(covers information from several alternate timelines)
Ashmore was working aboard Voyager when the ship was still in drydock. He passed Captain Kathryn Janeway and Vice Admiral Patterson during their tour in a corridor. Later, he was working on the second level in engineering. (VOY: "Relativity")
Ashmore was a fan of macaroni and cheese and in 2371 he asked Neelix to make it for him. When the Talaxian tried to make the cheese he accidentally infected some of the ship's bio-neural gel packs with the bacteria he cultivated. When Tuvok trained four Maquis cadets with a run through the corridors, they passed Ashmore. (VOY: "Learning Curve")
In 2373, during a confrontation with the Nerada, B'Elanna Torres ordered Ashmore to open up the emergency vent in plasma conduit G6 to reduce the pressure building there, while she attempted to reroute the plasma flow. (VOY: "Favorite Son")
Ashmore visited the mess hall when a group of alien scientists, the Srivani, were on board the Voyager and conducted medical experiments on the crew. Seven of Nine, who was able to see the aliens through her modified ocular implant, witnessed Ashmore and other crewmembers in the mess hall being lab rats to the Srivani. Ashmore also passed Seven of Nine in a corridor while the former Borg drone witnessed the Srivani and was present in the mess hall when Neelix prepared scrambled eggs and broke down due to the experiments. (VOY: "Scientific Method")
Ashmore was stationed in main engineering and armed with a phaser rifle when a member of Species 8472 attacked the engineering crew. He was wounded during the attack and treated in sickbay. (VOY: "Prey")
Later that year, Ashmore was on duty in engineering and worked on a console when Seven of Nine hit the Entharan arms dealer Kovin. Ashmore turned around and assisted B'Elanna Torres holding Seven back from attacking the Entharan a second time. (VOY: "Retrospect")
Ashmore assisted Harry Kim in a corridor while held prisoner by the Hirogen. As Kim suggested, Ashmore deviated a Hirogen and went to engineering with his guard. This gave Kim some time to talk to The Doctor. (VOY: "The Killing Game")
He passed Seven of Nine in a corridor after Voyager received a message from Admiral Hayes. Later, he passed Seven of Nine and Captain Janeway again in a corridor when the two headed for the transporter room to get beamed aboard the USS Dauntless. (VOY: "Hope and Fear")
In 2375 he was working in engineering when the ship lost its power and was drifting in the Void. Later he worked on a console while B'Elanna Torres gave the Malon Emck a tour through engineering. (VOY: "Night")
Also in 2375, a biomimetic copy of Ashmore was working in engineering aboard the Silver Blood copy of the Voyager. This copy was later among the patients in sickbay treated by The Doctor. (VOY: "Course: Oblivion")
Ashmore was on duty in engineering and ordered by The Doctor to lower the containment field around the series 5 long-range tactical armor unit after it was transported into engineering. He was also in engineering when the armor unit was transported into sickbay and when the Garan trader Onquanii tried to trade with the crew. (VOY: "Warhead")
Ashmore was present on the bridge, standing in front of one of the aft consoles, when the nucleogenic lifeforms attacked the crew of Voyager and defended himself with a phaser. (VOY: "Equinox, Part II")
Ashmore was one of the Starfleet officers who accompanied Captain Janeway on her shore leave. He manned a station aboard the Delta Flyer when Janeway was informed by Commander Chakotay, that Seven of Nine and Tuvok were kidnapped by Penk. (VOY: "Tsunkatse")
Ashmore was noticeably traumatized by an alien beacon, which was causing the crew to have horrific flashbacks of a slaughter of Nakan colonists. He was sitting on a camp bed and told by Janeway to keep being strong. (VOY: "Memorial")
He manned the side engineering station on the bridge when Chakotay tried to talk to Captain Janeway about her strange behavior and when Janeway informed the bridge crew she was not feeling well and would be in her quarters. Later, when The Doctor ejected the warp core of Voyager, Ashmore manned an aft station on the bridge. (VOY: "Renaissance Man")
Ashmore was on duty on the bridge when Voyager used the ablative armor and transphasic torpedos to destroy two Borg cubes and discovered the Borg transwarp hub inside a nebula. He also worked on the aft bridge when Voyager returned to Earth in 2378. (VOY: "Endgame")
Ensign Ashmore was played by regular Star Trek background actor and stand-in David Keith Anderson. His voice in "The Killing Game" was provided by an unknown actor. Meanwhile in "Memorial" his speaking role was the only time he spoke and received a credit as "Crew Member".
The authors of the Star Trek Encyclopedia (4th ed., vol. 1, p. 47) and StarTrek.com believed there were two Ashmores assigned to the Voyager.   In the Star Trek Encyclopedia, one was identified as a female, played by Christine Delgado, and the other as a male, played by an unnamed actor.
He was first mentioned in "Learning Curve", and not seen until "Year of Hell".
- "Learning Curve" (Season One)
- "Persistence of Vision" (Season Two)
- "Favorite Son" (Season Three)
- "Before and After"
- "Scientific Method" (Season Four)
- "Year of Hell"
- "Waking Moments"
- "The Killing Game"
- "The Killing Game, Part II"
- "The Omega Directive"
- "Hope and Fear"
- "Night" (Season Five)
- "Once Upon a Time"
- "Nothing Human"
- "Thirty Days"
- "Course: Oblivion"
- "Survival Instinct" (Season Six)
- "Barge of the Dead"
- "Fair Haven"
- "Blink of an Eye"
- "Inside Man" (Season Seven)
- "Workforce, Part II"
- "Human Error"
- "Renaissance Man"