jats:titleAbstract</jats:title> jats:pDIII-D plasmas are compared for two upper divertor configurations: with the outer strike point on the small angle slot (SAS) divertor target and with the outer strike point on the horizontal divertor target (HT). Scanning the vertical distance between the magnetic null point and the divertor target over a range 0.10–0.16 m is shown to increase the threshold power, jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miP</mml:mi> mml:mrow mml:mith</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, and edge plasma power, jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miP</mml:mi> mml:mrow mml:miLoss</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, for the low-to-high confinement (L–H) and H–L transitions respectively, by up to a factor of 1.4. The X-point height scans were performed at three L-mode core plasma line average electron densities, jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:mrow mml:mover mml:min</mml:mi> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> mml:mrow <mml:mi mathvariant="normal">e</mml:mi> </mml:mrow> </mml:msub> mml:mo=</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> 1.2, 2.2 and 3.6 jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:mo×</mml:mo> mml:msup mml:mn10</mml:mn> mml:mrow mml:mn19</mml:mn> </mml:mrow> </mml:msup> <mml:mstyle scriptlevel="0" /> mml:msup mml:mrow <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> mml:mrow mml:mo−</mml:mo> mml:mn3</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>, to investigate the density dependence of divertor magnetic configuration influence on jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miP</mml:mi> mml:mrow mml:mith</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn5.gif" xlink:type="simple" /> </jats:inline-formula>. The X-point height, jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miZ</mml:mi> mml:mtextx-pt</mml:mtext> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>, was further extended across the range 0.16–0.22 m with the more open HT divertor configuration, for which a clear decrease in jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miP</mml:mi> mml:mrow mml:mith</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn7.gif" xlink:type="simple" /> </jats:inline-formula> with increasing jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miZ</mml:mi> mml:mtextx-pt</mml:mtext> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn8.gif" xlink:type="simple" /> </jats:inline-formula> is observed. The dependence of jats:inline-formula jats:tex-math</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mrow mml:msub mml:miP</mml:mi> mml:mtextth</mml:mtext> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ppcfad30c2ieqn9.gif" xlink:type="simple" /> </jats:inline-formula> on divertor magnetic geometry is further investigated using a time-dependent probability density function (PDF) model and information geometry to elucidate the roles played by pedestal plasma turbulence and perpendicular velocity flows. The degree of stochasticity of the plasma turbulence is observed to be sensitive to the plasma heating rate. The calculated square of the information rate shows changes in the relative density fluctuations and perpendicular velocity PDFs begin 2–5 ms prior to the L–H transition for three plasmas; providing a crucial measurement of the dynamic timescale of external transport barrier formation. Additionally, both information length and rate provide potential predictors of the L–H transition for these plasmas.</jats:p>