Electromagnetic oscillations at the edge of the Uragan-3M plasma

In the Uragan-3M torsatron the plasma is ICRF heated with the use of antennas of different types. The objective of this work is to study the electromagnetic wave propagation outside the plasma confinement volume and the effect of these waves on confined plasma behavior during RF-heating.В торсатроне Ураган-3М плазма нагревается ВЧ-волнами вблизи ионно-циклотронного резонанса антеннами различных типов. Целью настоящей работы является изучение распространения электромагнитных волн вне объема удержания и влияния этих волн на параметры плазмы в течение разряда.У торсатроні Ураган-3М плазма нагрівається ВЧ-хвилями поблизу іонного-циклотронного резонансу антенами різних типів. Метою цієї роботи є вивчення поширення електромагнітних хвиль поза обсягу утримання і впливу цих хвиль на параметри плазми протягом розряду

Transition to the improved confinement mode in torsatron U-3M in range of rare collision frequencies

Transition to the mode of improved plasma confinement in U-3M facility earlier was discussed in works [1-3]. In these studies discussed the various processes in the confinement volume and in the peripheral plasma that accompany the transition process. Study of plasma confinement and process of transition into the mode of improved confinement just at rare collisions between plasma particles is very important because future fusion reactor based on a toroidal magnetic trap will operate under plasma parameters with rare collision frequencies (“banana” mode). The peculiarity of experiments on torsatron U-3M is that they are conducted at small density ne ≤ 2×10^12 cm^-3 and, thereby, the frequency of collisions in the confinement area is in the "banana" mode [4]. And herewith, time of collisions is essentially smaller (up to several orders for electrons and up to the order for ions) than the lifetime of plasma particles. It ensures maxwellization of distribution function and possibility to compare the obtained results with data from other experiments. The objective of this work is to study the main regularity of transition into the mode of improved confinement. Also it is interesting to compare the results with data from other facilities

Acute respiratory failure and the kinetics of neutrophil recovery in pediatric hematopoietic cell transplantation: a multicenter study

This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.In this multicenter study, we investigated the kinetics of neutrophil recovery in relation to acuity and survival among 125 children undergoing allogeneic hematopoietic cell transplantation (allo-HCT) who required invasive mechanical ventilation (IMV). Recovery of neutrophils, whether prior to or after initiation of IMV, was associated with a significantly decreased risk of death relative to never achieving neutrophil recovery. A transient increase in acuity (by oxygenation index and vasopressor requirements) occurred among a subset of the patients who achieved neutrophil recovery after initiation of IMV; 61.5% of these patients survived to discharge from the intensive care unit (ICU). Improved survival among patients who subsequently achieved neutrophil recovery on IMV was not limited to those with peri-engraftment respiratory distress syndrome. The presence of a respiratory pathogen did not affect the risk of death while on IMV but was associated with an increased length of IMV (p < 0.01). Among patients undergoing HCT who develop respiratory failure and require advanced therapeutic support, neutrophil recovery at time of IMV and/or presence of a respiratory pathogen should not be used as determining factors when counseling families about survival

Formation of ITB in the vicinity of rational surfaces in the Uragan-3M torsatron

It was shown that there is the possibility of ITB formation in the vicinity of rational surfaces in a torsatron magnetic configuration. The formation of ITB is accompanied by fast change of plasma poloidal rotation velocity, radial electric field and its shear and the decrease of plasma density fluctuations. After the ITB formation the transition to the improved plasma confinement takes place. The transition stars when electron temperature in the region of rational surfaces is sufficient to satisfy the condition υTe/uei>>2πR0 (here υTe is electron thermal velocity and uei is the frequency of ion – electron collisions, and R0 is the major radius of the torus). Such a regime can be maintained during the whole duration of RF discharge without any disturbances.Показано, що існує можливість формування внутрішнього теплового бар’єру (ВТБ) в плазмі ВЧ розряду в околиці раціональних поверхонь в торсатронній магнітній конфігурації. Формування ВТБ супроводжується бистрими змінами швидкості полоідального обертання плазми, радіального електричного поля и його шира і зменшенням флуктуацій густини плазми поблизу раціональних поверхонь. Після формування ВТБ спостерігається перехід в режим поліпшеного утримання плазми. Час переходу зменшується із збільшенням ВЧ потужності нагріву.Показано, что имеется возможность формирования внутреннего теплового барьера (ВТБ) в плазме ВЧ разряда в окрестности рациональных поверхностей в торсатронной магнитной конфигурации. Формирование ВТБ сопровождается быстрыми изменениями скорости полоидального вращения плазмы, радиального электрического поля и его шира и уменьшением флуктуаций плотности плазмы вблизи рациональных поверхностей. После формирования ВТБ наблюдается переход в режим улучшенного удержания плазмы. Время перехода сокращается с увеличением ВЧ мощности нагрева