Do we get new segment file everytime when refreshing?

Elastic Stack Elasticsearch
1

If the index refresh interval is 30s. Do I get new segment file every 30s even index buffer is not full?

Or refreshing is only force search reopen?

2

This should help clarify things - https://www.elastic.co/guide/en/elasticsearch/guide/2.x/near-real-time.html#near-real-time