By analyzing the marks Vs rank analysis of past 3 years and also by comparing the difficulty level of GATE 2018 with GATE 2016&2017, you can expect your rank somewhere between 700-900.

With this rank, you can apply for IIT Madras MS program in Interdisciplinary as well as for IISC Bangalore MSc program at Department of Instrumentation and applied physics. But yes one have to face a interview in order to get admission in above course.