The name of the class is confusing; it's plasma physics and I'm not sure what "electronics" means here.

This was definitely the hardest physics class I've taken so far, but it was worth it. The material is confusing and it takes you a while to understand, but Prof. Mori is very helpful and he's so enthusiastic that you feel motivated to put the effort in.

Expect yourself to spend several hours on the homework. His notes are very important, since they go much deeper than the book (Chen). I'd strongly suggest you take physics 105B (AM II), 110B (electromagnetism II), and 114 (waves, acoustics, and fluid dynamics) before taking this class. Make sure you're comfy with complex numbers and their application to solving differential equations by foruier analysis: Prof. Mori will cover it in lecture if you don't know it, it's a lot to take in.

Prof. Mori is sympathetic, and after some of us messed up the midterm, he assured us that he'd grade the finals separately and make sure that if someone does well on the final, their grade will not be pulled down by bad performance in the beginning of the quarter.

Take this class; it's worth the work.

M122 is a tough class. Usually plasma physics will be a graduate class, but in this senior-level version the topics are only slightly easier. Although the req for this course is only 110A, it actually relies heavily on electrodynamics and Maxwell's equations, so be prepared on EM or take 110B before this class.
Professor Mori is a big figure is plasma physics, and he has a unique teaching style. Although the textbook of this course (Chen) is a real classic, he lectured mainly on his own notes which, despite being very hard to read, expanded on certain topics (e.g. kinetic theory) and sometimes offered different perspectives on how to approach problems in plasma physics. His lectures were fast-paced and often assumed familiarity with a variety of topics (e.g. fluid mechanics), but he was patient to explain them if someone asked. It will be good if you read the lecture notes before attending the lectures so that you won't get lost in the lenthy derivations. In addition to the usual topics covered in the course, he also talked about many interesting applications and recent breakthroughs related to the physics in the lectures, which made the lectures a really rewarding experience.
Some of the homework problems came from the Chen textbook, while others are original problems which were notoriously hard. Both midterm and final were open book and somehow similar to the homework problems. There was also a Jupyter notebook assignment in which you run PIC simulations and analyze the results. The notebooks were really interesting and helped me understand the course materials.
Overall, the course is very difficult, but also very rewarding because you get the privilege to be familiar with plasma physics earlier than most undergrad physics students. I recommend the course and Professor Mori to anyone interested in plasma physics.