List of Ghost Beam Measurements

Below is a list of ghost beam measurements from its discovery on 8/16/18 to present.

August 2018

• 8/16/18 11pm Mamun ended a 1mA electron beam that ran for 9 hours. Gun HV: 200kV, Gun Solenoid at 200A, Anode bias at 1kV. [1]
• 8/16/18 11pm After discontinuing the laser, the ghost beam was visible on all three viewers and had a very high intensity. Mamun lowered the gun solenoid current to zero and then returned it to its original current but the ghost beam disappeared [2].
• 8/17/18 10:45am A brief rise in vacuum pressure near the gun was observed [3]
• 8/17/18 1pm With the gun HV at 200kV, gun solenoid at 200A, and anode bias at 1kV, all three viewers were inserted, but there was no ghost beam.[4]
• 8/19/18 7:38pm After running a 30uA beam for 10min with gun HV at 200kV and gun solenoid at 200A, a high intensity, stable ghost beam was observed and steered on all three viewers with no noticeable drop in intensity. [5] and [6]
• 8/19/18 11:59pm Continuing the ghost beam measurements, Mamun lowered the gun HV in in incremental steps of 10kV, returning to 200kV each time. The ghost beam intensity lowered with lower gun HV, but returned to the original intensity when brought back to 200kV [7]
• 8/20/18 12:42am Mamun lowered the gun solenoid current sequentially and brought it back to 200A. After each increment, the ghost beam was observed to go through spiral motion and move further and further to the edge of the viewer. Each time the gun solenoid current was brought back to 200A, the ghost beam returned to its original position, shape, and intensity. When the gun solenoid current was lowered to 40uA, the ghost beam disappeared and did not reappear when the current was brought back to 200A. [8]