TY - JOUR

T1 - Kinetic instabilities in two-isotopic plasma in the gas-dynamic trap magnetic mirror

AU - Shmigelsky, Evgeniy A.

AU - Meyster, Andrey K.

AU - Chernoshtanov, Ivan S.

AU - Lizunov, Andrej A.

AU - Solomakhin, Alexander L.

AU - Yakovlev, Dmitry V.

N1 - Sections of the study concerning the probe data processing, determining DCLC instability properties and DCLC suppression conditions analysis were supported by Russian Science Foundation (Grant No. 19-72-20139).

PY - 2024/11/15

Y1 - 2024/11/15

N2 - A fusion neutron source (FNS) based on the gas-dynamic trap (GDT, Budker Institute, Novosibirsk) is considered for confinement of two-species plasma heated by neutral beam injection in a regime where the fast ion distribution function is far from Maxwellian. Kinetic instabilities are expected to develop in this regime, and in this paper we investigate the ion-cyclotron instability evolving in moderate densities of pure hydrogen and mixed deuterium-hydrogen target plasmas. The properties of the studied unstable mode, such as its azimuthal wavenumbers, propagation direction and its being affected by changes in the bulk plasma density and composition, allow us to identify it as the drift cyclotron loss cone (DCLC) instability. This mode scatters fast ions and thereby leads to drops in diamagnetic flux signals and increases longitudinal energy and particle losses, with the average energy of the lost ions estimated to be far above the temperature of warm Maxwellian ions. Our interpretation is that the unstable wave grows due to interaction with the fast ions located near the loss cone in the velocity space and scatters them. Applying the method of suppressing the DCLC instability by filling the loss cone with warm plasma, we have determined the values of plasma density and deuterium percentage that allow us to suppress the DCLC instability in the GDT. These findings justify using mixed bulk plasmas in fusion neutron source operation.

AB - A fusion neutron source (FNS) based on the gas-dynamic trap (GDT, Budker Institute, Novosibirsk) is considered for confinement of two-species plasma heated by neutral beam injection in a regime where the fast ion distribution function is far from Maxwellian. Kinetic instabilities are expected to develop in this regime, and in this paper we investigate the ion-cyclotron instability evolving in moderate densities of pure hydrogen and mixed deuterium-hydrogen target plasmas. The properties of the studied unstable mode, such as its azimuthal wavenumbers, propagation direction and its being affected by changes in the bulk plasma density and composition, allow us to identify it as the drift cyclotron loss cone (DCLC) instability. This mode scatters fast ions and thereby leads to drops in diamagnetic flux signals and increases longitudinal energy and particle losses, with the average energy of the lost ions estimated to be far above the temperature of warm Maxwellian ions. Our interpretation is that the unstable wave grows due to interaction with the fast ions located near the loss cone in the velocity space and scatters them. Applying the method of suppressing the DCLC instability by filling the loss cone with warm plasma, we have determined the values of plasma density and deuterium percentage that allow us to suppress the DCLC instability in the GDT. These findings justify using mixed bulk plasmas in fusion neutron source operation.

KW - fusion plasma

KW - plasma instabilities

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85209949458&origin=inward&txGid=a52b8dffdf51e736c0554d744d1a2a3e

UR - https://www.mendeley.com/catalogue/692db6c5-52d1-3674-a718-2ffd98cbb71b/

U2 - 10.1017/S0022377824001399

DO - 10.1017/S0022377824001399

M3 - Article

VL - 90

JO - Journal of Plasma Physics

JF - Journal of Plasma Physics

SN - 0022-3778

IS - 6

M1 - 905900605

ER -