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The National Spherical Torus Experiment (NSTX) has demonstrated the advantages of low aspect ratio geometry in accessing high toroidal and normalized plasma beta, and βN ≡ 108⟨βt⟩ aB0/Ip. Experiments have reached βt = 39% and βN = 7.2 through boundary and profile optimization. High βN plasmas can exceed the ideal no-wall stability limit, βNno−wall, for periods much greater than the wall eddy current decay time. Resistive wall mode (RWM) physics is studied to understand mode stabilization in these plasmas. The toroidal mode spectrum of unstable RWMs has been measured with mode number n up to 3. The critical rotation frequency of Bondeson–Chu, Ωcrit = ωA/(4q2), describes well the RWM stability of NSTX plasmas when applied over the entire rotation profile and in conjunction with the ideal stability criterion. Rotation damping and global rotation collapse observed in plasmas exceeding βNno−wall differs from the damping observed during tearing mode activity and can be described qualitatively by drag due to neoclassical toroidal viscosity in the helically perturbed field of an ideal displacement. Resonant field amplification of an applied n = 1 field perturbation has been measured and increases with increasing βN. Equilibria are reconstructed including measured ion and electron pressure, toroidal rotation and flux isotherm constraint in plasmas with core rotation ωϕ/ωA up to 0.48. Peak pressure shifts of 18% of the minor radius from the magnetic axis have been reconstructed.

Background:Laparoscopic radical cystectomy (LRC) is increasingly being used for muscle-invasive bladder cancer. However, high levels of clinical evidence comparing laparoscopic vs open radical cystectomy (ORC) are lacking.Methods:A prospective randomised controlled clinical trial comparing LRC vs ORC in patients undergoing radical cystectomy for bladder cancer. Thirty-five patients were eligible for final analysis in each group.Results:The median follow-up was 26 months (range, 4–59 months) for laparoscopic vs 32 months (range, 6–60 months) for ORC. Significant differences were noted in operative time, estimated blood loss (EBL), blood transfusion rate, analgesic requirement, and time to resumption of oral intake. No significant differences were noted in the length of hospital stay, complication rate, lymph node yield (14.1±6.3 for LRC and 15.2±5.9 for ORC), positive surgical margin rate, postoperative pathology, or recurrence rate (7 for LRC and 8 for ORC). The 5-year recurrence-free survival with laparoscopic vs ORC was 78.5% vs 70.9%, respectively (P=0.773). The overall survival with laparoscopic vs ORC was 73.8% vs 67.4%, respectively (P=0.511).Conclusion:Our study demonstrated that LRC is superior to ORC in perioperative outcomes, including EBL, blood transfusion rate, and analgesic requirement. We found no major difference in oncologic outcomes. The number of patients is too small to allow for a final conclusion.