Production of the 1.5 GHz fundamental power couplers for VSR demo

Research Instruments RI and Thales have been pro ducing the first two prototype 1.5 GHz fundamental power couplers for the VSR Variable pulse length Storage Ring DEMO since early 2021 and delivered these prototypes in late March 2023. These couplers are designed to provide up to 16 kW CW power to two 1.5 GHz superconducting cavities of the VSR DEMO module and provide variable coupling with a Qext range from 6 106 to 6 107. The paper describes the challenges in fabricating a scaled coupler and provides details on the modifications to the design as a re sult of these challenges. The impact of the late stage design modification is discussed along with how this affects future conditioning plan

Final Design Studies for the VSR DEMO 1.5 GHz Coupler

With the 1.5 GHz couplers for VSR DEMO are now in the manufacturing stages, the studies that led to the final coupler design will be presented. The system specific constraints and design modifications that combat the challenges of; thermomechanical stresses, HOM propagation and dimensional constraints are explored. This includes S Parameter analysis, an in depth study of the coupling factor, and multipacting studies for the average 1.5 kW and peak 16 kW powe

High-altitude pulmonary hypertension is associated with a free radical-mediated reduction in pulmonary nitric oxide bioavailability

High altitude (HA)-induced pulmonary hypertension may be due to a free radical-mediated reduction in pulmonary nitric oxide (NO) bioavailability. We hypothesised that the increase in pulmonary artery systolic pressure (PASP) at HA would be associated with a net transpulmonary output of free radicals and corresponding loss of bioactive NO metabolites. Twenty-six mountaineers provided central venous and radial arterial samples at low altitude (LA) and following active ascent to 4559 m (HA). PASP was determined by Doppler echocardiography, pulmonary blood flow by inert gas re-breathing, and vasoactive exchange via the Fick principle. Acute mountain sickness (AMS) and high-altitude pulmonary oedema (HAPE) were diagnosed using clinical questionnaires and chest radiography. Electron paramagnetic resonance spectroscopy, ozone-based chemiluminescence and ELISA were employed for plasma detection of the ascorbate free radical (A·−), NO metabolites and 3-nitrotyrosine (3-NT). Fourteen subjects were diagnosed with AMS and three of four HAPE-susceptible subjects developed HAPE. Ascent decreased the arterio-central venous concentration difference (a-cvD) resulting in a net transpulmonary loss of ascorbate, α-tocopherol and bioactive NO metabolites (P < 0.05 vs. LA). This was accompanied by an increased a-cvD and net output of A·− and lipid hydroperoxides (P < 0.05 vs. sea level, SL) that correlated against the rise in PASP (r= 0.56–0.62, P < 0.05) and arterial 3-NT (r= 0.48–0.63, P < 0.05) that was more pronounced in HAPE. These findings suggest that increased PASP and vascular resistance observed at HA are associated with a free radical-mediated reduction in pulmonary NO bioavailability