The Academy of Sciences of the Czech rebublic - ASCR


COMPASS-U will be a high magnetic field device with relevant plasma geometries is missing in the European fusion programme (and worldwide after the shut-down of Alcator C-MOD). The purpose of the project is to enlarge the COMPASS operational space, improve its performance and address some of the key gaps in the Plasma Exhaust Physics (PEX). The upgrade will keep the advantage of mid-size devices with their flexibility for scalings towards ITER and DEMO. The start of operation is planned at the end of 2021. A broad participation of the European and international partners in exploitation is expected.


The COMPASS-U design offers a wide, and in many ways unique, parameter range and a high flexibility of operation:

  • ITER and DEMO relevant geometry
  • High magnetic field (5 T), high density operation (~ 1020 m-3)
  • Advanced plasma configurations (double null, snow-flake)
  • Closed and well diagnosed high density divertor
  • Hot-wall operation (~ 300°C)
  • High PB/R ratio (PB/qAR ratio)
  • High power fluxes in the divertor (λq ~ 1 mm)
  • Possibility to study physics of advanced modes (QH-mode, I-mode, EDA-mode, etc.)
High capability to address the key Plasma Exhaust Physics challenges
Basic dimensions and parameters:
  • R = 0.84 m
  • a = 0.28 m
  • BT = 5 T 
  • Ip = 2 MA
  • PNBI = 4-5 MW 
  • PECRH = 4 MW (170 GHZ)
  • Triangularity  up to 0.6
  • Plasma volume ~ 2 m3
  • Discharge length 1-5 s
  • <Te> ~ <Ti> ~ 2.5 keV at high density
  • nG ~ 8 x 1020 m-3
  • Metallic first wall device
  • High-temperature operation (~ 300°C)


    Strategie AV21 Cryostat and the support structure assembly

    Strategie AV21 View inside COMPASS-U















    Strategie AV21 PF coil system

    Strategie AV21 Conventinal single-null divertor

    Strategie AV21 Snow-flake divertor