Laura Galeotti

A high performance field-reversed configurationa)

Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over the past half-decade has contributed to striking improvements in confinement and stability. Further, the addition of electrically biased plasma guns at the ends, magnetic end plugs, and advanced surface conditioning led to dramatic reductions in turbulence-driven losses and greatly improved stability. Together, these enabled the build-up of a well-confined and dominant fast-ion population. Under such conditions, highly reproducible, macroscopically stable hot FRCs (with total plasma temperature of ∼1 keV) with record lifetimes were achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an intriguing path toward fusion reactors. This paper reviews key results and presents context for further interpretation.

Formation of a long-lived hot field reversed configuration by dynamically merging two colliding high-β compact toroidsa)

A high temperature field reversed configuration (FRC) has been produced in the newly built, world’s largest compact toroid (CT) facility, C-2, by colliding and merging two high-β CTs produced using the advanced field-reversed θ-pinch technology. This long-lived, stable merged state exhibits the following key properties: (1) apparent increase in the poloidal flux from the first pass to the final merged state, (2) significantly improved confinement compared to conventional θ-pinch FRCs with flux decay rates approaching classical values in some cases, (3) strong conversion from kinetic energy into thermal energy with total temperature (Te + Ti) exceeding 0.5 keV, predominantly into the ion channel. Detailed modeling using a new 2-D resistive magnetohydrodynamic (MHD) code, LamyRidge, has demonstrated, for the first time, the formation, translation, and merging/reconnection dynamics of such extremely high-β plasmas.

Recent breakthroughs on C-2U: Norman's legacy

Conventional field-reversed configurations (FRC) face notable stability and confinement concerns, which can be ameliorated by introducing and maintaining a significant fast ion population in the system. This is the conjecture first introduced by Norman Rostoker multiple decades ago and adopted as the central design tenet in Tri Alpha Energy’s advanced beam driven FRC concept. In fact, studying the physics of such neutral beam (NB) driven FRCs over the past decade, considerable improvements were made in confinement and stability. Next to NB injection, the addition of axially streaming plasma guns, magnetic end plugs, as well as advanced surface conditioning lead to dramatic reductions in turbulence driven losses and greatly improved stability. In turn, fast ion confinement improved significantly and allowed for the build-up of a dominant fast particle population. This recently led to the breakthrough of sustaining an advanced beam driven FRC, thereby demonstrating successful maintenance of trapped magnetic...

Plasma equilibria with multiple ion species: Equations and algorithm

Axisymmetric equilibrium of a magnetically confined plasma with multiple ion species is considered. To describe hot plasmas with isothermal surfaces, we adopt a formulation consistent with zero poloidal ion flow. This formulation includes all magnetic field components and also correctly includes all effects of toroidal ion rotation. There are two free surface functions for each species and a third which is determined by a differential equation relating surface functions per species. We have developed and implemented an algorithm for the solution of the resulting nonlinear equations and found solutions with large charge and mass contrast among the ion species for both compact (r = 0 included) and annular (r = 0 excluded) domains. Our solution method allows for arbitrary domain shapes, includes far-field conditions, and treats any combination of electrically conducting or insulating walls. Appropriate surface functions are used to describe the transition from closed to open field plasma in a reasonable mann...

Association of the hOCT1/ABCB1 genotype with efficacy and tolerability of imatinib in patients affected by chronic myeloid leukemia

PurposeThe present study was aimed at investigating whether imatinib pharmacogenetics is related to its pharmacodynamics in patients affected by chronic myeloid leukemia.MethodsThrough a procedure based on a sequence of classical statistics methods, we investigated the possible relationships between treatment efficacy/tolerability and combinations of time-independent variables as gender and genetic covariates in the form of single nucleotide polymorphisms (SNPs) or combinations thereof. Moreover, since the drug tolerability has a strong incidence on the discontinuation of the therapy, we investigated whether the time of manifestation of the most frequent toxic effects can be related to time-independent patients’ characteristics or not.ResultsWe found that a combination of two polymorphisms, namely hOCT1 c.480C>G (rs683369) and ABCB1 c.3435C>T (rs1045642), seems to play the role of predictor for imatinib in both efficacy and toxicity. Furthermore, the time of manifestation of edema toxicity is found to be associated to a combination of gender and ABCB1 c.3435C>T, whereas the time of manifestation of cramp toxicity appears related to gender.ConclusionsThe novelty of this study is dual: the achievement of results that potentially have a significant clinical interest and the demonstration that the adoption of composed covariates may represent a unique tool to study different aspects of the treatment with imatinib.