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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.12319">arXiv:2502.12319</a> <span> [<a href="https://arxiv.org/pdf/2502.12319">pdf</a>, <a href="https://arxiv.org/format/2502.12319">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> </div> <p class="title is-5 mathjax"> Enhancing Stellarator Accessibility through Port Size Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Baillod%2C+A">A. Baillod</a>, <a href="/search/physics?searchtype=author&query=Paul%2C+E+J">E. J. Paul</a>, <a href="/search/physics?searchtype=author&query=Elder%2C+T">T. Elder</a>, <a href="/search/physics?searchtype=author&query=Halpern%2C+J+M">J. M. Halpern</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.12319v1-abstract-short" style="display: inline;"> Access to the plasma chamber in a stellarator reactor is essential for maintenance and diagnostics. However, the complex geometry of stellarator coils, often characterized by their strong twisting, can severely limit the space available for access ports. This study introduces a novel optimization approach in which access ports are represented as closed curves on the plasma boundary. By carefully s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.12319v1-abstract-full').style.display = 'inline'; document.getElementById('2502.12319v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.12319v1-abstract-full" style="display: none;"> Access to the plasma chamber in a stellarator reactor is essential for maintenance and diagnostics. However, the complex geometry of stellarator coils, often characterized by their strong twisting, can severely limit the space available for access ports. This study introduces a novel optimization approach in which access ports are represented as closed curves on the plasma boundary. By carefully selecting a set of objectives and penalties related to the access port, we demonstrate the first stellarator coil optimization explicitly targeting improved access port size. The trade-off between magnetic field quality and port size is analyzed through the Pareto front of their respective objectives. The optimal location of a port is explained using a current potential approach. Finally, we show that additional shaping coils, such as windowpane coils, can enable the crossing of the Pareto front to achieve superior configurations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.12319v1-abstract-full').style.display = 'none'; document.getElementById('2502.12319v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">41 pages, 18 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.01507">arXiv:2204.01507</a> <span> [<a href="https://arxiv.org/pdf/2204.01507">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Classical Physics">physics.class-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.106.L063201">10.1103/PhysRevE.106.L063201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Space-charge-limited current density for nonplanar diodes with monoenergetic emission using Lie-point symmetries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Harsha%2C+N+R+S">N. R. Sree Harsha</a>, <a href="/search/physics?searchtype=author&query=Halpern%2C+J+M">Jacob M. Halpern</a>, <a href="/search/physics?searchtype=author&query=Darr%2C+A+M">Adam M. Darr</a>, <a href="/search/physics?searchtype=author&query=Garner%2C+A+L">Allen L. Garner</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.01507v1-abstract-short" style="display: inline;"> Understanding space-charge limited current density (SCLCD) is fundamentally and practically important for characterizing many high-power and high-current vacuum devices. Despite this, no analytic equations for SCLCD with nonzero monoenergetic initial velocity have been derived for nonplanar diodes from first principles. Obtaining analytic equations for SCLCD for nonplanar geometries is often compl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.01507v1-abstract-full').style.display = 'inline'; document.getElementById('2204.01507v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.01507v1-abstract-full" style="display: none;"> Understanding space-charge limited current density (SCLCD) is fundamentally and practically important for characterizing many high-power and high-current vacuum devices. Despite this, no analytic equations for SCLCD with nonzero monoenergetic initial velocity have been derived for nonplanar diodes from first principles. Obtaining analytic equations for SCLCD for nonplanar geometries is often complicated by the nonlinearity of the problem and over constrained boundary conditions. In this letter, we use the canonical coordinates obtained by identifying Lie-point symmetries to linearize the governing differential equations to derive SCLCD for any orthogonal diode. Using this method, we derive exact analytic equations for SCLCD with a monoenergetic injection velocity for one-dimensional cylindrical, spherical, tip-to-tip (t-t), and tip-to-plate (t-p) diodes. We specifically demonstrate that the correction factor from zero initial velocity to monoenergetic emission depends only on the initial kinetic and electric potential energies and not on the diode geometry and that SCLCD is universal when plotted as a function of the canonical gap size. We also show that SCLCD for a t-p diode is a factor of four larger than a t-t diode independent of injection velocity. The results reduce to previously derived results for zero initial velocity using variational calculus and conformal mapping. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.01507v1-abstract-full').style.display = 'none'; document.getElementById('2204.01507v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 3 figures</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div 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