By Katsuya Yonehara
I remember that first time I met Alvin in a workshop at ANL in 2003. Rolland Johnson and Moises Kuchnir introduced me to him in a lunch break. We discussed about an induced magnetic field from a field emission electron in a gas-filled RF cavity by writing Maxwell’s equation on a napkin. As many people feel for him, I was immediately captured his warm personality. In a way back to the conference room, Moises whispered me that Alvin is the person who leads the discovery of top quark! After that, I often visited his office and talked about a lot of physics. He was always smiling even I asked him a crazy idea.
One of the highlights in our collaboration is solving a RF power loading in a Hydrogen gas-filled RF cavity by a beam induced plasma. We carried out the gas-filled RF beam test at MTA. Alvin brought up a beautiful RF power loading formula which solves an LCR resonator with the beam induced plasma loading. The formula predicts the experimental result very well, especially for the initial stage of plasma loading. However, the measurement shows more power loading than the prediction at the equilibrium condition where the feeding RF power from the RF source and the plasma loading are matched. We had a meeting every day to figure out the missing component. When we had only one week left for the beam test, I called Alvin and suddenly came up the concept that we need to include a residual ion in the plasma loading! Alvin immediately modified his formula and proposed to store Deuterium instead of Hydrogen in the cavity to proof the new concept. His guess is correct. The observed plasma loading in two different gases behave as his modified formula. Two journals we published based on the experimental result are still my best journal.
I have moved to the other project since 2016 and worked on a completely different subject. However, I still feel Alvin every day. He encourages me when I meet an issue. Please look out for us in the future.