Edge radial electric field studies via charge exchange recombination spectroscopy on the Alcator C-Mod Tokamak

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 189-197).It is commonly accepted that ExB velocity shear is responsible for the suppression of edge turbulence, which reduces the losses of both energy and particles across magnetic field lines and results in the formation of edge transport barriers and high-confinement mode (H-mode) in tokamak plasmas. However, the self consistent evolution of the radial electric field profile (Er), pedestal shape and improvement in plasma confinement is not well understood. A better understanding of pedestal physics and the interplay between Er, turbulence suppression and pedestal formation should enable better control of edge transport and improve core confinement. A new, high-resolution, charge exchange recombination spectroscopy (CXRS) diagnostic has been installed on Alcator C-Mod to provide measurements of the B5+ population in the pedestal region. This diagnostic is capable of measuring the boron temperature, density, and poloidal and toroidal velocity with 3mm radial resolution and 5ms temporal resolution. These profiles, coupled with knowledge of the toroidal and poloidal magnetic fields, enable the determination of the edge radial electric field through the radial force balance equation. The new CXRS diagnostic has provided the first spatially resolved calculations of the radial electric field in the C-Mod edge and has made possible significant contributions to the study of pedestal physics. Detailed measurements of the boron population have been made in a variety of plasma regimes. The measured rotation profiles connect the SOL and core measurements and are consistent with both. The CXRS boron temperature profiles are observed to agree well with the Thomson Scattering electron temperature profiles in bothl shape and magnitude over a wide range of collisionalities. In H-mode plasmas both the boron temperature and density profiles form clear pedestals, similar to what is observed in the electron channel. The edge toroidal rotation increases in the concurrent direction at the onset of H-mode confinement and the poloidal rotation in the pedestal region increases in the electron diamagnetic direction forming a narrow(cont.) peak (3-4mm) just inside of the LCFS. In Ohmic L-mode plasmas Er is positive near the last closed flux surface (LCFS) and becomes more negative with distance into the plasma. In H-mode plasmas E, is positive in the core, but forms a deep negative well, relative to its L-mode values, just inside of the LCFS. These results are qualitatively consistent with the observations made on other machines. However, the C-Mod H-mode Er wells are unprecedeited in depth (up to 300kV/m) and the narrow E, well widths (5mm), as compareJ to results from other tokamaks, suggest a scaling with machine size. The measured Er well widths have been compared to theoretical scalings for the edge pedestal and no significant correlation was observed with any of the predictions. In fact, very little variation of the E, well width is observed in general. Howc:ver, the depth of the E, well, or alternatively the magnitude of the E, shear (constant width), shows a strong correlation with improved plasma energy confinement. It also correlates well with the edge electron temperature and pressure pedestal heights (and gradients). It is not, however, very sensitive to variation in the edge electron density pedestal height. These results are an indication that the energy and particle transport have different relationships to Er, with energy transport more directly linked. The radial electric field results from ELM-free H-mode and I-mode plasmas support this interpretation.by Rachael Marie McDermott.Ph.D

Art as Meditation: A Mindful Inquiry into Educator Well-Being

Being prepared for the intensity and complexities that educators face in their work means building strategies for managing well-being. This qualitative study explored educators’ conceptualizations about their well-being using an arts-based, community-based participatory research (AB-CBPR) methodology. After a brief mindfulness meditation and contemplation of prompting questions, educators were invited to participate in drawing and writing reflections. The artifacts were coded to determine themes. Themes suggested the importance of human connectedness and interconnection, self care and nurturance, the healing qualities of the natural word, and the recognition that institutions need to provide space and resources to support educator well-being. The mindfulness-based art-as-meditation process was itself a salutogenic process and provided a means for developing a deeper understanding of educator well-being through a community-based participatory research approach

Numerical study of tearing mode seeding in tokamak X-point plasma

A detailed understanding of island seeding is crucial to avoid (N)TMs and their negative consequences like confinement degradation and disruptions. In the present work, we investigate the growth of 2/1 islands in response to magnetic perturbations. Although we use externally applied perturbations produced by resonant magnetic perturbation (RMP) coils for this study, results are directly transferable to island seeding by other MHD instabilities creating a resonant magnetic field component at the rational surface. Experimental results for 2/1 island penetration from ASDEX Upgrade are presented extending previous studies. Simulations are based on an ASDEX Upgrade L-mode discharge with low collisionality and active RMP coils. Our numerical studies are performed with the 3D, two fluid, non-linear MHD code JOREK. All three phases of mode seeding observed in the experiment are also seen in the simulations: first a weak response phase characterized by large perpendicular electron flow velocities followed by a fast growth of the magnetic island size accompanied by a reduction of the perpendicular electron velocity, and finally the saturation to a fully formed island state with perpendicular electron velocity close to zero. Thresholds for mode penetration are observed in the plasma rotation as well as in the RMP coil current. A hysteresis of the island size and electron perpendicular velocity is observed between the ramping up and down of the RMP amplitude consistent with an analytically predicted bifurcation. The transition from dominant kink/bending to tearing parity during the penetration is investigated

Feasibility study for a community based intervention for adults with severe chronic fatigue syndrome/ME

Background: Chronic Fatigue Syndrome/ME (CFS/ME) is characterised by debilitating fatigue with many bedbound patients. The study aims were: to determine whether a new intervention could be successfully delivered; to collect quantitative outcome data to guide the design of future studies; to explore qualitatively the experience of patients, carers and clinicians. Methods: Mixed-methods feasibility study with qualitative and quantitative evaluation. Participants: 12 UK patients who were housebound with severe CFS/ME. Intervention: Based on recovery skills identified through a 2.5 year Patient and Public Involvement development process involving individuals with first-hand experience of recovery from CFS/ME, as well as current patients and clinicians. The resulting one year intervention, delivered by a multi-disciplinary team, included domiciliary therapy visits and optional peer support group. Quantitative outcome measures: Patient-reported and therapist-reported outcome measures (including fatigue, physical function, anxiety, depression and other variables) and electronic activity measurement. Results: The study recruited and engaged twelve participants with no serious adverse events or dropouts. At end of intervention, 5/12 participants had improved in fatigue, physical function. Group mean scores improved overall for fatigue (Chalder fatigue scale), physical function (activity and physical function scale) and anxiety. Qualitative interviews suggested that the intervention was acceptable to patients, whilst also highlighting suggestions for improvement. Participants will be followed up for a further year to find out if improvements are sustained. Conclusion: This is the largest study ever conducted in severe CFS/ME and shows significant recovery suggesting further studies are indicated. Treatment is uniquely based on a patient inspired intervention

Paradoxical family practices: LGBTQ+ young people, mental health and wellbeing

This article will explore how LGBTQ+ young people sustain, and in some cases survive, family relationships. We develop the concept of ‘paradoxical family practices’ and use this to demonstrate the ways in which LGBTQ+ young people manage family life through everyday emotion work. This highlights: (1) how families ordinarily navigate heteronormativity and ‘issues’ of gender/sexuality; (2) the efficacy of ‘paradoxical family practices’ as a conceptual tool; (3) the value of emotion-centred multiple qualitative methods to explore the lives of LGBTQ+ young people and mental health. Findings derive from a small-scale UK study funded by the Wellcome Trust (UNS39780) and were generated through a two-stage methodology comprising digital/paper emotion maps and qualitative interviews with LGBTQ+ young people aged 16–25 (n = 12) followed by diary methods and follow-up interviews (n = 9). Interviews were also completed with ‘family members’ (n = 7)

Targeting Acid Ceramidase to Improve the Radiosensitivity of Rectal Cancer.

Previous work utilizing proteomic and immunohistochemical analyses has identified that high levels of acid ceramidase (AC) expression confers a poorer response to neoadjuvant treatment in locally advanced rectal cancer. We aimed to assess the radiosensitising effect of biological and pharmacological manipulation of AC and elucidate the underlying mechanism. AC manipulation in three colorectal cancer cell lines (HT29, HCT116 and LIM1215) was achieved using siRNA and plasmid overexpression. Carmofur and a novel small molecular inhibitor (LCL521) were used as pharmacological AC inhibitors. Using clonogenic assays, we demonstrate that an siRNA knockdown of AC enhanced X-ray radiosensitivity across all colorectal cancer cell lines compared to a non-targeting control siRNA, and conversely, AC protein overexpression increased radioresistance. Using CRISPR gene editing, we also generated AC knockout HCT116 cells that were significantly more radiosensitive compared to AC-expressing cells. Similarly, two patient-derived organoid models containing relatively low AC expression were found to be comparatively more radiosensitive than three other models containing higher levels of AC. Additionally, AC inhibition using carmofur and LCL521 in three colorectal cancer cell lines increased cellular radiosensitivity. Decreased AC protein led to significant poly-ADP ribose polymerase-1 (PARP-1) cleavage and apoptosis post-irradiation, which was shown to be executed through a p53-dependent process. Our study demonstrates that expression of AC within colorectal cancer cell lines modulates the cellular response to radiation, and particularly that AC inhibition leads to significantly enhanced radiosensitivity through an elevation in apoptosis. This work further solidifies AC as a target for improving radiotherapy treatment of locally advanced rectal cancer

Family Trouble: Heteronormativity, emotion work and queer youth mental health

Conflict with the family about sexual orientation and gender diversity is a key risk factor associated with poor mental health in youth populations. Findings presented here derive from a UK study that employed an interdisciplinary critical mental health approach that de-pathologized emotional distress and conceptualised families as social and affective units that are created through everyday practices. Our aim was to explore how family relationships foster, maintain or harm the mental health and wellbeing of LGBTQ+ youth. Data were generated through exploratory visual, creative and digital qualitative methods in two phases. Phase 1 involved digital/paper emotion maps and interviews with LGBTQ+ youth aged 16-25 (n=12) and family member/mentor interviews (n=7). Phase 2 employed diary methods and follow-up interviews (n=9). The data analytic strategy involved three stages: individual case analysis; cross-sectional thematic analysis; and metainterpretation. We found that family relationships impacted on queer youth mental health in complex ways that were related to the establishment of their autonomous queer selves, the desire to remain belonging to their family and the need to maintain a secure environment. The emotion work involved in navigating identity, belonging and security was made difficult because of family heteronormativity, youth autonomy and family expectations and had a stark impact on queer youth mental health and wellbeing. Improving the mental health of LGBTQ+ youth requires a much deeper understanding of the emotionality of family relationships and the difficulties negotiating these as a young person

Outcomes following SARS-CoV-2 infection in patients with primary and secondary immunodeficiency in the UK

In March 2020, the United Kingdom Primary Immunodeficiency Network (UKPIN) established a registry of cases to collate the outcomes of individuals with PID and SID following SARS-CoV-2 infection and treatment. A total of 310 cases of SARS-CoV-2 infection in individuals with PID or SID have now been reported in the UK. The overall mortality within the cohort was 17.7% (n = 55/310). Individuals with CVID demonstrated an infection fatality rate (IFR) of 18.3% (n = 17/93), individuals with PID receiving IgRT had an IFR of 16.3% (n = 26/159) and individuals with SID, an IFR of 27.2% (n = 25/92). Individuals with PID and SID had higher inpatient mortality and died at a younger age than the general population. Increasing age, low pre-SARS-CoV-2 infection lymphocyte count and the presence of common co-morbidities increased the risk of mortality in PID. Access to specific COVID-19 treatments in this cohort was limited: only 22.9% (n = 33/144) of patients admitted to the hospital received dexamethasone, remdesivir, an anti-SARS-CoV-2 antibody-based therapeutic (e.g. REGN-COV2 or convalescent plasma) or tocilizumab as a monotherapy or in combination. Dexamethasone, remdesivir, and anti-SARS-CoV-2 antibody-based therapeutics appeared efficacious in PID and SID. Compared to the general population, individuals with PID or SID are at high risk of mortality following SARS-CoV-2 infection. Increasing age, low baseline lymphocyte count, and the presence of co-morbidities are additional risk factors for poor outcome in this cohort

Exploring fusion-reactor physics with high-power electron cyclotron resonance heating on ASDEX Upgrade

The electron cyclotron resonance heating (ECRH) system of the ASDEX Upgrade tokomak has been upgraded over the last 15 years from a 2MW, 2 s, 140 GHz system to an 8MW, 10 s, dual frequency system (105/140 GHz). The power exceeds the L/H power threshold by at least a factor of two, even for high densities, and roughly equals the installed ion cyclotron range of frequencies power. The power of both wave heating systems together (>10MW in the plasma) is about half of the available neutral beam injection (NBI) power, allowing significant variations of torque input, of the shape of the heating profile and of Qe/Qi, even at high heating power. For applications at a low magnetic field an X3-heating scheme is routinely in use. Such a scenario is now also forseen for ITER to study the first H-modes at one third of the full field. This versatile system allows one to address important issues fundamental to a fusion reactor: H-mode operation with dominant electron heating, accessing low collisionalities in full metal devices (also related to suppression of edge localized modes with resonant magnetic perturbations), influence of Te/Ti and rotational shear on transport, and dependence of impurity accumulation on heating profiles. Experiments on all these subjects have been carried out over the last few years and will be presented in this contribution. The adjustable localized current drive capability of ECRH allows dedicated variations of the shape of the q-profile and the study of their influence on non-inductive tokamak operation (so far at q$_{95}$>5.3). The ultimate goal of these experiments is to use the experimental findings to refine theoretical models such that they allow a reliable design of operational schemes for reactor size devices. In this respect, recent studies comparing a quasi-linear approach (TGLF) with fully non-linear modeling (GENE) of non-inductive high-beta plasmas will be reported