Xi-bar(1530)^0 are clearly seen, no exotic baryon is observed in the data taken in 2002 and 2003.Comment: 10 pages, 5 figure