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Chronological Thread 
  • From: RMKI PFO szeminarium-koordinator <szeminarium AT>
  • To: rmkiusers AT, NTI körlevél <mindenki AT>, fizinfo AT
  • Subject: [Fizinfo] Szeminarium (RMKI PFFO) *** ***
  • Date: Mon, 10 May 2010 10:17:20 +0200
  • List-archive: <>
  • List-id: ELFT HÍRADÓ <>
  • Organization: MTA KFKI-RMKI


Az MTA KFKI RMKI Plazmafizikai Foosztaly szeretettel meghiv minden
kedves erdeklodot az alabbi eloadasra:

Pellet ablation dependence on magnetic field intensity

Eloado: Lovasz Bela
ELTE, negyedeves fizikus hallgato

Idopont: 2010. majus 11. (kedd) 14:00

Helyszin: KFKI Campus, III epulet, 1. emelet, 105 teazo
1121, Budapest, Konkoly Thege Miklos ut 29-33.
Az intezet megkozelitheto a 90-es autobusszal:

H.323 kapcsolat: 0036100309910 (előadás és fóliák)

Az eloadas kivonata:

Nowdays well established fuelling and ELM control method for fusion devices are pellet injections. Pellets are small frozen portions of mostly hydrogen isotopes. An important parameter for injection of pellets is the penetration depth. At the first experimental fusion reactor called ITER, ELM pacing pellets have to pierce far into the pedestal area, whereas fuelling pellets have to even penetrate to the pedestal top of the hot fusion plasma.

When a hydrogen isotope pellet is shot in into the plasma, ablation sets in immediately. That means that high energy particles, mostly electrons, from the plasma are clashing into the surface of the pellet and are detaching material from the surface. Little energy is needed for deuterium to sublimate so a neutral cloud is formed and evolves quikly around the pellet. This cloud dilats gaslike. An electron flux from the plasma is streaming into the cloud raising the total energy of the cloud. Through heat conduction energy is getting to the surface of the pellet, detaching further particles. This flux causes a charge difference between cloud and plasma and this leads to an electric shielding. The shielding limits the electron flux so lesser electrons and lesser energy gets into the cloud per area. Thus the cloud size will determine the whole electron and energy getting into the cloud. The size of the ionized cloud is determined by the magnetic field strength, because average pathlength of the particles becomes smaller if the magnetic field lines get denser. When the cloud energy got high enough, ionisation of the cloud sets in, and a channel flow of the ionized cloud begins along the magnetic field lines. The ablation process is treated by the Hybrid ablation code.[1]

Theory expects a smaller ionized cloud and a slower ablation of the pellet with increasing magnetic field strength because the energy flux is smaller and greater penetration depth for the pellet. However, experiments at ASDEX Upgrade showed that the penetration depth is inversely proportional to the magnetic field strength.[2] This presentation compares the devitions of the theory and the experiments in detail with the hybrid ablation code.


[1] K. Gal et al., Nuclear Fusion 48, 085005 (2008)
[2] E. Belonohy et al., Nuclear Fusion 48, 065009 (2008)

Szepesi Tamas

Tamas Szepesi, RMKI PFO seminar coordinator
KFKI - Research Institute for Particle and Nuclear Physics
EURATOM Association
Letters: P.O. Box 49, H-1525, Budapest-114, Hungary
Phone: (36 1) 3922222 / 1467
Fax: (36 1) 3922598, 3959151
szeminarium AT,

szepesi AT

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