The ticker symbol for CBOE Volatility Index options is VIX. After entering the ticker select Options followed by the desired contract from the option chains window.
VIX index individual options trade from 09:30 EST to 16:15 EST, but also during extended hours (overnight) from 20:15 EST to 9:15 EST.
Clients may search the IBKR contract database through the Contract Search tool available from the Support area of the IBKR website.