He received a per diem allowance to cover his travel expenses.

他收到一笔按日计算的差旅费用补贴。

《柯林斯英汉双解大词典》

During authorized business travel and work assignments, the company provides the required transportation and services and pays a per diem allowance to cover reasonable living expenses.

在核准的商务出差和工作安排期间，该企业提供所需的运输和服务，并支付每日津贴以负担合理的生活开支。

youdao

It gets interesting because they are all paid as part-time workers, and oftne have to take time away from their legal practices to serve, and also get a per diem allowance while in session, so people complain when they have too many special sessions.

FORBES: Texas Folds On TSA Anti-Groping Bill