Neutral density profiles are measured on the outboard midplane of the National Spherical Torus Experiment Upgrade (NSTX-U) using a two dimensional camera (ENDD, edge neutral density diagnostic) filtered for deuterium Balmer α (D _α ) emission interpreted via simulations using the Monte Carlo neutral transport code DEGAS 2. Deuterium atomic densities n _D are calculated by inverting the line-integrated D _α brightness and using local measurements of electron density n _e and temperature T _e to determine atomic rate coefficients. The assumptions used in the derivation of n _D from D _α emissivity are validated using DEGAS 2 to estimate contributions to emissivity due to electron impact excitation and molecular processes. Experimental measurements and DEGAS 2 simulations are compared over a database of L- and H-mode discharges, showing good agreement in D _α emissivity profiles. Residual disagreement between experiment and simulations is suggestive of the possible role of intermittent transport and uncertainties in the molecular data. DEGAS 2 simulations are further used to complement the ENDD diagnostic, extracting neutral (atomic and molecular) densities at locations where the ENDD measurement are not made or where the assumptions used in the ENDD analysis are not valid. Deuterium atomic densities and ionization profiles on the outer midplane are compared for L-mode and H-mode discharges in NSTX-U. One-way coupling of DEGAS 2 to UEDGE multi-fluid simulations constrained by experimental data is used to study edge fueling and neutral penetration in NSTX-U discharges.

中性密度分布上使用二维照相机国家球形环实验升级（NSTX-U）的外侧平面测量（ENDD，边缘中性密度诊断）过滤以氘巴尔末α（d _α）使用蒙特卡罗经由模拟发射解释卡罗中性输运代码DEGAS 2.氘原子密度ñ _d是通过反转线积分d计算_α亮度，并使用电子密度的局部测量ñ _Ë和温度Ť _ë来确定原子率系数。在的推导使用的假设ñ _d从d _α 使用DEGAS 2验证了发射率，以估算由于电子碰撞激发和分子过程对发射率的贡献。实验测量和DEGAS 2个仿真在L-和H模式放电的数据库进行比较，示出了d吻合_α 发射率剖面。实验和模拟之间的残留分歧表明了间歇传输的可能作用和分子数据中的不确定性。进一步使用DEGAS 2模拟来补充ENDD诊断，在未进行ENDD​​测量或在ENDD分析中使用的假设无效的位置提取中性（原子和分子）密度。比较了NSTX-U中L型和H型放电的外中平面上的氘原子密度和电离曲线。在实验数据的约束下，DEGAS 2与UEDGE多流体模拟的单向耦合用于研究NSTX-U放电中的边缘加油和中性渗透。