A Lucene.Net developer works with the Lucene.Net library, a .NET port of the Lucene search engine library. Their role includes creating robust, high-performance indexing and search functionality for .NET applications. They utilize Lucene.Net to handle full-text indexing of documents for quick, accurate retrieval. Their tasks might involve tuning search algorithms, managing data indexing, developing complex search queries, and integrating Lucene.Net into various .NET applications. They also ensure data consistency, handle exceptions, and work on optimizing search performance. Their work contributes to enhancing the user's search experience in an application.