November 4 - 7, 2025

NLTE-13 Code Comparison Workshop

Institut Henri Poincaré, Paris, France

Advanced collisional-radiative (CR) models are essential tools in plasma spectroscopy, providing insights into plasma kinetics and spectra under conditions far from local thermodynamic equilibrium (LTE). Additionally, non-LTE atomic models are a key component in radiation-hydrodynamic simulations that support the design and interpretation of plasma experiments. Given their complexity, the verification and validation (V&V) of these CR models are of great importance. However, due to the difficulty of obtaining experimental benchmarks, computational comparisons and simulations remain the primary means for V&V efforts. The NLTE Workshops have been instrumental in fostering the development of such methodologies. The 13th edition of the Workshop will also feature a dedicated machine-learning session (See AI/ML Session), aimed at updating researchers on how state-of-the-art ML techniques are advancing CR modeling. This Workshop will be held at the Institut Henri Poincaré (Paris, France)from November 4th to 7th, 2025. It is supported by the Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and the Institut Henri Poincaré (IHP).

Time Line

Oct 7 - submission deadline

Oct 21 - online database accessible

Nov 3 - Informal reception (place TBD)

Nov 4 - Workshop opens

Nov 7 - Workshop adjourns

Registration

Similar to previous workshops, a necessary and sufficient condition for participation is the submission of at least one calculated case, unless you are an invited speaker for the AI/ML session. A detailed description of the cases and format requirements can be found in the Submission of calculatoins. For details on file uploads, please contact Yuri Ralchenko (yuri.ralchenko@nist.gov).

There will be no registration fee, thanks to the generous support of CEA and IHP.

We kindly ask that you inform the organizers of your intention to participate in the workshop by clicking the “Register Now” button to complete the registration form.

Test cases

Time-Dependent Recombination from a Bare Nucleus - This case revisits a classic problem first introduced at NLTE-1—time-dependent recombination of carbon from a bare nucleus—offering a unique opportunity to reflect on the progress made over the past 29 years. Today, this process has gained renewed relevance in the EUV and beyond-EUV lithography communities, where it is studied as a mechanism for generating narrow-band Ly-α emission in sub-10 nm plasma sources. Rather than limiting the scope to simple hydrogen-like ions, this test case invites participants to explore recombination in more complex ions such as He-like and Li-like systems. In these cases, three-body recombination can populate doubly excited states, with subsequent autoionization significantly influencing the overall recombination rate. While the lithography community typically focuses on elements with Z ≤ 13, the choice of element for this test case remains flexible, allowing contributors to explore the most scientifically compelling scenarios.

See Call for Submission for detail information

Location

Institut Henri Poincaré (IHP) is a research institute of Centre national de la recherche scientifique (CNRS), devoted to mathematics and theoretical physics. It is located on a small campus, called "campus Curie", which is full of science history. In this group of building was notably the former laboratory of Marie Slodowska-Curie, which may be visited as a museum today.

IHP website: https://www.ihp.fr/en

Institut Henri Poincaré

Room 201 (Maryam Mirzakhani)

11 Rue Pierre et Marie Curie, 75005 Paris, France

Computer Equipment

We will have an Internet connection at the meeting room and (probably) a dedicated wireless network for the Workshop purposes.

accommodation

There are numerous lodging options of different categories in the area near the Institute

Several mid-range and 4-star hotels are located near the campus. For reference, 3-star hotels typically cost around €200 per night.
For more affordable options, look around Cardinal Lemoine Station and nearby streets such as Rue Monge, Rue des Écoles, Rue Lacépède
As of June 2025, affordable hotels and apartments are available for approximately €150 per night or less.

Transportation

Paris airports - IHP

From Charles de Gaulle (CDG), Take RER line B directly to Luxembourg station (approx. 50 minutes).
From Orly (ORY), two options:
• Orlyval shuttle to Antony, then RER line B to Luxembourg (approx. 40 minutes)
• Metro line 14 to Maison Blanche, then line 7 to Place Monge (approx. 45 minutes)

Transportation in Paris

Paris now uses a unified fare system across its metro, RER, tram, and bus networks.
Trips to all airports have a distinct, but also unified fee.
Paper tickets are being phased out, so you'll need a rechargeable RFID card (available at metro stations) or you can use your smartphone.
Beware of pickpockets, especially when using your smartphone in the metro.

Useful links:

RATP (bus, metro and RER): https://www.ratp.fr/en
Paris airports company: https://www.parisaeroport.fr/en

Organizing Committee

Yuri Ralchenko (UMD/NASA, USA)

Robin Piron (CEA, France)

Franck Gilleron (CEA, France)

Stephanie Hansen (SNL, USA)

Christopher Fontes (LANL, USA)

Dipti (Clemson Univ., USA)

Min Sang Cho (LLNL, USA)

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